Patent Publication Number: US-2017370678-A1

Title: Systems, Methods and Computer-Readable Media for Improving Platform Guidance or Navigation Using Uniquely Coded Signals

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation-In-Part of U.S. non-provisional patent application, assigned application Ser. No. 15/140,381, filed Apr. 27, 2016, entitled “Systems, Methods and Computer-Readable Media for Improving Platform Guidance or Navigation Using Uniquely Coded Signals, which application claimed the benefit of the filing date of a provisional patent application assigned application Ser. No. 62/156,880, filed on May 4, 2015, entitled “A Method for Improving Commanded Platform Guidance Using Coded Signals,” the entire contents of these applications are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The invention relates to systems and methods for determining the position and relative motion (if any) of a non-cooperative object and the position and relative motion of a cooperative platform while guiding or navigating the cooperative platform relative to the non-cooperative object. 
     BACKGROUND 
     Command guidance fire control systems are used to guide a missile into a target. Command guidance fire control systems track the position and motion of the missile and of the target while controlling the flight path of the missile to cause it to intercept the target. The missile is often referred to as an interceptor or interceptor platform. The target is a “non-cooperative object,” and will be referred to herein interchangeably as a target or as a non-cooperative object. The command guidance fire control system includes one or more radar systems located at a fire control sensor station of the command guidance fire control system. The fire control sensor station may be fixed (e.g., when located on or in a structure or structures) or unfixed (e.g., when located on or in a non-moving vehicle) or the fire control sensor station may be located on a moving platform, such as a ship, a tank, an airplane, etc. The command guidance fire control system also includes a receiver located on the interceptor platform and a transmitter located at the fire control sensor station. 
     The radar system transmits radar signals from the fire control sensor station. The radar system includes a radar sensor that detects radar signals reflected off of the non-cooperative object and off of the interceptor platform. A processor of the fire control sensor station processes the detected radar signals and determines the position and motion of the target and of the interceptor platform. The processor then computes a guidance solution. The transmitter located at the fire-control station transmits the guidance solution to the receiver located on the interceptor platform. The guidance solution is processed by a processor on the interceptor platform that causes the flight path of the interceptor platform to be adjusted, if necessary, to maintain a flight path that will intercept the target, or non-cooperative object. 
     One of the problems inherent in a conventional command guidance fire control system attempting to intercept a target is that the computation of the guidance solution at the fire-control sensor station and the communication of the guidance solution to the interceptor platform introduce excessive time delays between the time of determining target position and motion and the time of guidance solution command execution on the interceptor platform. These delays are attributed to: 1) the time that is required for the fire control sensor station to detect and determine the separate position and motion of both the target and the interceptor platform: 2) the time that is required for the fire control sensor station to compute the guidance solution in a coordinate frame convenient for the interceptor platform to execute guidance solution commands; 3) the time that is required for the guidance solution to be communicated from the fire control sensor station to the interceptor platform; and 4) the time that is required for the interceptor platform to process the received communication. 
     For the fire control sensor station to determine accurate guidance commands in a coordinate frame convenient or suitable for use by the interceptor platform, the fire control sensor station must have knowledge about the orientation of the interceptor platform, which requires time and resources that can degrade the efficiency of the fire-control sensor station. Also, the requirement for the fire control sensor station to track the interceptor platform can introduce errors in the position and motion of the interceptor platform due to a lack of a stable reflection from the interceptor platform. These errors, in turn, introduce two-way path signal propagation spreading losses that impose signal-to-noise requirements on the command guidance fire control system that may be difficult to meet. 
     To address the time delay problems associated with conventional command guidance fire control systems, methods have been used to enhance guidance solution processing at the fire control sensor station processor and to improve the communication links between the fire control sensor station and the interceptor platform. One conventional method for aligning the coordinate frame of the interceptor platform with the coordinate frame of the fire control station requires that the fire control sensor station track the motion of the interceptor platform through one or more maneuvers. These jink maneuvers include one or more changes of direction to allow the fire control sensor station&#39;s estimate of the interceptor platform velocity vector to be aligned with an onboard inertial sensor estimate of the interceptor platform velocity, but generally require either communicating the interceptor platform velocity from the interceptor platform to the fire control sensor or communicating the fire control sensor station&#39;s estimate of interceptor platform velocity to the interceptor platform and performing the alignment computation in the interceptor platform processor. In either case, the coordinate alignment adds complexity and processing requirements to the command guidance fire control system. 
     Other solutions for addressing these issues have introduced active and semi-active seekers onboard the interceptor platform to compute the position and motion of the non-cooperative object on the interceptor platform. While these systems mitigate timing delays and eliminate the need for jink maneuvers, they introduce another level of complexity that can impact overall system cost. In particular, these seeker solutions require alignment and calibration of the onboard sensor hardware with the on-board inertial navigation hardware that can add to complexity and cost. 
     In general, the existing solutions incur significant time delays due to increases in processing overhead and information sharing requirements between the fire control sensor station and the interceptor platform and/or increase onboard interceptor platform hardware complexity and cost. 
     U.S. Pat. No. 8,120,526 (hereinafter “the &#39;526 patent”), which is assigned to the applicant of the present application and which discloses inventions that were invented by the inventor of the present application, discloses a guidance system in which the interceptor platform is capable of self-determining its own position and motion and the position and motion of the target, or non-cooperative object, using coded signals. While the &#39;526 patent includes significant improvements over the above-described conventional systems, complexity and costs due to processing overhead requirements remain. 
     SUMMARY 
     Improved systems for locating, guiding or navigating platforms are disclosed. In some embodiments, a common coordinate system consisting of at least two orthogonal axes is used to avoid the above-described complexities in conventional guidance and fire control systems. Some applications define and apply a two-axis coordinate system to describe position, motion and orientation, while some other applications will call for a common or first coordinate system consisting of a three-axis coordinate system. Such a three-axis coordinate system will consist of three orthogonal (or substantially orthogonal) axes. 
     Embodiments of the improved systems include a spatially-distributed architecture (SDA) of antenna arrays that transmit a set of uniquely coded signals. Each antenna array in the SDA of antenna arrays has a known position in a first coordinate system. A first receiver having a known position in the first coordinate system defined by the SDA of antenna arrays receives reflections of the uniquely coded signals reflected by an object. One or more characteristics of the uniquely coded signals present in the reflected versions received by the first receiver are forwarded to a first processor. The first processor receives electrical signals representative of the reflected versions of the uniquely coded signals from the first receiver and identifies at least a position of the object in the first coordinate system. A platform, separate from both the SDA and first receiver, includes a second or platform receiver that receives non-reflected versions of the uniquely coded signals. A platform processor determines at least a position of the platform in the first coordinate system. 
     An alternative embodiment includes a first receiver having a known position in a first coordinate system, a first processor in communication with the first receiver, a platform separate from the first receiver. The first receiver receives reflections of a set of uniquely coded or uniquely identifiable signals transmitted from a spatially-distributed architecture (SDA) of antenna arrays having a known position in the first coordinate system. The platform is arranged with a second or platform receiver that directly receives the set of uniquely coded signals from the SDA of antenna arrays. The platform processor is in communication with the second or platform receiver and in response to information from the second or platform receiver determines a position of the platform in the first coordinate system. 
     Another example embodiment includes a method for locating at least one non-cooperative object and communicating the location of the at least one non-cooperative object, the method includes the steps of: receiving, with a receiver having a known position in a coordinate system, reflected versions of respective uniquely identifiable signals transmitted from a set of spatially-separated antenna arrays the respective positions of which are known in the coordinate system, where the reflected versions are reflected from a non-cooperative object; determining, with a processor in communication with the receiver, a location of the non-cooperative object, the determining based on one or more characteristics of the reflected versions of the uniquely identified signals; and communicating, from the processor in communication with the receiver, one of the characteristics of the reflected versions of the uniquely identified signals or the location of the of the non-cooperative object in the coordinate system. 
     Still another example embodiment includes a method for self-determining one or more of a position, a motion, and an orientation in a coordinate system and generating a guidance solution, the method including the steps of receiving, with a first receiver connected to a platform, a set of uniquely identifiable signals transmitted from respective spatially-distributed antenna arrays removed from the platform; determining, with a platform processor in communication with the first platform receiver, one or more of a position, a motion and an orientation of the platform, wherein the platform processor identifies at least one of the position, motion and orientation of the platform using one or more characteristics of the uniquely identified signals received by the first receiver; receiving, one or more signals containing information about a non-cooperative object; generating, with the platform processor, a guidance solution responsive to the relative position of the non-cooperative object with respect to the platform; and applying at least one control signal responsive to the guidance solution to direct the platform relative to the non-cooperative object. 
     In some embodiments, the example method described above may further include periodically receiving an informational signal identifying a present location of one or more of the antenna arrays or a position in a coordinate system relative to the location of the antenna arrays and adjusting a location of the platform responsive to the present location of the one or more of the antenna arrays and a platform determined position from one or more characteristics of the uniquely identified signals received by the first receiver. 
     In some other example embodiments, the example method may alternatively include generating a platform unique signal different from any member of the set of uniquely identifiable signals transmitted from the antenna arrays, transmitting the platform unique signal and periodically transmitting an informational signal identifying a present location of the platform. 
     Another example embodiment includes a receiver system at a known location in a coordinate system for guiding remote mobile platforms, the receiver system comprising an antenna, a transceiver coupled to the antenna and arranged to receive reflected versions of a set of uniquely identifiable signals transmitted from a respective set of spatially-distributed antenna arrays where the reflected versions are reflected by a non-cooperative object, a processor communicatively coupled to the transceiver and arranged to determine at least a position of the non-cooperative object in the coordinate system based on a respective time of arrival and phase of the reflected versions of the uniquely identified signals and an angular position and a range of the transceiver relative to an origin of the first coordinate system. 
     Another example embodiment includes a mobile platform that directly receives a set of uniquely identifiable signals transmitted from a respective set of spatially-distributed antenna arrays. A transceiver converts electromagnetic energy responsive to the set of uniquely identifiable signals to a first set of corresponding input signals. A processor uses a respective time of arrival and phase from the set of corresponding input signals to determine at least a position of the mobile platform in a first coordinate system defined by the set of spatially distributed antenna arrays. The mobile platform also receives information concerning a position of a non-cooperative object separate from the mobile platform. There are at least three separate and distinct mechanisms for the mobile platform to receive the information signal(s). 
     In a first mechanism, a receiver system coupled to the spatially-distributed antenna arrays receives reflected versions of the set of uniquely identifiable signals that are reflected from the non-cooperative object. A processor coupled to the receiver system determines a position of the non-cooperative object using the reflected versions and the arrangement of the spatially-distributed antenna arrays to identify the location of the non-cooperative object in a coordinate system defined by the spatially-distributed antenna arrays. The processor forwards one or more signals that identify the position, orientation and motion (if any) of the non-cooperative object via one or more information signals separate and distinct from the set of uniquely identifiable signals to the mobile platform. 
     In addition or alternatively, the mobile platform may be arranged with a sensor or sensor subsystem that provides one or more information signals to a mobile platform processor. The one or more information signals include a range and one or more angles with respect to the planes defined by the coordinate system defined by the spatially-distributed antenna arrays. Still further, the mobile platform may receive one or more information signals identifying the location of the non-cooperative object from one or more remote signal sources. When the remote signal sources forward information in a second coordinate system different from the coordinate system defined by the spatially-distributed antenna arrays, the mobile platform will perform a coordinate conversion before determining any necessary control signals to guide or navigate the mobile platform with respect to the non-cooperative object. Otherwise, when the remote signal source provides location information in the same coordinate system being used by the system directing the spatially-distributed antenna arrays a coordinate conversion may be avoided. 
     In some embodiments, the mobile platform is arranged with an inertial navigation system that provides a position, orientation and velocity of the platform to the platform processor. The mobile platform directly receives a set of uniquely identifiable signals transmitted from a respective set of spatially-distributed antenna arrays arranged on a pilot platform separate from the mobile platform. A transceiver on the mobile platform converts electromagnetic energy responsive to the set of uniquely identifiable signals to a first set of corresponding input signals. A platform processor uses a respective time of arrival and phase from the set of corresponding input signals and the spatial relationships between the antenna arrays to determine at least a position of the mobile platform in a first coordinate system defined by the set of spatially distributed antenna arrays. The processor uses the information from the inertial navigation system and one or more sensors or a sensor subsystem to generate a guidance solution to direct the mobile platform relative to the non-cooperative object. The mobile platform also receives a periodic information signal identifying a present position of each of the antenna arrays in the spatially-distributed architecture. The periodic information signal can be used by a platform processor to verify the accuracy of the position and orientation information in the inertial navigation system. When so desired, information in the periodic signal can be used to replace and/or adjust the position and orientation information in the inertial navigation system. 
     In these alternative embodiments, the mobile platform may be accompanied by or within communication range of one or more interceptor platforms. The interceptor platforms will be similarly arranged with one or more antennas, a transceiver and a platform processor suitable for receiving the set of uniquely coded signals from the spatially-distributed architecture of antenna arrays and determining a respective position, orientation and motion (if any) in the coordinate system defined by the physical arrangement of the spatially-distributed architecture of antenna arrays. The interceptor platforms may be further arranged with control and or guidance systems to direct or navigate the interceptor platform relative to the non-cooperative object. Each of the interceptor platforms may be arranged without a respective sensor or sensor subsystem that would enable each interceptor platform to autonomously determine the location of the non-cooperative object. When the mobile platform is within communication range of one or more interceptors, the mobile platform may communicate information about the non-cooperative target and the mobile platform&#39;s present position and orientation in the coordinate system defined by the spatially-distributed architecture of antenna arrays. The interceptor platforms may also receive the periodic information signal identifying a present position of each of the antenna arrays in the spatially-distributed architecture. The periodic information signal can be received directly from the system managing the spatially-distributed architecture of antenna arrays or indirectly via the mobile platform. However received, the periodic information signal is used by a respective interceptor platform processor to verify the accuracy of the position and orientation information in the inertial navigation system. When so desired, information in the periodic information signal can be used to replace and/or adjust the position and orientation information in the inertial navigation system. 
     Other alternative embodiments of a system of platforms are contemplated. A set of mobile platforms are arranged with a second antenna that is provided a platform unique signal. The platform unique signal is different from the members of the set of uniquely identifiable signals sent from the spatially-distributed architecture of antenna arrays. Each mobile platform directly receives a set of uniquely identifiable signals transmitted from a respective set of spatially-distributed antenna arrays arranged on a pilot platform separate from the mobile platform. A transceiver on the mobile platform converts electromagnetic energy responsive to the set of uniquely identifiable signals to a first set of corresponding input signals. A platform processor uses a respective time of arrival and phase from the set of corresponding input signals and the spatial relationships between the antenna arrays on the pilot platform to determine at least a position of the mobile platform in a first coordinate system defined by the set of spatially distributed antenna arrays. Each mobile platform is further arranged to transmit one or more informational signals. The informational signals may include information about the respective locations and orientations of the mobile platforms. The informational signals from each of the members of the mobile platforms coupled with the platform unique signals being transmitted from each of the members creates a secondary spatially-distributed architecture of antenna arrays that can be used by one or more interceptor platforms to determine their respective locations in the coordinate system defined by the secondary spatially-distributed architecture of antenna arrays. 
     Mobile platforms may be arranged to receive and process reflections of the uniquely identifiable signals sent from the (primary) spatially-distributed architecture of antenna arrays to determine one or more of a position, orientation and motion (if any) of a non-cooperative object responsible for the reflections. Alternatively, or in addition, interceptor platforms may be arranged to receive and process reflections of the platform unique signals sent from the secondary spatially-distributed architecture of antenna arrays to determine one or more of a position, orientation and motion (if any) of a non-cooperative object responsible for the reflections. Moreover, one or more mobile platform and/or one or more interceptor platform may be arranged with one or more sensors or sensor subsystems that identify a location of a non-cooperative object. Such mobile platforms and interceptor platforms may share information concerning the location, orientation and motion (if any) of the non-cooperative object in addition to information concerning their respective location in either the coordinate system defined by the primary spatially-distributed architecture of antenna arrays or the secondary spatially distributed architecture of antenna arrays as desired. 
     Another example embodiment includes a non-transitory computer-readable medium having code stored thereon for execution by a processor in a sensor system, the computer-readable medium comprising a transmit module arranged to communicate a set of uniquely identifiable signals to a SDA of N antenna arrays, where N is a positive integer greater than or equal to two, the SDA of N antenna arrays defining a first coordinate system; a receive module coupled to a first receiver located at a known position in the first coordinate system where the first receiver, receives reflected versions of the set of uniquely identifiable signals transmitted from the SDA of N antenna arrays and reflected by the non-cooperative object, determines a location of the non-cooperative object in the first coordinate system based on a respective time and phase of reflected versions of the uniquely identified signals and an angular position and a range of the first receiver relative to an origin of the first coordinate system, and forwards an information signal containing the location of the non-cooperative object in the first coordinate system. 
     Another embodiment includes a non-transitory computer-readable medium having executable code stored thereon for execution by a processor, the computer-readable medium comprising: a locator module integrated in a movable platform and arranged to receive a first set of signals responsive to non-reflected versions of a set of uniquely identifiable signals transmitted from a SDA of N antenna arrays, where the locator module determines one or more of a platform position, motion and orientation from spatial relationships of the N antenna arrays and a respective time of arrival and phase of the first set of signals in the first coordinate system; and a second module arranged to receive one or more of the position, motion and orientation of the platform from the locator module and the position and motion of the non-cooperative object from a signal source remote from the movable platform, where the second module generates one or more control signals to direct the movable platform with respect to the non-cooperative object. 
     A set of uniquely identifiable signals and or unique coded signals may include one or more mechanisms or signal processing techniques for generating and transmitting over the air radio-frequency electromagnetic signals that can be distinguished from each of the other members of a set of signals. Example mechanisms or signal processing techniques include time-division multiplexing, frequency-division multiplexing, code-division multiplexing, and polarization orientation coding. For some environments, a combination of one or more of these techniques can be used to generate a set of signals that do not interfere or minimally interfere with one another and are thus separately identifiable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Improved systems, methods and computer-readable media can be better understood with reference to the following drawings. Components and distances between components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles involved. 
         FIG. 1  is a functional block diagram of an example embodiment of an environment in which a sensor system uses coded signals to guide a platform or platforms relative to a non-cooperative object or target. 
         FIG. 2A  is a schematic diagram of an example embodiment of the spatially distributed architecture (SDA) introduced in the sensor system of  FIG. 1 . 
         FIG. 2B  is a schematic diagram illustrating an alternative embodiment of the SD architecture of  FIG. 1 . 
         FIG. 3A  is a schematic diagram of an example embodiment of the first receiver of  FIG. 1 . 
         FIG. 3B  is a schematic diagram of an alternative embodiment of the first receiver of  FIG. 1 . 
         FIG. 4A  is a schematic diagram of an example embodiment of a platform introduced in  FIG. 1 . 
         FIG. 4B  is a schematic diagram of an alternative embodiment of the platform of  FIG. 1 . 
         FIG. 5  is a schematic diagram that illustrates the manner in which the position and orientation of a target or non-cooperative object relative to the receiver of  FIG. 1  can be determined in two dimensions. 
         FIG. 6  is a schematic diagram that illustrates the manner in which the position and orientation of the second receiver relative to the SDA of  FIG. 1  can be determined in two dimensions. 
         FIG. 7  is a schematic diagram that illustrates the manner in which the position and orientation of the second receiver relative to the SDA of  FIG. 1  can be determined in three dimensions. 
         FIG. 8  is a schematic diagram that illustrates spatial relationships in an example arrangement of a SDA, receiver and a non-cooperating object of  FIG. 1  in two dimensions. 
         FIG. 9  is a schematic diagram that illustrates spatial relationships in an example arrangement of a SDA, a receiver with multiple antennas and a non-cooperative object of  FIG. 1  in two dimensions. 
         FIG. 10  is a flow diagram illustrating an example embodiment of a method for locating a non-cooperative object relative to a platform. 
         FIG. 11  is a flow diagram illustrating an example embodiment of a method for self-determining one or more of a position, motion and orientation in a coordinate system and guiding a platform relative to a remote non-cooperative object. 
         FIG. 12  includes a flow diagram illustrating an example embodiment of a method for self-determining one or more of a position, motion and orientation in a first coordinate system on a platform and using one or more signals containing information about a non-cooperative object to guide the platform relative to a non-cooperative object. 
         FIG. 13  is a flow diagram illustrating an alternative embodiment of the method introduced in  FIG. 12 . 
         FIG. 14  is a schematic diagram that illustrates an embodiment of a system of platforms including a group of mobile platforms navigating in accordance with location information from a SDA of antenna arrays. 
         FIG. 15  is a schematic diagram that illustrates another alternative embodiment of a system of platforms including a group of interceptor platforms navigating in accordance with a separate or secondary SDA of antenna arrays. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS 
     In accordance with illustrative or exemplary embodiments described herein, a spatially-distributed architecture (SDA) or signal subsystem transmits a set of N uniquely coded electromagnetic signals and receives information from reflected versions of the set of N uniquely-coded signals. The SDA or subsystem determines the position and motion (if any) of a non-cooperative object or target in a coordinate system defined by the SDA by comparing one or more characteristics of the reflected versions of the set of N uniquely-coded signals with the transmitted version of the transmitted signal with the same code. The set of N uniquely-coded signals are also received by a platform. The set of N uniquely-coded signals are received absent reflection from the non-cooperative object or target. The platform self-determines its position, motion, and orientation in the same coordinate system that the SDA or signal subsystem used to determine the position and motion of the non-cooperative object. Since the SDA determines the position and motion of the non-cooperative object and the platform separately self-determines a position, motion and orientation in a common coordinate system, jink maneuvers required by conventional systems for coordinate frame alignment are avoided. Consequently, the improved arrangement provides a savings in guidance system resources and reduces time delays in such navigation or guidance systems. In addition, because the SDA is tracking the target in the same coordinate frame that the platform is self-determining its own position and motion, no frame alignment is required, which also saves guidance system resources and reduces time delays. 
     As indicated, a set of uniquely identifiable signals and or unique coded signals may comprise a set of signals where each member signal is separately distinguishable from each of the remaining member signals. For example, separate electromagnetic radio-frequency ranges or channels from about 20 MHz to just under 100 GHz can be used to identify a set of separately distinguishable signals. This technique is commonly known as frequency-division multiplexing (FDM). FDM is an analog technology that divides a select frequency spectrum into logical channels. In the context of this application, each of the separate spatially-distributed antenna arrays is used to transmit a respective signal or channel. Due to the unpredictable Doppler shift of the signal spectrum in mobile environments, the channels are separated by guard bands that include a range of frequencies that lie between adjacent channels. None of the spatially-distributed antenna arrays is configured to purposely transmit signals in the guard bands. One or more radio-frequency filters may be deployed in support electronics to reduce interference in the channels and guard bands as may be desired. While the guard bands reduce the probability that adjacent channels will interfere they decrease the utilization of the frequency spectrum. 
     As is known, various ranges of radio frequencies or bands are better than others for specific radar applications. For example, for relatively lower frequency signals it is easier to generate relatively greater transmit signal power. In addition, relatively lower frequency signals require larger antennas to determine angles accurately and are less susceptible to signal attenuation due to environmental conditions. Conversely, for relatively higher frequency signals it is more difficult to generate significant transmit power and there is greater attenuation of transmit signal power. However, relatively higher frequency signals can take advantage of relatively smaller antennas and also provide relatively better accuracy and angular resolution of received reflections. Those skilled in the art of developing radar systems understand the trade-offs with the application of various frequency bands. 
     As is known, one or more oscillating signals having the same frequency can be shifted in degrees or time with respect to an unmodified member of the set of signals to generate respective phase differences between the oscillating signals. The phase difference between a reference or unmodified oscillator and time-shifted oscillators at the same frequency can be expressed in degrees from 0° to 360° or in radians from 0 to 2π. In the context of this application, one of the spatially-distributed antenna arrays is provided a signal from a reference oscillator and each of the remaining antenna arrays is provided a time/phase delayed version of the reference oscillator to generate a set of respective phase separated signals. 
     One method to generate phase separated signals is by using Linear Frequency Modulation (LFM) or Non-Linear Frequency Modulation (NLFM) to generate the unique signals. For LFM the frequency is increased (Up-chirp) or decreased (Down-chirp) in a linear fashion over the pulse thus creating a distinctive phase relationship. The Up-chirp signal can be separated from the Down-chirp signal by bandpass filtering the match filter outputs. The degree of separation is a function of the linear frequency slope and the time duration of the pulse commonly referred to as the time-bandwidth (TB) product. The higher the TB product the more separation is achieved. A similar separation can be achieved with NLFM signals using the TB product. 
     Costas codes are another example of using frequency changes to modulate the phase. In this case the pulse is divided into several smaller pulses and the frequency for each pulse is determined based on a schedule of frequencies that optimize signal separation performance. The finite nature of the Costas coding schemes requires large code length to achieve moderate signal separation. 
     Time-division multiplexing is another signal processing technique that can be applied to both digital and analog signals to logically separate transmitted signals from one another. A system architect defines a set of time slots that are respectively assigned to each of the spatially-distributed antenna arrays. In the context of this application, a specific spatially-distributed antenna array is assigned to transmit a corresponding signal within a designated time slot. Time-division multiplexing operates in a synchronized fashion at both the transmit node (i.e., an antenna array) and receiving nodes (a remote platform or other remote receiver). That is, when a first antenna array is transmitting a receiver functioning in synchronization with the transmitter “understands” that it is receiving information from the first antenna array and not from any of the remaining antenna arrays. Persons skilled in the art of radio-frequency communications are familiar with the use of oscillating circuits and control systems to generate both stable transmit frequencies and precisely timed clock signals. For example, a phase-locked loop circuit generates an output signal that is related to the phase of an input signal. Phase-locked loops can keep input and output frequencies the same over a range of operating conditions and can be used to synchronize signals identifying time slots in a time-division based signaling scheme. 
     As indicated, time differentiated communication systems must carefully synchronize the transmission times from each of the spatially distributed antenna arrays to ensure that they are received in the correct time slot and are distinguishable from each other. Since such synchronization cannot be perfectly controlled in a mobile environment, each time slot may be arranged with adjacent guard slots that reduce the probability that signals from respective antenna arrays will interfere, but at the expense of spectral efficiency. 
     Code-division multiplexing is another signal processing technique that can be applied to logically separate transmitted signals from one another. A communication system architect defines a set of unique orthogonal codes in a one to one relationship with each of the spatially-distributed antenna arrays. Each remote platform receiver or a remote receiver knows in advance which of the unique orthogonal codes has been assigned to a particular spatially-distributed antenna array. Since it is not possible to create unique sequences that are orthogonal for random starting points and which can make use of a code space, unique “pseudo-random” or “pseudo-noise” (PN) sequences are used in asynchronous code-division communication systems. PN sequences are binary signals that appear to be random but can be reproduced by intended receivers. 
     Gold codes are an example of a PN sequence suitable for use in mobile communication systems where a specific antenna array can be assigned a unique code or signature. A particular Gold code is used to modulate the transmit signal from a particular member of the antenna array. Such sequences have bounded and small cross-correlations across a set. Alternatively, Kasami codes (a particular type of Gold code) can replace the Gold codes or in particularly noisy channels Hadamard codes or Walsh-Hadamard codes can be deployed. Another known alternative includes the application of complex-valued sequences, which when applied to radio signals generates a signal having a constant amplitude, whereby cyclically shifted versions of the sequence result in zero correlation at a remote receiver. Such sequences are commonly known as Zadoff-Chu sequences. The cyclically shifted versions of these sequences are orthogonal to one another, provided that each cyclic shift, when viewed within the time domain of the signal, is greater than the combined propagation delay and multi-path delay-spread of that signal between the transmitter and receiver. 
     In addition to the aforementioned time, frequency and phase-differentiated communication signaling techniques for uniquely identifying a particular signal from a set of received signals, antenna polarizations can be manipulated or adjusted as well. An antenna polarization is defined by the orientation of the electric field or E-plane of the radio wave with respect to a common reference plane (e.g., the Earth&#39;s surface). An antenna&#39;s polarization is determined by its physical structure and orientation. In general, an antenna&#39;s polarization is elliptical. In some cases, the ellipse collapses and appears as a line (i.e., linear polarization). In linear polarization, the electric field of the radio wave oscillates in a single direction perpendicular to the direction of propagation of the radio wave. In other arrangements, the two axes of the ellipse are equal and produce a circular polarization. In circular polarization arrangements, both the electric field and the magnetic field rotate about an axis of propagation Polarized elliptical or circular radio waves are designated as right-handed for counter-clockwise rotation about the axis of propagation or left-handed for clockwise rotation about the axis of propagation. 
     For many radar applications the transmit antenna polarization is chosen to be either vertical (E-plane) or horizontal (H-plane). For a vertically polarized (Co-pol) antenna the separation of horizontally polarized (Cross-pol) signals is determined by the isolation of the antenna or the relative power difference between Co-pol signals and Cross-pol signals. Thus, when one antenna is transmitting and receiving vertically polarized signals and another is transmitting and receiving horizontally polarized signals the signal separation is determined by the degree of isolation provided by the receive antennas. Other combinations of antenna polarizations that can provide separation are left-hand circular and right-hand circular. 
     In an example embodiment, the platform uses one or more of a self-determined position, motion and orientation of the platform and one or more of a received position, motion and orientation of the non-cooperative object, as communicated by the SDA of antenna arrays, to guide or navigate the platform relative to the non-cooperative object. Such guidance of the platform relative to the non-cooperative object can adapt to present circumstances of the platform and the non-cooperative object in accordance with an operational mode of the platform. For example, in some embodiments the platform may operate in an intercept mode where a collision or near collision between the platform and a non-cooperative object are intended. Whereas, in other operational modes the platform is intended to avoid a non-cooperative object. When functioning in these alternative operational modes the platform may be programmed to orbit a non-cooperative object or maintain a desired range of separation distances and angles with respect to a non-cooperative object. 
     In an alternative embodiment a platform is arranged with a third receiver that receives reflections of the uniquely coded signals reflected by the non-cooperative object. In this example, the platform receives the reflected versions of the uniquely coded signals with the third receiver and generates a self-determined position (of the platform) and a platform determined position of the non-cooperative object to guide the platform with respect to the non-cooperative object in the coordinate system. 
     Example platforms that may use a self-determined position and a received position of a non-cooperative object in a common coordinate system include land-based vehicles and ships or other craft on the surface of a body of water. Other example platforms may include a portable device that is temporarily attached to an article of clothing worn by a person. These example platforms can use embodiments of the disclosed systems in two dimensions or three dimensions. Example non-cooperative objects that a platform may intercept or avoid include other land-based vehicles, ships or other watercraft, natural items and man-made structures. 
     Other example platforms that may use a self-determined position and a received position of a non-cooperative object in a common coordinate system include, for example, a missile, projectile, aircraft and spacecraft. These example platforms are more likely to use embodiments of the disclosed systems that operate in three dimensions. These non-terrestrial platforms may be guided with respect to non-cooperative objects that are both terrestrial and non-terrestrial. For example, non-cooperative objects in these embodiments may include land-based vehicles, ships or other watercraft, natural items, man-made structures, missiles, projectiles, aircraft and spacecraft. 
     An example embodiment of a navigation system can take advantage of the self-determined position, motion, and orientation of a platform in the coordinate system defined by the SDA of antenna arrays. For example, a navigation system can be arranged to assist ships as they navigate in or near a harbor. In such an embodiment, a SDA of antenna arrays transmits the uniquely coded signals directly to each ship arranged with a compatible receiver. A ship arranged with a compatible receiver (e.g., a platform) can self-determine a position or location in the coordinate system defined by the SDA of antenna arrays. The ship will also receive one or more signals describing the position and motion (if any) of one or more non-cooperative objects or features in the harbor in the same coordinate system. 
     In some alternative embodiments, the ship can transmit a signal including one or more identifiers and its self-determined position or location to other ships in the harbor. Or a transponder could be outfitted on each ship or buoy that would receive and retransmit the uniquely coded signals to a second receiver on the ship that would process the signals to determine the location of the ships or buoys in the SDA coordinate frame. In this case a common clock will be required for each ship or platform to determine the range or distance from the SDA to each ship-based receiver. The transponder can be configured to apply a fixed frequency shift to the received uniquely coded signals for enhanced detection in sea clutter and for identification of the transponder platform. 
     Also the ship may receive a list of known ship or buoy locations in the coordinate system defined by the SDA of antenna arrays from a receiver subsystem in communication with and at a known position relative to the origin defined by the SDA. The list may be provided in a configuration file and stored in a memory element accessible to a processor in communication with the compatible receiver. The list may be provided and stored well before the ship arrives at the entrance to the harbor. Otherwise, the list may be communicated in a signal dedicated for that purpose that is broadcast near the entrance of a harbor. In addition to the ship and buoy locations, the configuration file or local information may further include a set of way points defining a preferred channel or path for ships entering or exiting the harbor. The described navigation system may use a SDA of antenna arrays that define a two-axis coordinate system that compatible receivers can use to describe position, motion and orientation of ships and buoys in the harbor. 
     In this regard, the improved navigation or guidance systems may be arranged to communicate with cooperative objects in the environment that are outfitted with a suitable transponder. These cooperative transponders receive the N uniquely coded signals and modify the same before transmitting a modified version of the N uniquely coded signals toward a receiver subsystem or a platform or platforms in the environment. Such a device can be arranged to receive, modify, amplify and transmit modified versions of the N uniquely coded signals with a minimal delay. When modified by shifting the frequency by a unique value, the transponder may uniquely identify a cooperative platform such as a ship (which may or may not be moving) or a buoy that is fixed in a harbor. A transponder deployed on a ship could use a frequency shift or adjustment that is significantly greater than that which could be expected from any Doppler shift as a result of a moving surface ship. Furthermore, a suitably arranged transponder on a buoy would enhance the probability of a positive identification during adverse weather and/or high seas. 
     Similarly, an example embodiment of a navigation system can be arranged to assist planes as they navigate between hangars along a tarmac or even on taxiways and runways of an airport. In such an environment, a SDA of antenna arrays transmits the uniquely coded signals. A plane arranged with a compatible receiver (e.g., a movable platform) can self-determine a position or location in the coordinate system defined by the SDA of antenna arrays. In addition, the plane receives one or more signals indicative of the position and motion (if any) of non-cooperative objects, landmarks, or obstacles in the common coordinate system defined by the SDA of antenna arrays. 
     In an alternative embodiment, the aircraft can transmit a signal including one or more identifiers and its self-determined position or location to other aircraft at the airport and an optional ground controller. The aircraft may receive a data file or list describing runways, taxiways, outdoor temporary parking locations, hangars, etc. at a particular airport in the coordinate system defined by a local SDA of antenna arrays. The data file, database or list including local information may be provided and stored in a memory element accessible to a processor in communication with the compatible receiver. The airport specific local information may be provided and stored well before the aircraft arrives at the airport. Otherwise, the airport specific information may be communicated in a signal dedicated for that purpose that is broadcast as aircraft enter a controlled airspace near the airport. In addition, the above described data may further include a set of way points defining a preferred course or path for aircraft to use while taxiing from a runway to a particular hangar, gate, refueling station or other select destination at the airport. The described navigation system may use a SDA of antenna arrays that define a two-axis coordinate system that compatible receivers can use to describe position, motion and orientation of aircraft on the ground at the airport. 
     Another alternative embodiment of a navigation system can be arranged to direct public safety personnel in a building or other structure in the event of an emergency. In this embodiment, a SDA of antenna arrays transmits the uniquely coded signals. A fireman or police officer may be provided a portable device or receiver that can be clipped or otherwise secured to a belt or article of clothing worn by the individual. The portable receiver (e.g., a platform) can self-determine a position or location in the coordinate system defined by the SDA of antenna arrays. In addition, the portable receiver receives one or more signals indicative of the position and motion (if any) of non-cooperative objects, landmarks, or obstacles in the common coordinate system defined by the SDA of antenna arrays. 
     In an alternative embodiment, the portable receiver may be arranged with a speaker or other output device to provide audible tones or commands to assist the wearer of the portable receiver. In addition, an on-site controller may be provided to coordinate the actions of multiple safety personnel. 
     In an example embodiment, the portable receiver can transmit a signal including one or more device identifiers and its self-determined position or location to other personnel and an optional emergency coordinator or control entity. The portable receiver may be pre-loaded with a map or floorplan describing the layout of locations within the building. Such layout or local information may include the location of hallways, rooms, cubicles, mechanical rooms, elevators, stairways, etc. for a particular floor of the building in the coordinate system defined by the SDA of antenna arrays. In addition, the above described local information may further include a set of way points defining a preferred course or path to exit the building. The described navigation system may use a SDA of antenna arrays that define a two-axis coordinate system that compatible receivers can use to describe position, motion and orientation of the portable receiver in a coordinate system defined by the SDA of antenna arrays. 
     In still another example embodiment, additional platforms are arranged with respective second and third receivers. At least a first member of a group of platforms determines its respective distance from the non-cooperative object. At least two additional members of the group of platforms communicate a respective present position and a respective distance to the non-cooperative object in the coordinate system defined by the SDA. With this information, the first member of the group of platforms determines a position of the non-cooperative object in the coordinate system. The first member of the group of platforms communicates the position of the non-cooperative object to one or more of the remaining members of the group of platforms in the common coordinate frame defined by the SDA thereby allowing each platform to implement autonomous guidance relative to the non-cooperative object. 
     Alternatively, the first member of the group of platforms uses one or more of the position, motion and orientation of the first member of the group of platforms and one or more of the present position, motion and orientation of the non-cooperative object to generate a guidance solution to direct the first member of the group of platforms relative to the non-cooperative object. The first member of the group communicates its position, motion, and orientation to one or more of the remaining members of the group of platforms in the common coordinate frame defined by the SDA. Since the platforms self-determine their position, motion, and orientation in the common frame defined by the SDA, the remaining members of the group of platforms (i.e., those members other than the first member) may determine a respective separation distance and relative direction with respect to the first member of the group of platforms for the entire group of platforms to controllably navigate with respect to the non-cooperative object. 
     In another example embodiment, a platform includes a third receiver that receives a signal from a source other than the uniquely coded signals that are reflected from the non-cooperative object and other than a cooperative object that transmits a modified version of the N uniquely coded signals. In this example, the platform processor uses information from the signal received by the third receiver to determine a position of the non-cooperative object in a second coordinate system different from the coordinate system defined by the SDA of antenna arrays. However, the transformation from the second coordinate system to the common system defined by the SDA must be made known to the platform. 
     In still another example embodiment, additional platforms are arranged with respective second and third receivers as well as a transmitter and related circuitry for generating a new code that uniquely identifies a platform. The transmitter connected to or otherwise supported by the corresponding platform is used to generate and propagate a radio-frequency signal modulated with the respective new code, which is different from the codes transmitted from the SDA of antenna arrays defining the first coordinate system. In this embodiment, a platform or a group of proximally located platforms that are self-locating in the coordinate frame defined by the SDA of antenna arrays define or establish a new coordinate frame. The origin of the new coordinate frame can be established as the location of an identified platform or as a function of the locations of two or more platforms as determined with respect to the first coordinate system as defined by the SDA of antenna arrays. A swarm or set of proximally located platforms may be able to take advantage of the finer resolution that may be possible in the extended or new coordinate system. 
     In this alternative embodiment, at least a first member of a group of platforms determines its respective distance from the non-cooperative object. This determination can be made in the first coordinate frame based on reflected versions and directly received versions of the signals from the SDA of antenna arrays alone. The range to the non-cooperative object may be confirmed, replaced or adjusted based on round trip times of a uniquely coded signal transmitted from the platform, reflected by the non-cooperative object and received by the platform. One or more proximally located platforms may share self-determined location information derived in the first coordinate system and may add a confirmed, replaced, or adjusted range to the non-cooperative object based on respective round trip times of a respective uniquely coded signal transmitted from the respective platform. One or more of the proximally generated platforms may use the respective locations of the platforms and the respective ranges to the non-cooperative object to generated guidance and or navigation solutions with respect to the non-cooperative object. These guidance and or navigation solutions may be determined in the new coordinate frame and shared across the set of proximally located platforms. 
     In still another embodiment, a group of platforms can be configured to include a pilot platform, a targeting platform, and one or more interceptor platforms. The pilot platform is configured with spatially-distributed antenna arrays that are transmitting respective uniquely identifiable signals and a first or pilot receiver. The uniquely identifiable signals transmitted from each of the respective antenna arrays can be steered or directed as desired to increase the likelihood that the signals are reflected to the pilot platform receiver. As in other arrangements, the relative position of the pilot platform receiver with respect to an origin defined by the spatially-distributed antenna arrays is known. Additionally, as in the other arrangements the pilot platform is further configured with one or more signal generators and signal processors arranged to generate, distribute and control the transmission of the uniquely-identifiable signals and to receive and derive information about the locations, motion and orientation of the targeting platform and the one or more interceptor platforms from information derived from reflected versions of the uniquely identified signals. 
     Alternatively, the pilot platform may be arranged to transmit uniquely coded signals from the spatially-distributed antenna arrays. As described, differences in time of arrival and phase of the uniquely coded signals as received by a targeting platform can be used by a processor on the targeting platform to self-determine a relative location in a coordinate system defined by the arrangement of the spatially distributed antenna arrays. In addition to the uniquely coded signals, the pilot platform may be arranged to periodically transmit an information signal that identifies a present position of the pilot platform. 
     The pilot platform may be arranged with a cargo hold or other support to contain or carry the targeting platform and one or more interceptor platforms until the group of platforms is proximal to a defined location relative to a target or non-cooperative object. Upon arrival of the group of platforms at such a defined location, the targeting platform and one or more interceptor platforms may be energized and deployed. Alternatively, the group of platforms may be separately delivered or deployed by other vehicles or methods or may be configured to autonomously rendezvous at a designated location as may be desired. 
     The targeting platform is arranged with a receiver, an inertial navigation system and a sensor in addition to one or more control systems. The sensor may be an active sensor, a passive sensor, or may have operational modes where the sensor alternates between active and passive modes of operation. Radar or optical sensors are envisioned. Such sensors include associated electronics for amplifying and perhaps filtering incident light including infrared light received by one or more photosensitive diodes or in the case of radar for capturing electromagnetic energy from specific wavelengths and converting the same to electric signals before processing the same. One or more optical elements may be arranged to intercept, reflect and or collimate incident light. In some arrangements such sensors may rely entirely on reflected light from a remote source. Alternatively, such sensors or sensor systems may include support electronics and one or more light emitters and various optical elements for collimating and otherwise directing an active light source. Such sensors, however embodied, may be arranged with a field of view that is likely to encounter reflected energy from a non-cooperative object or target of interest. When a relatively narrow field of view is provided by such sensor systems, the optical elements and perhaps the photosensitive arrays of elements may be arranged in a gimbal with a corresponding control system arranged to track the reflected beam of electromagnetic energy. 
     Whether such optical sensors are passive or active, angular resolution of a beam vector together with information from the inertial navigation system can be used to determine a target location with respect to the targeting platform. The targeting platform can be arranged with one or more transceivers and antennas to communicate one or more informational signals including the location, orientation and motion (if any) of the targeting platform and/or a non-cooperative object or target. The one or more informational signals may be communicated to one or more interceptor platforms within range of the targeting platform. 
     In some arrangements, the targeting platform can be arranged with one or more propulsion systems to controllably navigate autonomously about a target. In addition, the targeting platform may use information from the sensor in addition to information from the inertial navigation system to navigate or guide the targeting platform relative to a desired position or location proximal to a target or to navigate or guide the targeting platform relative to the target or non-cooperative object without such an offset. Accordingly, the targeting platform may be programmed to orbit or traverse a desired pattern. 
     The one or more interceptor platforms are configured with a respective receiver, inertial navigation sensor, interceptor processor and one or more respective control systems. In some arrangements, a select one or more of the interceptor platforms can be arranged with one or more optional propulsion systems to controllably navigate the interceptor platform with respect to a target or other designated location as communicated from the pilot platform. However delivered or deployed, the one or more interceptor platforms are arranged to self-determine a respective position relative to the pilot platform. Each of the one or more interceptor platforms is arranged to use one or both of the self-determined position as determined by the uniquely identified signals and/or the interceptor specific inertial navigation sensor and a target location as communicated periodically from the pilot platform to determine a guidance solution that will intercept the target or non-cooperative object. 
     When the targeting platform and one or more interceptor platforms are deployed from a pilot platform, the respective inertial navigation system may be initially set or otherwise configured to identify a shared position or location with the pilot platform soon after the various platforms are energized. However, inertial navigation systems often introduce errors that may accumulate over time such that the estimated position of the targeting platform and one or more interceptor platforms may drift or stray from a desired position and orientation. In cases where the inertial navigation systems are not calibrated or adjusted with respect to the coordinate system defined by the spatially-distributed antenna arrays on the pilot platform, a set of corrective signals may be required to accurately coordinate the various platforms. To maintain accuracy, the targeting platform&#39;s self-determined position is periodically or intermittently aligned or adjusted with information determined on the pilot platform. 
     In this regard, the targeting platform determines its position and velocity in a second coordinate frame or coordinate system determined by the inertial navigation sensor and communicates both its velocity vector and time and phase measurements to the pilot platform. The pilot platform uses the time and phase measurements to estimate the targeting platform position and velocity in the first coordinate frame or coordinate system defined by the spatially-distributed antenna arrays and then determines a coordinate transform that aligns the targeting platform determined velocity vector with the pilot platform estimate of the targeting platform velocity vector to establish a frame alignment. The targeting platform also determines the location of a non-cooperative object in the second coordinate frame and communicates the location to the pilot platform. The pilot platform either directly or indirectly communicates the location of the non-cooperative object in the first coordinate frame to the interceptor platforms allowing these platforms to guide to the non-cooperative object location. 
     In another alternative embodiment, a set of one or more interceptor platforms is provided. A surface based group of spatially-distributed antenna arrays are arranged to transmit respective uniquely identifiable signals. A receiver system is co-located with the group of spatially-distributed antenna arrays or in a known location with respect to the spatially-distributed antenna arrays. The uniquely identifiable signals transmitted from each of the respective antenna arrays can be steered or directed as desired to increase the likelihood that the signals are reflected by the one or more interceptor platforms to the pilot platform receiver. As in other arrangements, the relative position of the pilot platform receiver with respect to an origin defined by the spatially-distributed antenna arrays is known. Additionally, as in the other arrangements the pilot platform is further configured with one or more signal generators and signal processors arranged to generate, distribute and control the transmission of the uniquely-identifiable signals and to receive and derive information about the locations, motion and orientation of the one or more interceptor platforms from information derived from reflected versions of the uniquely identified signals. 
     In this alternative embodiment, the one or more interceptor platforms are arranged with respective transceivers, platform processors, signal generators, and first and second platform antennas. In contrast with the previous embodiment that used a targeting platform with a sensor or sensor system to identify and locate a position of a target or non-cooperative object, the one or more interceptor platforms generate and transmit a second set of platform unique signals that are directed toward a target or non-cooperative object of interest. Reflected versions of the set of platform unique signals are received at the respective interceptor platforms and processed by the respective one or more interceptor processors. Accordingly, in such an arrangement each of the one or more interceptor platforms are arranged to self-determine a position in a coordinate system defined by the spatially-distributed antenna arrays, as well as determine an angular rotation and range which can be used to determine a position of a target or non-cooperative target with respect to interceptor platform. A respective processor can use this information to determine an appropriate guidance or navigation solution to apply to an interceptor platform based control system or to communicate a position of the target to a surface-based control entity operating the spatially-distributed antenna arrays. 
     In the figures, like reference numerals refer to like parts throughout the various views unless otherwise indicated. For reference numerals with letter character designations such as “ 102   a ” or “ 102   b ”, the letter character designations may differentiate two like parts or elements present in the same figure. Letter character designations for reference numerals may be omitted when it is intended that a reference numeral encompass all parts having the same reference numeral in all figures. 
     An environment  100  in which an example embodiment of an improved tracking and/or guidance system operates is illustrated in  FIG. 1 . The improved tracking and/or guidance system includes a spatially-distributed architecture (SDA) or signal generation sub-system  110  that is separated or remotely located from a non-cooperative object or target  120 . In the illustrated embodiment, the SDA  110  is arranged or located to the same side of each of the non-cooperative object or target  120 , a cooperative object  122 , a receiver subsystem or first receiver  130 , a platform  150 , as well as an alternative signal source  180 . The SDA  110 , receiver subsystem  130  and platform  150  are not so limited and in modified environments the SDA  110  will be spatially located in other relationships with respect to the receiver subsystem  130 , platform  150 , non-cooperative object or target  120 , cooperative object  122  and the alternative signal source  180 . 
     As indicated schematically in  FIG. 1 , the SDA  110  defines a first coordinate system  5 . The first coordinate system  5  includes an origin  10  where an X-axis  12 , a Y-axis  13 , and a Z-axis  14  meet. As further indicated schematically in  FIG. 1 , the X-axis  12  is orthogonal or approximately orthogonal to both of the Y-axis  13  and the Z-axis  14 . In addition, the Y-axis  13  is orthogonal or approximately orthogonal to the Z-axis  14 . The first coordinate system  5  provides a mechanism to spatially define the relative location and orientation of items in the environment  100 . While the origin  10  may be defined at any location within or about the SDA  110 , the origin  10  is preferably located at the phase center of the N antenna arrays forming the SDA  110 . 
     In the illustrated embodiment a three-dimensional coordinate space is shown. However, it should be understood that under some circumstances (e.g., operation of a motorized vehicle such as a radio-controlled car, a surface ship, a taxiing aircraft or a car over surfaces where there is little, if any change in one of the orthogonal dimensions) a two-dimensional coordinate space or X-Y plane is still useful for locating or defining a position of a portable device, the surface ship, taxiing aircraft, car or any other signal reflecting item on or near the X-Y plane. The location of non-signal reflective items may be communicated via local information describing an environment  100 . As is well known, a position or point on the X-Y plane is identified by two perpendicular lines that intersect each other at the point, which is defined by X-Y coordinates each separately defined by a signed distance from the origin to the respective perpendicular line. Alternatively, each point on a plane can be defined by a polar coordinate system where a point is defined by a distance from a reference point or origin and an angle from a reference direction. 
     In three dimensions, three perpendicular planes (e.g., a X-Y plane, a Y-Z plane, and a X-Z plane) that intersect each other at an origin are identified and three coordinates of a position or point in the three-dimensional coordinate space are defined by respective signed distances from the point to each of the planes (e.g., point x, y, z). The direction and order for the respective three coordinate axes define a right-hand or a left-hand coordinate system. The first coordinate system  5  is a right-hand coordinate system. Alternative coordinate systems can replace the first coordinate system  5 . Such alternatives include a cylindrical coordinate system or a spherical coordinate system. 
     Wherever located in the environment  100  with respect to the receiver subsystem  130 , the platform  150 , the non-cooperative object  120 , cooperative object  122  and the alternative or optional signal source  180 , the SDA  110  generates and controllably transmits N uniquely coded signals  113  where N is a positive integer greater than or equal to two. The SDA or signal generation subsystem  110  includes at least one signal generator  111  and N antenna arrays  112 . As indicated in  FIG. 1 , the N uniquely coded signals  113 , generated by and transmitted from the SDA  110 , impinge or directly encounter both the non-cooperative object  120  and the platform  150 . These non-reflected versions of the N uniquely coded signals  113  are reflected by one or more surfaces of the non-cooperative object or target  120  such that R reflections  114  of the N uniquely coded signals  113  are received by one or more antennas  132  at the first receiver or receiver subsystem  130 . 
     The improved systems and methods for guidance or navigation may be arranged to consider various objects as non-cooperative objects  120  in accordance with an environment of interest. For example, if the system is deployed in a harbor a group of non-cooperative objects  120  may include surface ships and other watercraft, buoys, flotsam, jetsam, etc. By way of further example, when the system is arranged to guide airborne platforms a group of non-cooperative objects  120  may include missiles, projectiles, aircraft, and even spacecraft. In still other examples, a non-cooperative object  120  may include stationary or non-stationary objects supported by land such as, cars, trucks, trains, tanks, fences, buildings, etc. It should be understood that when one or more cooperative objects  122   a - 122   n  are present in the environment  100  these cooperative objects  122   a - 122   n  may also reflect the N uniquely coded signals  113 . Cooperative objects  122  may include any stationary or non-stationary object whether on land, on the surface of a body of water, or airborne that communicates in some way to one of the receiver subsystem, the SDA or the one or more platforms  150 . 
     In the illustrated embodiment, the tracking and/or guidance system  100  includes a receiver subsystem  130  and a platform  150 . The SDA  110  may be a fixed station on the ground or a moving station disposed on a moving platform such as, for example, a ship, an airplane, a flying drone, a truck, a tank, or any other type of suitable vehicle (not shown). The SDA  110  includes an array of N antenna elements  112 , a signal generator (SG)  111  and other elements (not shown in  FIG. 1 ). The SDA  110  can be collocated with the receiver subsystem  130 , or as shown in the illustrated embodiment, is removed from but at a known position in the first coordinate system  5  relative to the origin  10 . Together, the SDA  110  and the receiver subsystem  130  determine a position of the target or non-cooperative object  120  in the coordinate system  5 . The receiver subsystem  130  is arranged with a radio-frequency communication link to send wireless information signals  140  to the SDA  110 . One or more clock signals, synchronization signals or codes may be communicated from the SDA  110  to the receiver subsystem  130  over the radio frequency communication link. Alternatively, the receiver subsystem  130  uses one or more wired connections to send information signals  139  to the SDA  110 . In an alternative arrangement, the above described clock signals, synchronization signals or codes are communicated via wired connections from the SDA  110  to the receiver subsystem  130 . However arranged, the information signals  139  or the wireless information signals  140  include information responsive to one or more characteristics of the R reflected versions  114  of the N uniquely coded transmit signals  113 , where R and N are positive integers and where R is less than or equal to N. 
     When so desired, the radio-frequency communication link may be arranged to send additional wireless information signals to one or more cooperative objects  122   a - 122   n.  These wireless information signals may include local information such as a floor plan, a harbor chart, an airport map, a city map, etc. In addition, the wireless information signals may include transponder configuration parameters. For example, a transponder configuration parameter may include a fixed frequency difference that a particular transponder is directed to apply to the N uniquely coded signals  113  received by the transponder. Each transponder in the environment  100  will be associated with one of the cooperative objects  122   a - 122   n.  Otherwise, the transponders associated with the respective cooperative objects  122  may include firmware or stored information that may include local information and a respective modification for the transponder to apply to the received N uniquely coded signals  113  before transmitting modified versions  117  of the N uniquely coded signals. In operation, modified versions  117  of the N uniquely coded signals  113  transmitted from the respective transponders in accordance with a designated modification can be used by one or more platforms  150  to identify the location and motion (if any) of the respective cooperative objects  122  in the coordinate system  5 . Example modifications to the uniquely coded signals  113  may include one or more of changes in frequency, time, phase or polarization. A separately identifiable change in any of these parameters or in combinations of these parameters can be used to uniquely identify cooperative objects  122   a - 122   n  in the environment  100 . 
     In the example embodiment, the receiver subsystem  130  is arranged with processing circuitry or a processor  131 , memory  135 , signal generator  138  and one or more antennas  132 . The memory  135  includes one or more logic modules and data values (not shown) that when controllably retrieved and executed by the processor  131  enable the processor  131 , in response to information derived from the R reflections  114  of the N uniquely coded signals  113  received at the antenna  132 , to determine a position of the non-cooperative object  120  in the first coordinate system  5 . Changes in the location of the non-cooperative object  120  relative to the SD architecture  110  and/or the receiver subsystem  130  may also be determined by the processor  131 . In turn, the processor  131  forwards the location and motion information associated with the non-cooperative object  120  to the signal generator  138  to format, amplify and or buffer the information for communication to the SD architecture  110  via one or both of the communication link  139  and the communication link  140 . 
     One or more of the N antenna arrays  112  or a separate dedicated antenna (not shown) is provided to wirelessly communicate information regarding the location and motion (if any) of the non-cooperative object or target  120  via communication link  115  to the platform  150 . The platform  150  uses the location and motion information received from the SDA  110  to track the location of the non-cooperative object  120 . In addition, the platform  150  uses both the location and motion information received from the SDA  110  and a self-determined location and motion as inputs to guide or navigate the platform  150  with respect to the non-cooperative object  120 . Thus, the platform  150  can be programmed or configured to operate in various modes of operation. For example, when the non-cooperative object  120  is in motion, the platform  150  can be configured to operate in a track mode where movements of the non-cooperative object  120  are recorded by the platform  150 . By way of further example, the platform  150  can be configured to track and maintain a specified separation distance from the non-cooperative object or target  120 . In another example, when the non-cooperative object  120  is stationary, the platform  150  can be configured to orbit or in some situations avoid the non-cooperative object  120 . When so desired, the platform  150  can be operated in an intercept mode that guides or directs one or more control systems of a projectile, missile, ship, airplane, drone, land-based vehicle, portable receiver etc., supporting the platform  150  to intercept the non-cooperative object or target  120 . An intercept condition occurs when the platform  150  moves within a desired distance of or contacts the non-cooperative object  120 . 
     The platform  150  uses the location and motion information received from the SDA  110  to track the location of the non-cooperative object  120 . Furthermore, the platform  150  uses both the location and motion information received from the SDA  110  and a self-determined location and motion as inputs to guide or navigate the platform  150  with respect to the non-cooperative object  120 . Moreover, the platform  150  uses modified versions  117  of the N uniquely coded signals  113  to also locate, identify and determine relative motion (if any) of one or more cooperative objects  122   a - 122   n  that might be located in the environment  100 . Thus, the platform  150  can be further programmed or configured to avoid and/or track both cooperative objects  122   a - 122   n  as well as non-cooperative object  120 . 
     In the example embodiment, the platform  150  is arranged with processing circuitry or a processor  151 , memory  155 , and one or more antennas  152 . Platform  150  may be fixed to one or more of a missile, a projectile, a ship, an airplane, a flying drone, a truck, a tank, or any other type of suitable vehicle or even a relatively small portable device (not shown). When the platform  150  is coupled to or part of a projectile, the platform  150  may be dropped, launched, expelled or otherwise separated from a ship, airplane, drone, or land-based vehicle. The one or more antennas  152  receive the N uniquely coded transmit signals  113  transmitted by the SDA  110 . The memory  155  includes one or more logic modules and data values (not shown) that when controllably retrieved and executed by the processor  151  enable the processor  151 , in response to information derived from the N uniquely coded signals  113  as received at the antennas  152 , to self-determine a position of the platform  150  in the coordinate system  5 . Changes in the location of the platform  150  relative to the SDA  110  may also be determined by the processor  151 . In addition, one or more of the antennas  152  or a dedicated antenna (not shown) may receive information identifying the location and motion (if any) of the non-cooperative object  120  as communicated by the SDA  110  via the communication link  115 . Thus, the one or more logic modules and stored data values can be transferred to the processor  151  to enable any one of the described or other operational modes. 
     As also illustrated in  FIG. 1 , an optional or alternative signal source  180  (or a set of such signal sources) may communicate an information signal  185  to the platform  150 . The information signal  185  may be received by one or more of the antennas  152  one or more of the optional antennas  154  and or a dedicated antenna (not shown). In an example embodiment, the information signal  185  includes location, motion (if any) and orientation of the non-cooperative object  120  in accordance with a coordinate system other than the coordinate system  5 . For example, the information signal  185  may include location as defined by latitude, longitude (in degrees, minutes, seconds format or in decimal format) and altitude in meters with respect to sea level as determined by a global positioning system (GPS) receiver or a signal source responsive to such a system. By way of further example, the platform  150  may be arranged with a GPS receiver (not shown) and the information signals  185  may each include a specific pseudorandom code known to the receiver, a time of transmission and the location of the satellite broadcasting the respective signal. In still other examples, the respective information signal may be sent from an airborne platform arranged with a synthetic aperture array that has identified a structure or other non-cooperative object  120 . However configured, when the location of the non-cooperative object  120  is provided to the platform  150  in a coordinate system other than the coordinate system  5  a conversion operation will be necessary for the platform  150  to determine its distance to the non-cooperative object or target  120 . 
     As also illustrated by way of dashed lines, the platform  150  may be accompanied by one or more instances of separate platforms  150   a - 150   n.  When so provided, each member of the group of platforms  150   a - 150   n  is arranged with one or more positioning antennas  152  and one or more tracking antennas  154 . As described, the positioning antennas  152  receive the N uniquely coded signals  113  transmitted from the SDA  110  and the tracking antennas  154  receive reflected versions  114  of the N uniquely coded signals that are reflected by the non-cooperative object  120 . When so arranged, at least one of the platforms  150  includes a respective platform processor (not shown) that determines a distance to the non-cooperative object  120 . The platform  150  receives information from at least two other members of the remaining platforms  150   a - 150   n.  The shared information includes the respective self-determined position, motion and orientation in the coordinate frame  5  and the determined position and motion (if any) of the non-cooperative object  120  in the coordinate frame  5 . The platform(s)  150  may be arranged with dedicated transceivers and signal processors (not shown) for communicating with the remaining platforms  150   a - 150   n.    
     In addition, the platform  150  communicates a self-determined position, motion and orientation and the calculated position of the non-cooperative object  120  in the coordinate frame  5  to other members of the group of platforms. Furthermore, the platform  150  may be arranged to generate a guidance or navigation solution to direct platform  150  with respect to the non-cooperative object  120 . Such guidance solutions may include instructions that direct control systems on the platform  150  to follow or intercept a moving non-cooperative object  120 , or to orbit or intercept a stationary non-cooperative object  120 . In some embodiments, such guidance or navigation solutions may generate control signals that direct the platform along an intended path, route or channel. In these embodiments, the guidance or navigation solutions may be arranged or programmed to avoid various objects in the environment  100 . In embodiments where multiple platforms  150   a - 150   n  are deployed each platform  150  will separately determine a guidance solution. Moreover, information may be shared with other members of the group of platforms  150   a - 150   n.  Such information may assist a platform  150  that is not receiving reflected versions  114  of the uniquely coded signals  113  to continue in a direction or path towards the non-cooperative object or target  120  until such time that whatever was blocking the path of the reflected signals is no longer in the way. 
     When so arranged, at least one of the platforms  150  includes a respective platform processor (not shown) that determines a distance to the non-cooperative object  120 . The platform  150  receives information from at least two other members of the remaining platforms  150   a - 150   n.  The shared information includes the respective self-determined position, motion and orientation in the coordinate frame  5  and the determined position and motion (if any) of the non-cooperative object  120  in the coordinate frame  5 . The platform(s)  150  may be arranged with dedicated transceivers and signal processors (not shown) for communicating with the remaining platforms  150   a - 150   n.    
     As further illustrated by way of dashed lines, the environment  100  may include one or more cooperative objects  122   a - 122   n.  When so provided, one or more platforms  150   a - 150   n  arranged with one or more positioning antennas  152  and one or more tracking antennas  154  will receive the N uniquely coded signals  113  transmitted from the SDA  110 , the reflected versions  114  of the N uniquely coded signals that are reflected from a non-cooperative object  120  and modified versions  117  of the N uniquely coded signals  113  that are received, modified and transmitted from the one or more cooperative objects  122   a - 122   n.  Both the positioning antennas  152  and the tracking antennas  154  may receive the N uniquely coded signals  113  transmitted from the SDA  110 , the reflected versions  114  of the N uniquely coded signals and the modified versions  117  of the N uniquely coded signals  113  transmitted from the one or more cooperative objects  122   a - 122   n.  It should be understood that for some arrangements of the platform positioning antennas  152  and platform tracking antennas  154  and respective signal processing circuits there may be situations where a frequency shift used by a transponder in a cooperative object  122  is large enough that the processing circuits coupled to the tracking antennas  154  may tune to a frequency band that is outside of the detectable range of the positioning antennas and the respective processing circuits. In these arrangements, the tracking antennas  154  and respective processing circuits will receive and process the modified versions  117  of the N uniquely coded signals  113 , while the positioning antennas  152  and respective processing circuits will receive and process the N uniquely coded signals  113  sent from the SDA  110 . 
       FIG. 2A  illustrates an example embodiment of the SDA  110  introduced in  FIG. 1 . In the illustrated embodiment, the SDA  110 ′ includes a SDA subsystem  201 , SDA circuitry  220  and N antenna arrays  228 . As indicated, the N antenna arrays  228  define the coordinate system  5  introduced in  FIG. 1 . The SDA subsystem  201  includes a processor  202 , input/output (I/O) interface  203 , clock generator  204  and memory  205  coupled to one another via a bus or local interface  206 . The bus or local interface  206  can be, for example but not limited to, one or more wired or wireless connections, as is known in the art. The bus or local interface  206  may have additional elements, which are omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers (e.g. circuit elements), to enable communications. In addition, the bus or local interface  206  may include address, control, power and/or data connections to enable appropriate communications among the aforementioned components. 
     The processor  202  executes software (i.e., programs or sets of executable instructions), particularly the instructions in the information signal generator  211 , TX module  213 , RX module  214 , and code store/signal generator  215  stored in the memory  205 . The processor  202  in accordance with one or more of the mentioned generators or modules may retrieve and buffer data from the local information store  212 . The processor  202  can be any custom made or commercially available processor, a central processing unit (CPU), an auxiliary processor among several processors associated with the SDA subsystem  201 , a semiconductor based microprocessor (in the form of a microchip or chip set), and application specific integrated circuit (ASIC) or generally any device for executing instructions. 
     The clock generator  204  provides one or more periodic signals to coordinate data transfers along bus or local interface  206 . The clock generator  204  also provides one or more periodic signals that are communicated via the I/O interface  203  over connection  216  to the TX circuitry  221 . In addition, the clock generator  204  also provides one or more periodic signals that are communicated via the I/O interface  203  over connection  217  to the RX circuitry  222 . The one or more periodic signals forwarded to the SDA circuitry  220  enable the SDA  110 ′ to coordinate the transmission of the N uniquely coded signals  113  to the N antenna arrays  228  via the connections  225  and the reception of informative signals from the receiver subsystem  130  via the N antenna arrays  228  or the optional connection  139 . The I/O interface  203  includes controllers, buffers (caches), drivers, repeaters, and receivers (e.g. circuit elements), to enable communications between the SDA subsystem  201  and the SDA circuitry  220 . 
     The memory  205  can include any one or combination of volatile memory elements (e.g., random-access memory (RAM), such as dynamic random-access memory (DRAM), static random-access memory (SRAM), synchronous dynamic random-access memory (SDRAM), etc.) and non-volatile memory elements (e.g., read-only memory (ROM)). Moreover, the memory  205  may incorporate electronic, magnetic, optical, and/or other types of storage media. Note that the memory  205  can have a distributed architecture, where various components are situated remote from one another, but can be accessed by the processor  202 . 
     The information signal generator  211  includes executable instructions and data that when buffered and executed by the processor  202  generate and forward a signal or signals that communicate at least P electrical measurements made by the first receiver in response to the reflections  114  of the N uniquely coded signals  113  transmitted by the N transmit arrays  228 , where P is a positive integer. Alternatively, the information signal generator  211  includes executable instructions and data that when buffered and executed by the processor  202  generate and forward a signal or signals that communicate a position and motion (if any) of the non-cooperative object  120  in the coordinate system  5 . 
     The code store/signal generator  215  includes executable instructions and data that when buffered and executed by the processor  202  generate and forward a set of N signals that are encoded or arranged in a manner that enable a receiver of the N signals, such as, the receiver subsystem  130 , the platform  150 , or both to separately identify each of the N signals at location separate from the SDA  110 ′. The TX module  213  includes executable instructions and data that when buffered and executed by the processor  202  enable the SDA subsystem  201  to communicate a set of uniquely identifiable signals to a spatially distributed architecture (SDA) of N antenna arrays  228 , where N is a positive integer greater than or equal to two, the arrangement of the N antenna arrays defining the coordinate system  5 . The TX module  213  includes executable instructions and data that when buffered and executed by the processor  202  enable the SDA subsystem  201  to receive reflected versions  114  of the set of uniquely identifiable signals  113  transmitted from the SDA of N antenna arrays  212  and reflected by the non-cooperative object  120  and determine a location of the non-cooperative object  120  in the first coordinate system  5  based on a respective time and phase of reflected versions of the uniquely identified signals and an angular position and a range of the receiver subsystem  130  relative to an origin of the first coordinate system  5 . 
     In the context of this document, a “computer-readable medium” can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-readable medium can be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic) having one or more wires, a portable computer diskette (magnetic), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory) (magnetic), an optical fiber (optical), and a portable compact disc read-only memory (CDROM) (optical). Note that the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance, optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory. 
       FIG. 2B  illustrates an alternative embodiment of the SDA circuitry  220 ′ introduced in  FIG. 2A . In the illustrated embodiment, the receiver subsystem  130  is in close proximity to the transmit circuitry  221 ′. The receiver subsystem  130  includes antenna  132  and receive circuitry  222 . The antenna  132  converts electromagnetic energy in the R reflections of the N unique coded signals  114  that arrive at the antenna  132  to electrical signals. The electrical signals are forwarded to the receive circuitry  222  where they are filtered and amplified. The transmit circuitry  221 ′ includes a master oscillator (MO)  223 , a synchronization clock (SYNC CLK)  224 , a set of transmit signal generators  226   a - 226   n  and a respective set of antennas  228   a - 228   n.  The master oscillator  223  generates a common carrier frequency that is distributed to each of the transmit signal generators  226   a - 226   n  and to the synchronization clock  224 . The synchronization clock  224  adjusts the common carrier frequency and forwards respective codes to each of the respective transmit signal generators  226   a - 226   n.  The synchronization clock  224  may divide the common carrier frequency by a factor before forwarding the codes. In turn, the transmit signal generators  226   a - 226   n  modulate the common carrier frequency with the respective codes and convert the common carrier frequency to a radio frequency. An output of each of the transmit signal generators  226   a - 226   n  is coupled to an input of a respective antenna  228   a - 228   n.  The antennas  228  receive the electrical signals produced by the transmit signal generators  226   a - 226   n  and convert the coded electrical signals to an over-the-air electromagnetic wave. 
     Although the illustrated embodiment shows the transmit signal generators  226   a - 226   n  and antennas  228   a - 228   n  in a one-to-one relationship, two or more of the transmit signal generators  226   a - 226   n  may share an antenna. Preferably, the transmit signal generators  226   a - 226   n  are augmented by a digital signal processor (not shown) that spatially directs the set of N uniquely coded transmit signals  113  in the environment  100 . Such directivity or beamforming techniques controllably direct the radio-frequency electromagnetic energy in a predictable way. Accordingly, a control system (not shown) or other source of information identifying a region of interest in the environment  100  may direct the SDA circuitry  220 ′ to send the set of N uniquely coded transmit signals  113  in the general direction of a target or non-cooperative object  120 . Similarly, the control system or other source of information identifying a region in the environment  100  where a platform  150  is expected to be located may direct the SDA circuitry  220 ′ to send the set of N uniquely coded transmit signals  113  in the general direction of the platform  150 . 
     The set of N uniquely coded signals  113  produced by the transmit signal generators  226   a - 226   n  are preferably orthogonal, or nearly orthogonal, to each other. This orthogonal coding enables the individual signals to be distinguished from one another at the receiver subsystem  130 . There are common signal coding and signal processing techniques that are suitable for this purpose, including, for example, time-division multiplexing, frequency-division multiplexing, code-division multiplexing, and polarization coding. For some environments a combination of one or more of these coding and signal processing techniques can be used to generate a set of signals that do not interfere with one another and are thus separately identifiable. 
     The antennas  228   a - 228   n  are spatially distributed in such a way that a small positional difference of the non-cooperative object or target  120  being tracked produces a relatively large differential path length between the R reflections of the N uniquely coded signals  114  that encounter the antenna  132 . The antennas  228   a - 228   n  may be arranged in formations that are planar or nonplanar. When supported by a structure or a vehicle the size of the formation will be limited only by the dimensions of the underlying structure or vehicle chosen to support the antennas  228   a - 228   n.  However supported, the antennas  228   a - 228   n  are spatially distributed in such a way that a small positional difference between an array of antennas  152  arranged on an platform  150  produces a relatively large differential path length between the N uniquely coded signals  113  that encounter the antennas  152 . 
       FIG. 3A  illustrates an example embodiment of the receiver subsystem  130  introduced in  FIG. 1 . In the illustrated embodiment, the receiver subsystem  330  includes a processor  331 , I/O interface  333 , clock generator  334  and memory  335  coupled to one another via a bus or local interface  332 . The bus or local interface  332  can be, for example but not limited to, one or more wired or wireless connections, as is known in the art. The bus or local interface  332  may have additional elements, which are omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers (e.g. circuit elements), to enable communications. In addition, the bus or local interface  332  may include address, control, power and/or data connections to enable appropriate communications among the aforementioned components. 
     The processor  331  executes software (i.e., programs or sets of executable instructions), particularly the instructions in the location module  336 , motion module  337  and information signal logic  338  stored in the memory  335 . The processor  331  in accordance with one or more of the mentioned modules or logic may retrieve and buffer data from the local information store  339 . The processor  331  can be any custom made or commercially available processor, a CPU, an auxiliary processor among several processors associated receiver subsystem  330 , a semiconductor based microprocessor (in the form of a microchip or chip set), an ASIC or generally any device for executing instructions. 
     The clock generator  334  provides one or more periodic signals to coordinate data transfers along bus or local interface  332 . The clock generator  334  also provides one or more periodic signals that are communicated via the I/O interface  333  over connection  342  to communicate wirelessly via antenna(s)  132  or connection  139  when the receiver subsystem  330  is proximal to the SDA  110 ′. In addition, the clock generator  334  also provides one or more periodic signals that enable the receiver subsystem  330  to coordinate the transmission of informative signals. The I/O interface  333  includes controllers, buffers (caches), drivers, repeaters, and receivers (e.g. circuit elements), to enable communications between the receiver subsystem  330  and the SDA subsystem  201 . 
     The memory  335  can include any one or combination of volatile memory elements (e.g., RAM, DRAM, SRAM, SDRAM, etc.) and non-volatile memory elements (e.g., ROM). Moreover, the memory  335  may incorporate electronic, magnetic, optical, and/or other types of storage media. Note that the memory  335  can have a distributed architecture, where various components are situated remote from one another, but can be accessed by the processor  331 . 
     The location module  336  includes executable instructions and data that when buffered and executed by the processor  331  generate and forward information to information signal logic  338  such as at least P electrical measurements made by the first receiver subsystem  330  in response to the reflections  114  of the N uniquely coded signals  113  transmitted by the N transmit arrays  228 , where P is a positive integer. Alternatively, the location module  336  may be arranged to forward a location in X, Y, Z coordinates relative to the origin  10  of the coordinate system  5 . 
     Motion module  337  includes executable instructions and data that when buffered and executed by the processor  331  determine and forward motion information to information signal logic  338  such motion information may include velocity vector values in X, Y, Z coordinates relative to the origin  10  of the coordinate system  5 . 
     Information signal logic  338  includes executable instructions and data that when buffered and executed by the processor  331  generate and forward a signal or signals that communicate a position and motion (if any) of the non-cooperative object  120  in the coordinate system  5 . In some embodiments, the information signal logic  338  may generate signals that provide local information to one or more cooperative objects  122   a - 122   n.  The information signal logic  338  may also generate signals that include one or more configuration parameters intended to be communicated to respective cooperative objects  122   a - 122   n.    
     As indicated, local information store  339  may include data describing a local map, chart, floorplan, etc. The local information store  339  may include locations of fixed items in the coordinate system  5  defined by the SDA  110 . The included data may also define one or more preferred paths, routes, or channels for the platform  150  to use. This included data may be communicated directly or indirectly from the receiver subsystem  330  to the platform(s)  150  as may be desired. In addition, the data in local information store  339  may receive updates or real-time information regarding the environment  100 . Such real-time updates may include the position of both fixed structures and moving platforms  150   a - 150   n  in the local environment  100 . In some arrangements, the local information store  339  may also receive information including the position and motion (if any) of one or more cooperative objects  122   a - 122   n  present in the environment  100 . 
       FIG. 3B  illustrates a functional block diagram of an embodiment of a receiver subsystem  330 ′. The receiver subsystem  330 ′ includes receiver circuitry  222  and one or more tracking antennas  132 . The receiver circuitry  222  is configured to operate in conjunction with the transmit circuitry  221 ,  221 ′ shown in  FIG. 1  and  FIG. 2B . In the illustrated arrangement, the receiver circuitry  222  includes a demodulator (DEMOD)  350 , matched filter bank  360  and a position calculating processor  331 ′. The demodulator  350  receives respective signals from the synchronization clock  224  ( FIG. 2B ) and the master oscillator  223  ( FIG. 2B ) as well as electrical signals from the tracking antennas  132  on connection  342 . The tracking antenna(s)  132  receives electromagnetic energy transmitted by the transmit circuitry  221  ( FIG. 2A ) and reflected off of the non-cooperative object or target  120  being tracked. The tracking antenna  132  may be a single antenna or an array of antennas. For ease of discussion, it will be assumed that the tracking antenna  132  is a single antenna. The demodulator  350  receives the carrier frequency from the master oscillator  223  and the synchronization clock  224  from the SDA circuitry  220 ′, which enable the demodulator  350  to demodulate and decode the R reflections of the N uniquely coded signals  114 . A matched filter bank  360  of the receiver circuitry  222  receives the demodulated signal from the demodulator  350  and filters the signal to separate the reflections of the N uniquely coded signals  114  from one another and determine the time, T, and phase, φ, of each respective signal. As further indicated in  FIG. 3B , separate time, T(r), and phase, φ(r) signals are forwarded to the position calculating processor  331 ′, which determines present X, Y, Z coordinate values in the coordinate system  5 . In this way, the position calculating processor  331 ′ determines a present position of the non-cooperative object  120 . In addition, the position calculating processor  331 ′ uses separate instances of present X, Y, Z coordinate values separated by a known time to determine a change in position of the non-cooperative object  120  over the known time. The position calculating processor  331 ′ divides the respective changes in position in each of the three coordinate directions to determine a velocity of the non-cooperating object  120  in each of the X, Y, and Z directions of the coordinate system  5 . In addition, the position calculating processor  331 ′ can apply similar logic to determine a present position and motion (if any) of a cooperative object  122 . 
       FIG. 4A  illustrates a functional block diagram of an embodiment of a platform  400 . In the illustrated embodiment, the platform  400  includes a processor  411 , I/O interface  413 , clock generator  414  and memory  415  coupled to one another via a bus or local interface  412 . The bus or local interface  412  can be, for example but not limited to, one or more wired or wireless connections, as is known in the art. The bus or local interface  412  may have additional elements, which are omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers (e.g. circuit elements), to enable communications. In addition, the bus or local interface  412  may include address, control, power and/or data connections to enable appropriate communications among the aforementioned components. 
     The processor  411  executes software (i.e., programs or sets of executable instructions), particularly the instructions in the location module  431 , motion module  432 , orientation module  433  and guidance module  434  stored in the memory  415 . The processor  411  can be any custom made or commercially available processor, a CPU, an auxiliary processor among several processors associated with the platform  400 , a semiconductor based microprocessor (in the form of a microchip or chip set), an ASIC or generally any device for executing instructions. 
     The clock generator  414  provides one or more periodic signals to coordinate data transfers along bus or local interface  412 . The clock generator  414  also provides one or more periodic signals that are communicated via the I/O interface  413  over connection  417  to communicate wirelessly via antenna(s)  152  or over connection  416  via optional antenna  154 . In addition, the clock generator  414  also provides one or more periodic signals that enable the platform  400  to coordinate the transmission of informative signals. The I/O interface  413  includes controllers, buffers (caches), drivers, repeaters, and receivers (e.g. circuit elements), to enable communications between the platform  150  and optional platforms  150   a - 150   n.    
     The memory  415  can include any one or combination of volatile memory elements (e.g., RAM, DRAM, SRAM, SDRAM, etc.) and non-volatile memory elements (e.g., ROM). Moreover, the memory  415  may incorporate electronic, magnetic, optical, and/or other types of storage media. Note that the memory  415  can have a distributed architecture, where various components are situated remote from one another, but can be accessed by the processor  411 . 
     The location module  431  includes executable instructions and data that when buffered and executed by the processor  411  generate and forward information to information signal generator  435  such as an platform location in X, Y, Z coordinates relative to the origin  10  of the coordinate system  5 . The motion module  432  includes executable instructions and data that when buffered and executed by the processor  411  determine and forward motion information to information signal generator  435 . Such motion information may include velocity vector values in X, Y, Z coordinates responsive to motion of the platform  400  relative to the origin  10  of the coordinate system  5 . The orientation module  433  includes executable instructions and data that when buffered and executed by the processor  411  determine and forward orientation information to information signal generator  435 . Such orientation information may include a roll angle and an orientation vector in X, Y, Z coordinates responsive to a present condition of the platform  400  relative to the origin  10  of the coordinate system  5 . When such orientation information is recorded and observed over time a roll rate over a select period of time may be determined. 
     Generally, a roll axis or longitudinal axis passes through a missile, projectile or aircraft from a respective nose to a respective tail. An angular displacement about this axis is called bank. A pilot of a winged aircraft changes the bank angle by increasing lift on one wing and decreasing it on the other. The ailerons are the primary control surfaces that effect bank. For fixed wing aircraft, the aircraft&#39;s rudder also has a secondary effect on bank. A missile will use other control surfaces to achieve a desired bank angle, while a projectile may be launched with an intentional roll rate that rotates or spins the projectile about its longitudinal axis. 
     The term pitch is used to describe motion of a ship, aircraft, or vehicle about a horizontal axis perpendicular to the direction of motion. A pitch axis passes through the aircraft from wingtip to wingtip. Pitch moves the aircraft&#39;s nose up or down relative to the pitch axis. An aircraft&#39;s elevator is the primary control surface that effects pitch. Yaw is a term used to describe a twisting or oscillation of a moving ship or aircraft around a vertical axis. A vertical yaw axis is defined to be perpendicular to the wings and to the normal line or path of flight with its origin at the center of gravity and directed towards the bottom of the aircraft. Relative movement about the yaw axis moves the nose of the aircraft from side to side. An aircraft&#39;s rudder is a control surface that primarily effects yaw. 
     A roll rate and an orientation of the platform  150  can be determined from a comparison of the polarization of signals transmitted from the antennas  228   a - 228   n  with respect to a gravity (or up-down vector) that may align with the Z direction of the coordinate system  5 . By aligning the polarization of the transmitted signals with the polarization of the antennas  152   a - 152   n  the orientation of the up-down vector can be tracked in time to provide the pitch, roll, and yaw orientation of the platform  150  as a function of time in the coordinate frame  5 . In addition, a similar alignment of the polarization of the transmitted signals with the polarization of the optional antenna(s)  154  the orientation of the up-down vector can be tracked in time to provide additional information concerning the pitch, roll and yaw orientation of the platform  150  as a function of time. For missiles and projectiles the antennas  152   a - 152   n  may be rearward facing whereas optional antenna(s)  154  may be forward facing. For these form factors, orientation information in the form of pitch and yaw information may be determined from signals received at both the antennas  152   a - 152   n  and the antenna(s)  154 , while roll orientation information may be determined solely from the antennas  152   a - 152   n.    
     Alternatively for these form factors, platform orientation including each of pitch, yaw and roll may be determined from the signals received by the antennas  152   a - 152   n  alone, from the signals received by the antenna(s)  154  alone, or platform orientation including pitch, yaw and roll maybe determined from signals received by the antennas  152   a - 152   n  and the antenna(s)  154 . 
     This orientation information is sent to the guidance/navigation module  434  which includes executable instructions and data that when buffered and executed by the processor  411  generate and forward information or control signals to one or more control systems (not shown) of the platform  400 . Such control systems may be arranged to navigate or otherwise direct operation of the platform  400  in accordance with information from various sensors in combination with information in local information store  438 . As described, the position and motion (if any) of the non-cooperative object  120  in the coordinate system  5  are communicated to the platform  400 . In environments that include cooperative objects  122   a - 122   n  with suitably arranged transponders, the platform  400  may also receive the position and motion (if any) of the cooperative objects  122   a - 122   n.  As described, cooperative objects  122   a - 122   n  may be uniquely identified using a transponder that is arranged or directed to apply a separately identifiable modification to the uniquely coded signals  113 . For example a time modification could change the time of retransmit to identify the cooperative object. To identify a select cooperative object  122 , the modified signal can be transmitted using a time code (staggered pulses that represent a unique time sequence). By way of further example, the phase structure can also be modified by multiplying a sequence of SDA waveforms by a sequence of phase rotations that uniquely identify the object. The position and motion of the cooperative objects  122   a - 122   n  may be communicated to the platform  400  via the receiver subsystem  130  and the SDA  110 . In addition, the position, motion and orientation of the platform  400  are self-determined in the coordinate system  5 . The position and motion (if any) of the platform  400  in conjunction with data in the local information store  438  (including location and motion (if any) of the non-cooperative object  120  and cooperative objects  122   a - 122   n ) are forwarded to the guidance/navigation module  434 . Thus, a coordinate conversion is not necessarily required on the platform  150 . One or more control signals generated by the guidance/navigation module  434  controllably direct the platform  400  with respect to the non-cooperative object  120  and the one or more cooperative objects  122  (when present) in light of the local information describing conditions in the environment  100 . 
     However, in some embodiments the platform  400  may be arranged to receive information concerning the non-cooperative object  120  from an alternate signal source that will typically be in a coordinate frame that is different from that defined by the coordinate system  5 . For example, the alternate signal source  180  may provide a location and motion (if any) of the non-cooperative object  120  in a GPS format. When this is the case, an optional conversion module  436  may be arranged with executable instructions and data that when buffered and executed by the processor  411  perform a coordinate conversion to translate a GPS data format to the coordinate system  5 . Alternatively, the conversion module  436  may be capable of translating information identifying the location, motion and orientation of the platform  400  in the coordinate system  5  to the GPS data format received from the alternate signal source  180 . Upon conversion, the converted information may be communicated to the guidance module  434  and or forwarded to one or more control systems provided on the platform  150 . 
     As further explained in association with an optional embodiment illustrated in  FIG. 1 , the platform  150  may be a member of a group of similarly configured platforms  150   a - 150   n.  When this is the case, the platform  400  may be arranged with an optional coordination module  437  that includes executable instructions and data that when buffered and executed by the processor  411  receives information from at least two other members of the remaining platforms  150   a - 150   n.  The shared information includes the respective self-determined position, motion and orientation in the coordinate frame  5  and the determined position and motion (if any) of the non-cooperative object  120  in the coordinate frame  5 . The coordination module  437  may further enable the platform  400  to communicate a self-determined position, motion and orientation and the calculated position of the non-cooperative object  120  in the coordinate frame  5  to other members of the group of platforms. Furthermore, the platform  400  may be arranged to generate a guidance solution for one or more of the other members of the group of platforms  150   a - 150   n.    
       FIG. 4B  illustrates a functional block diagram of an embodiment of a platform  400 ′. The platform  400 ′ includes platform circuitry  450 , one or more positioning antennas  152   a - 152   n  and one or more optional antennas  154 . The platform circuitry  450  is configured to operate in conjunction with signals from the transmit circuitry  221 ,  221 ′ shown in  FIG. 1  and  FIG. 2B . In the illustrated arrangement, the platform circuitry  450  includes a summing node  405 , receiver demodulator (RX/DEMOD)  410 , matched filter bank  420  and a position calculating processor  411 ′. The platform circuitry  450  further includes a phase-locked loop (PLL)  402 , local oscillator (LO)  404 , and a local clock  406 . The LO  404  provides a clock signal to the receiver demodulator  410  that is at the same frequency as the MO  223  of the SDA circuitry  220 , which enables the receiver demodulator  410  to locate the set of uniquely coded signals  113  transmitted from the SDA  110 . The local clock  406  is used by the receiver demodulator  410  to demodulate the set of uniquely coded signals  113 . The LO  404  and the local clock  406  preferably are synchronized to the MO  223  and the synchronization clock  224 , respectively, just before or shortly after launch of a missile, or deployment of the platform  150  by using the PLL  402  in the platform circuitry  450  to phase align the clock signal generated by LO  404  with the clock signal generated by MO  223 . The positioning antenna(s)  152   a - 152   n  receive electromagnetic energy directly transmitted by the transmit circuitry  221  ( FIG. 2A ). The positioning antenna  152  may be a single antenna or an array of antennas. However arranged, the summing node  405  receives the separate electrical signals provided by the positioning antenna  152  and forwards a composite signal to the receiver demodulator  410 . The receiver demodulator  410  receives the carrier frequency from the local oscillator  404  and the synchronization clock signal from the local clock  406 , which enable the receiver demodulator  410  to demodulate and decode the N uniquely coded signals  113 . A matched filter bank  420  receives the demodulated signals from the receiver demodulator  410  and filters the signals to separate the N uniquely coded signals  113  from one another and determines the time, T, and phase, φ, of each respective signal. As further indicated in  FIG. 4B , separate time, T(r), and phase, φ(r) signals are forwarded to the position calculating processor  411 ′, which determines present X, Y, Z coordinate values in the coordinate system  5 . In this way, the position calculating processor  411 ′ determines a present position of the platform  150 . In addition, the position calculating processor  411 ′ uses separate instances of present X, Y, Z coordinate values separated by a known time to determine a change in position of the platform  150  over the known time. The position calculating processor  411 ′ divides the respective changes in position in each of the three coordinate directions to determine a velocity of the platform  150  in each of the X, Y, and Z directions of the coordinate system  5 . 
     As indicated in the illustrated embodiment, the platform  400 ′ may be arranged with a receiver  460  for receiving over-the-air information signals. The over-the-air information signals may include information signal  115  generated and transmitted from the SDA  110  or information signal  185  generated and transmitted from an alternate signal source  180 , which may include information including a position of a non-cooperative object  120 . The electromagnetic waves in the over-the-air information signals are converted to electrical signals by the antenna  465 . The electrical signals may be filtered, demodulated and amplified to convey location and motion information responsive to the non-cooperative object  120 . Furthermore, the electrical signals converted by the antenna  465  may be buffered over time at the receiver  460  to determine changes in each of the X, Y, and Z coordinates over a specified time. When the over-the-air signals are generated and transmitted from the SDA  110 , the location and velocity of the non-cooperative object  120  are identified using X, Y, Z coordinates in the coordinate system  5 . When the over-the-air signals are transmitted from an alternative signal source  180 , the location and velocity of the non-cooperative object  120  may be provided in an alternate coordinate system different from the coordinate system  5 . For example, the location of the non-cooperative object  120  may be provided in GPS coordinates or other three-dimensional coordinate systems. When the location of the non-cooperative object  120  is provided in a coordinate system that is different from the coordinate system  5 , the platform processor  151  or some other processor will perform a coordinate transformation. Preferably, the platform processor  151  will convert or transform the location of the non-cooperative object  120  to the coordinate system  5 . 
     As further indicated in the illustrated embodiment, the platform  400 ′ may optionally be arranged with one or more tracking antennas  154 . When so provided, the one or more tracking antennas  154  receive M reflected versions  114  of the N uniquely coded signals  113 , where M is an integer less than or equal to N. For ease of discussion, the tracking antenna  154  is a single antenna. The electrical signal(s) received by the tracking antenna(s)  154  are forwarded to the receiver demodulator  410 . The receiver demodulator  410  demodulates the reflected versions of the N uniquely coded signals. The demodulated signals are forwarded to the matched filter bank  420 , which separates the reflected versions  114  of the N uniquely coded signals  113  from each other. The electrical signals representative of the over-the-air signals transmitted directly from the SDA  110  to the platform  150  traverse a first set of paths. Whereas, the electrical signals representative of the reflected versions of the over-the-air signals as received at the tracking antennas  154  have traversed from the SDA  110  to the non-cooperative object  120  and from there to the platform  150 . Consequently, the time and phase of each of these reflected signals will not be the same as the time and phase of the signals received at the positioning antennas  152 . When provided both sets of signals, the position calculating processor  411 ′ determines a platform position and a non-cooperative object position in the coordinate system  5 . In addition, when provided both sets of signals over time, the position calculating processor  411 ′ uses separate instances of present X, Y, Z coordinate values separated by a known time to determine a change in position of the platform  150  over the known time and to determine a change in position of the non-cooperative object  120  over the known time. The position calculating processor  411 ′ divides the respective changes in position of each of the platform  150  and the non-cooperative object  120  in each of the three coordinate directions to determine a respective velocity of the platform  150  and the non-cooperative object  120  in each of the X, Y, and Z directions of the coordinate system  5 . In addition, the position calculating processor  411 ′ can apply similar logic to determine a present position and motion (if any) of a cooperative object  122 . 
     For example, let s 1 (t−t 0 ) and s 2 (t−t 0 ) denote two signals transmitted from transmitters A and B respectively where t 0  is the time of transmit. Assume that signal s 1  is received at the first receiver at absolute time t 1  and the signal s 2  is received at the second receiver at absolute time t 2 . Assuming, a common frequency, an amplitude propagation model for these signals is defined by equation 1 and equation 2. 
         s   1 ( t−t   0 )= e   2πjf(t     1     −t     0     )  and  s   2 ( t−t   0 )= e   2πjf(t     2     −t     0     )    Equations 1 and 2
 
     The phase of the signals is defined by equations 3 and 4. 
       φ 1 =2πƒ( t   1   −t   0 ) and φ 2 =2πƒ( t   2   −t   0 )   Equations 3 and 4
 
     The differential time, t d , is related to the differential phase, φ d , as shown in equation 5. 
     
       
         
           
             
               
                 
                   
                     t 
                     d 
                   
                   = 
                   
                     
                       
                         t 
                         1 
                       
                       - 
                       
                         t 
                         2 
                       
                     
                     = 
                     
                       
                         
                           1 
                           
                             2 
                              
                             π 
                              
                             
                                 
                             
                              
                             f 
                           
                         
                          
                         
                           ( 
                           
                             
                               ϕ 
                               1 
                             
                             - 
                             
                               ϕ 
                               2 
                             
                           
                           ) 
                         
                       
                       = 
                       
                         
                           ϕ 
                           d 
                         
                         
                           2 
                            
                           π 
                            
                           
                               
                           
                            
                           f 
                         
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   5 
                 
               
             
           
         
       
     
     Thus, the time difference and phase difference are linearly related. Therefore, the terms time difference and phase difference refer to equivalent measured quantities up to a multiplier and resolving any ambiguities in phase. 
     A position calculating processor  131  of the receiver subsystem  130  performs a position-calculating algorithm, which calculates the X, Y and Z Cartesian (or polar) coordinates of the non-cooperative object  120  and the velocity of the non-cooperative object in the X, Y and Z Cartesian (or polar) directions in coordinate system  5  determined by the location of the antenna arrays  112  in the SDA architecture  110 . The manner in which these calculations are made is described below with reference to  FIGS. 5-9 . The position and velocity information output by the processor  131  is then sent to the SDA  110  via connection  139  or wireless communication link  140 . In turn, the SDA  110  transmits or communicates the position and motion of the non-cooperative object  120  to the platform  150  where a guidance solution is computed using the interceptor position and motion computed on the platform. 
     The use of multiple fixed polarized positioning antennas  152   a - 152   n  or a single rotating polarized positioning antenna  152  at the platform  150  enable the roll rate and orientation of the platform  150  with respect to a gravity vector to be determined. The polarization of the signals transmitted by the antennas  228   a - 228   n  can be arranged to align with a known up-down vector (gravity) at the location of the SDA  110 . By aligning the polarization of the transmitted signals with the polarization of the antennas  152   a - 152   n  the orientation of the up-down vector can be tracked in time to provide the pitch, roll, and yaw orientation of the platform  150  as a function of time in the coordinate frame  5  determined by the location of the antennas  228   a - 228   n  of the SDA  110 . This orientation information is sent to the guidance system (not shown) of the platform  150 . 
     Once the processor  151  of the platform  150  receives the coordinates of the position and velocity of the platform  150  and the coordinates of the position and velocity of the non-cooperative object  120 , a guidance solution is computed and the guidance system of the platform  150  makes any necessary correction to the flight path of the platform  150  to ensure that it is on course to intercept the non-cooperative object  120 . It should be noted that because the position and velocity of the platform  150  and of the non-cooperative object  120  are in the same coordinate frame, no frame alignment is needed, which provides the aforementioned advantages over the conventional command guidance fire control systems. 
     The processor  151  of the platform  150  could be responsible for computing the guidance solution or, alternatively, a separate processor on the platform  150  (not shown) could perform the task of computing the guidance solution. The platform  150  may be further arranged with a navigation control system or autopilot system (not shown) that includes a processor that converts the guidance solution into actual guidance commands or control signals that are then delivered to one or more servos or other control signal converters that adjust the position of one or more control surfaces (not shown) arranged on the platform  150 . Such control systems change the direction of the platform  150  based on the guidance commands or control signals. The processor  151  of the platform  150  may generate the guidance commands and deliver them to the guidance system, or a processor of the autopilot system may perform this function. As will be understood by persons of skill in the art, in view of the description provided herein, processing tasks may be performed by a single processor or distributed across multiple processors. 
     The receiver subsystem  130  and the platform  150  determine differential time and/or phase and absolute time-of-arrival measurements of the uniquely coded signals transmitted from the set of antennas  228   a - 228   n.  These time-based measurements and knowledge of the speed of the signal propagation enable calculations to be made of the differential and absolute path lengths over which the signals have traveled. These measured path lengths, in conjunction with knowledge of the distributed layout of the antennas  228  of the SDA  110  and the known spatial relationship between the receiver subsystem  130  and the SDA  110 , are used by the processor  131  and the processor  151  in the receiver subsystem  130  and the platform  150 , respectively. Based on this information, the receiver subsystem  130  determines the position and motion of the non-cooperative object  120  relative to the SDA  110  and the platform  150  self-determines its position and motion relative to the SDA  110 . 
     The determinations made by the receiver subsystem  130  are communicated to the SDA  110  and transmitted over-the-air to the platform  150 . These determinations are then combined with the determinations made by the processor  151  of the platform  150  to provide the platform  150  with the position and motion of the non-cooperative object  120  relative to the platform  150  to compute a guidance solution. 
     The times-of-arrival of the transmitted uniquely coded signals  113  at the receiver subsystem  130  and the platform  150  are measured and the differences between these times are calculated. The differential time calculations obtained by the receiver subsystem  130  and knowledge of the layout of the SDA  110  and its spatial relationship with the antenna(s)  132  of the receiver subsystem  130  are used by the processor  131  to determine the path lengths from the antennas  228   a - 228   n  to the non-cooperative object  120 . The differential time calculations obtained by the platform  150  and knowledge of the layout of the SDA  110  are used by the processor  151  to determine the path lengths from the antennas  228   a - 228   n  to the positioning antenna(s)  152  on the platform  150 . Because the clocks that are used by the transmit signal generators  226   a - 226   n,  the receiver subsystem  130  and the platform  150  are synchronized, as described above with reference to  FIG. 2B ,  FIG. 3B  and  FIG. 4B , the absolute arrival times of the signals can be determined by the receiver subsystem  130  and the platform  150 . The absolute arrival times can be used to determine the absolute ranges, and consequently, the full position vectors can be determined. These same principles can be applied to locate and determine relative motion (if any) of cooperative objects that receive, modify and transmit modified versions of the N uniquely coded signals. 
     The processor  131  and the processor  151  determine the path lengths by measuring the difference in time-of-arrival of the signals as described above or by measuring the differential phase φ of the signals. Use of relative phase measurements is called interferometry. Interferometry requires coherence in the transmit signal generators  226   a - 226   n.  While either technique can be used to calculate the angle-of-arrival, the relative accuracy of the measurements is not the same. Interferometry improves the accuracy of this process by comparing the relative phase shifts of the received signals to provide a very accurate angle measurement. 
     In example embodiments motion is determined using the determined range and the differential change in the range of the signal propagation paths. Once the differential change in each path length has been determined, the combination of these values allows the platform  150  to self-determine its motion and allows the receiver subsystem  130  to determine the motion of the non-cooperative object  120  by multiplying the unit position vector by the differential path length change. The algorithms that are executed by the processor  151  and the processor  131  to compute the positions and motions of the non-cooperative object  120  and of the platform  150 , respectively, include straight-forward trigonometric calculations as will now be described with reference to  FIGS. 5-9 . 
       FIG. 5  is a schematic diagram that illustrates the manner in which the position and orientation of a target or non-cooperative object  120  relative to the receiver platform  130  of  FIG. 1  can be determined in two dimensions using trigonometry. An example spatial relationship (not to scale) between a set of antennas, ANT 1  and ANT 2 , a receiver, RX 1 , and a reflective non-cooperative object or target  120  are shown in two dimensions in  FIG. 5 . An origin  10  is located equidistant between ANT 1  and ANT 2  when the distance a 1  between the origin  10  and ANT 1  is equal to the distance a 2  between the origin  10  and the ANT 2 . Stated another way, the origin  10  is the overall phase center of a spatially-distributed architecture of N antenna arrays comprising ANT 1  and ANT 2 . The range, |RSDC toTARGET | from center of the SDA (i.e., origin  10 ) to the target  120  and angular position, θ TARGET , of the object relative to the origin  10  can be determined by the receiver subsystem  130  based on the known spatial relationship between the origin  10  and the antenna  132  by using the measurements of the difference in time-of-arrival of the signals as described above or the differences in the phase φ of the signals. The range, |RSDC toRX1 | from origin  10  to the antenna  132  and the angular position, θ RX , of the antenna  132  relative to the origin  10  are known a priori. Consequently, the range, |RRX toTARGET |, from the antenna  132  to the target  120  and the angle, φ Object , of the target relative to the antenna  132  can be determined by the processor  131  of the receiver subsystem  130  using trigonometry, as will be understood by persons skilled in the art in view of the description provided herein. 
       FIG. 6  is a schematic diagram that illustrates the manner in which the position and orientation (not to scale) of the second receiver located on an platform  150  remote from the origin  10  defined by the SDA  110  of  FIG. 1  can be determined in two dimensions using trigonometry. In  FIG. 6 , a 1 , a 2 , RANT 1toRX2 , RANT 2toRX2 , and RSDC toRX2  are vectors. Given a known distance (|a 1 |, |−a 2 |) between the respective antennas ANT 1  and ANT 2  and the origin  10 , the differential distance (|RANT 1toRX2 |−|RANT 2toRX2 |) from ANT 1  and ANT 2  to RX 2  can be computed. RX 2  is the overall phase center of the positioning antenna(s)  152  located on the platform  150 . Using this information, the angle θ RX  can be determined, where θ RX  is the angle between the perpendicular to the line between the antennas ANT 1  and ANT 2  and the line to the antennas  152  from the origin  10 . This may be accomplished by measuring the difference in time-of-arrival of the signals from each antenna  228   a - 228   n  ( FIG. 2B ) and multiplying by the speed of the signal propagation or by relating the phase difference to time difference. In two dimensions, the differential range measurements and the angle θ RX  are related by the equation, 
       |RANT 1toRX2 |−|RANT 2toRX2 |=(| a   1   −a   2 |)sin θ RX ,   Equation 6
 
     If the receiver clock (e.g., clock  406 ) is synchronized with the transmitter clock (e.g., synchronization clock  224 ), it is possible to determine not only the relative difference in arrival time of the signals transmitted from ANT 1  and ANT 2  to RX 2 , but also the absolute arrival time of the transmitted signals at RX 2 . Using this information, it is then possible to determine the distance from RX 2  to each of the antennas ANT 1  and ANT 2 . Using standard trigonometric equations, the distance from RX 2  to the origin  10  can be determined. As will now be described, this two-dimensional system can be extended easily to three dimensions by adding one or more additional antennas and one or more respective unique codes. 
       FIG. 7  is a schematic diagram that illustrates the manner in which the position and orientation (not to scale) of the second receiver located on an platform  150  remote from the origin  10  defined by the SDA  110  of  FIG. 1  can be determined in three dimensions. The example embodiment shows relationships between three antennas, ANT 1 , ANT 2  and ANT 3 , and the positioning antennas  152  in the platform  150 , labeled RX 2 , in three dimensions. As indicated, there are two angles (θ RX , ψ RX ) that need to be computed to determine position. However, these angles can be determined from algebraic equations with well-established solutions. The solution to the resulting position equations follows, under the assumption of synchronized clocks and that the coordinate frame center (e.g., origin  10 ) is located at the centroid of the antenna location vectors a 1 , a 2 , a 3 , i.e., 
     
       
         
           
             
               
                 
                   
                     Tx 
                      
                     
                         
                     
                      
                     Center 
                   
                   = 
                   
                     
                       ( 
                       
                         
                           
                             0 
                           
                           
                             0 
                           
                           
                             0 
                           
                         
                       
                       ) 
                     
                     = 
                     
                       
                         
                           a 
                           1 
                         
                         + 
                         
                           a 
                           2 
                         
                         + 
                         
                           a 
                           3 
                         
                       
                       3 
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   7 
                 
               
             
           
         
       
     
     And it follows that 
     
       
         
           
             
               
                 
                    
                   
                     RSDC 
                     
                       toRX 
                        
                       
                           
                       
                        
                       2 
                     
                   
                    
                 
                 2 
               
               = 
               
                 
                   
                     
                       
                          
                         
                           RANT 
                           
                             1 
                              
                             
                                 
                             
                              
                             toRX 
                              
                             
                                 
                             
                              
                             2 
                           
                         
                          
                       
                       2 
                     
                     + 
                     
                       
                          
                         
                           RANT 
                           
                             2 
                              
                             
                                 
                             
                              
                             toRX 
                              
                             
                                 
                             
                              
                             2 
                           
                         
                          
                       
                       2 
                     
                     + 
                     
                       
                          
                         
                           RANT 
                           
                             3 
                              
                             
                                 
                             
                              
                             toRX 
                              
                             
                                 
                             
                              
                             2 
                           
                         
                          
                       
                       2 
                     
                   
                   3 
                 
                 - 
                 
                   
                     
                       
                          
                         
                           a 
                           1 
                         
                          
                       
                       2 
                     
                     + 
                     
                       
                          
                         
                           a 
                           2 
                         
                          
                       
                       2 
                     
                     + 
                     
                       
                          
                         
                           a 
                           3 
                         
                          
                       
                       2 
                     
                   
                   3 
                 
               
             
             , 
           
         
       
     
     and assuming Tx Center=(0 0 0), 
     
       
         
           
             
               
                 RSDC 
                 
                   to 
                    
                   
                       
                   
                    
                   RX 
                    
                   
                       
                   
                    
                   2 
                 
               
               · 
               
                 a 
                 1 
               
             
             = 
             
               
                 
                   
                      
                     
                       RANT 
                       
                         1 
                          
                         
                             
                         
                          
                         toRX 
                          
                         
                             
                         
                          
                         2 
                       
                     
                      
                   
                   2 
                 
                 - 
                 
                   
                      
                     
                       RSDC 
                       
                         toRX 
                          
                         
                             
                         
                          
                         2 
                       
                     
                      
                   
                   2 
                 
                 - 
                 
                   
                      
                     
                       a 
                       1 
                     
                      
                   
                   2 
                 
               
               2 
             
           
         
       
       
         
           
             
               
                 RSDC 
                 
                   to 
                    
                   
                       
                   
                    
                   RX 
                    
                   
                       
                   
                    
                   2 
                 
               
               · 
               
                 a 
                 2 
               
             
             = 
             
               
                 
                   
                      
                     
                       RANT 
                       
                         2 
                          
                         
                             
                         
                          
                         toRX 
                          
                         
                             
                         
                          
                         2 
                       
                     
                      
                   
                   2 
                 
                 - 
                 
                   
                      
                     
                       RSDC 
                       
                         toRX 
                          
                         
                             
                         
                          
                         2 
                       
                     
                      
                   
                   2 
                 
                 - 
                 
                   
                      
                     
                       a 
                       2 
                     
                      
                   
                   2 
                 
               
               2 
             
           
         
       
       
         
           
             
               
                 RSDC 
                 
                   to 
                    
                   
                       
                   
                    
                   RX 
                    
                   
                       
                   
                    
                   2 
                 
               
               · 
               
                 a 
                 3 
               
             
             = 
             
               
                 
                   
                      
                     
                       RANT 
                       
                         3 
                          
                         
                             
                         
                          
                         toRX 
                          
                         
                             
                         
                          
                         2 
                       
                     
                      
                   
                   2 
                 
                 - 
                 
                   
                      
                     
                       RSDC 
                       
                         toRX 
                          
                         
                             
                         
                          
                         2 
                       
                     
                      
                   
                   2 
                 
                 - 
                 
                   
                      
                     
                       a 
                       3 
                     
                      
                   
                   2 
                 
               
               2 
             
           
         
       
     
     The term RSDC toRX2  represents the vector from the center of the array of N antennas or origin  10 , to the receiver center, RX 2 , or antenna  152  (when one antenna is used). The terms RANT 1toRX2 , RANT 2toRX2 , RANT 3toRX2  represent the vectors from the antennas ANT 1 , ANT 2  and ANT 3 , respectively, to RX 2 . The terms a 1 , a 2 , and a 3  represent the vectors from the origin  10  to each of the antennas ANT 1 , ANT 2  and ANTT 3 , respectively. The derivation of these equations will be understood by those skilled in the art in view of this description. 
       FIG. 8  is a diagram that illustrates the relationship, in two dimensions, between two antennas, ANT 1  and ANT 2 , one receiver platform antenna  132 , RX 1 , and a target or non-cooperative object  120  being tracked. It should be noted once again, that in three dimensions, there are more choices for how to arrange the antennas. In addition, there are more equations to be solved and two angles that need to be computed to determine position. However, as indicated above, the equations that may be used for this are algebraic equations with well-established solutions that will be understood by those skilled in the art. 
     Because the position of the first receiver subsystem  130  relative the SDA  110  is known a priori, the position of any object reflecting the uniquely coded transmitted signals  113  towards the first receiver subsystem  130  and more specifically the antenna (or RX 1 )  132  can be determined. With reference to  FIG. 8 , the values of the vectors (a 1 , a 2 , RTC toRX1 ) and the angles θ RX  and Ø RX1  are all known, while the values of the vectors (R TCtoTARGET , RRX 1   toTARGET , RANT 1toTARGET , RANT 2toTARGET ) and the angles θ TARGET  and Ø TARGET  are unknown. However, because the signals that reflect off of the object share a common path along RRX 1   toTARGET , the difference in arrival times at the receiver subsystem  130  is entirely due to the difference in length of the vectors RANT 1toTARGET  and RANT 2toTARGET . This information is enough to allow the angle of the target relative to the antennas  228   a - 228   n  to be calculated in the coordinate frame  5  defined by the positions of the antennas. In two dimensions, assuming |a 1 |=|a 2 |, the differential range measurements and the angle relative to the SDA center or origin  10  are related by the equation: 
       |RANT 1toTARGET |−|RANT 2toTARGET |=(| a   1   −a   2 |)sin θ TARGET .
 
     As stated above, if the local clocks of the SDA  110  and the receiver subsystem  130  are synchronized, it is possible to determine not only the relative difference in arrival time of the signals from each antennas  228   a - 228   n,  and consequently the angular position of the target  120 , but also the absolute arrival time of the transmitted signals, which, in conjunction with the known position of the receiver subsystem  130  relative to the origin  10 , gives the range of the target  120  in the coordinate system  5  determined by the location of the antennas  228  in the SDA  110 . However, unlike the calculation used to determine the range of the receiver, this calculation requires the simultaneous solution of intersecting ellipses. Methods exist, such as, for example, the gradient descent and Newton-Raphson methods, that are suitable for use with the invention to solve the resulting set of equations. Those skilled in the art will understand the manner in which these or other methods may be used to make these calculations. This two-dimensional system can be extended easily to three dimensions by using one or more additional antennas that broadcast one or more respective uniquely coded signals. 
       FIG. 9  is a schematic diagram that illustrates spatial relationships in an example arrangement of a SDA  110 , a receiver subsystem  130  with multiple antennas and a non-cooperative object or target  120  of  FIG. 1  in two dimensions. In this embodiment, two spatially distributed receivers RX 1  and RX 2  are coupled to or provided by the receiver platform  130 . A center  910  of the spatially-distributed receiver antennas RX 1  and RX 2  is located equidistant between RX 1  and RX 2  when the distance b 1  between center  910  and RX 1  is equal to the distance b 2  between center  910  and the RX 2 . Stated another way, the center  910  is the overall phase center of a spatially-distributed architecture of N antenna arrays comprising RX 1  and RX 2 . The manner in which the position of the target  120  can be calculated using the path length differences resulting from the use of both distributed SDA antennas that define origin  10  and distributed receivers that define a phase center  910  will now be described with reference to  FIG. 9 . In this example, it is assumed that the values of the vectors a 1 , a 2 , b 1 , b 2 , RTC toRXc  and angles θ RX  and Ø RX  are all known, while the values of the vectors RTC toTARGET , RANT 1toTARGET , RANT 2toTARGET , and RRX 1toTARGET  and the angles θ Target  and Ø TARGET  are unknown. However, because the signals that reflect off of the object share a common path along R RXANT1toTARGET  and a separate common path along R RXANT2toTARGET , the difference in arrival times at the respective receiver platform antennas is entirely due to the difference in the lengths of the vectors RANT 1toTARGET  and RANT 2toTARGET . This information is enough to allow the angle of the object, θ TARGET , relative to the origin  10  to be calculated in the coordinate frame  5  defined by the location of the antennas  228   a - 228   n  in the SDA of antenna arrays  112 . In two dimensions assuming |a 1 |=|a 2 |, the differential range measurements and the angle of the object relative to the origin  10  are related by the equation: 
       |RANT 1toTARGET |−|RANT 2toTARGET |=(| a   1   −a   2 |)sin θ TARGET .
 
     In two dimensions assuming b 1 =b 2 , the differential range measurements and the angle of the target relative to the center  910  of the receiver antennas RX 1  and RX 2  are related by the equation: 
       |RXANT 1toTARGET |−|RXANT 2toTARGET |=(| b   1   −b   2 |)sin φ TARGET .
 
     The length or range of the vector RXANT 1toTARGET  can be determined by the difference of the total range of the reflected versions of the uniquely coded signals received at RX 1  and the lengths of the vectors RANT 1toTARGET  and RANT 2toTARGET . Similarly, the length or range of the vector RXANT 2toTARGET  can be determined by the difference of the total range of the reflected versions of the uniquely coded signals received at RX 2  and the lengths of the vectors RANT 1toTARGET  and RANT 2toTARGET . This two-dimensional system can be extended to three dimensions. 
       FIG. 10  illustrates an example embodiment of a method  1000  that can be performed by SDA  110  to determine a position of a non-cooperative object  120  relative to the SDA  110  and to communicate the position to a platform  150  remote from the SDA  110 . The method  1000  begins with block  1002  where the SDA  110  transmits a set of uniquely identifiable signals from respective spatially-distributed antenna arrays  112 . In block  1004 , a receiver or receiver subsystem  130  located at a known position relative to the antenna arrays  112 , receives reflected versions  114  of the uniquely identifiable signals  113  reflected from the non-cooperative object  120 . In block  1006 , a processor  131  in communication with the receiver or receiver subsystem  130  determines a location of the non-cooperative object  120  relative to a coordinate system  5  defined by the antenna arrays  112 . Thereafter, as indicated in block  1008 , the SDA  110  communicates the location of the non-cooperative object  120  in the coordinate system  5  to one or more platforms  150 . 
       FIG. 11  illustrates an example embodiment of a method  1100  that can be performed by a platform  150 . The method  1100  enables the platform  150  to self-determine a platform position in a coordinate system  5  defined by a spatially-distributed architecture of antenna arrays  112  and to use information received from the spatially-distributed architecture of antenna arrays  112  regarding the location of a non-cooperative object  120 . The platform  150  uses the location of the non-cooperative object  120  to guide the platform  150  relative to the non-cooperative object  120 . The method  1100  begins with block  1102  where a first platform receiver located on the platform  150  receives a set of uniquely identifiable signals from respective spatially-distributed antenna arrays  112 . In block  1104 , a processor  151  in communication with the first platform receiver, determines one or more of position, motion and orientation of the platform in the coordinate system  5  based on characteristics of the uniquely identifiable signals  113  transmitted from the spatially-distributed architecture of antenna arrays  112 . In block  1106 , the platform  150  receives one or more information signals  115  that contain information about the location of the non-cooperative object  120  in the coordinate system  5 . In block  1108 , the processor  151  generates a guidance solution based on the position, motion and orientation of the platform  150  relative to the position and motion (if any) of the non-cooperative object  120  in the coordinate system  5 . In block  1110 , a control signal responsive to the guidance solution is forwarded to a control system on the platform  150  to direct the platform  150  relative to the non-cooperative object  120 . 
     The illustrated embodiments provide a system where a platform(s)  150  no longer has to rely on inertial guidance systems to direct the platform  150  on a trajectory or path toward the non-cooperative object or target  120 . Since the receiver subsystem  130  tracks the location of the target  120  and the platform  150  self-locates its position in a common coordinate system  5 , a processor (e.g., the processor  151 ) need not perform a coordinate translation before determining a guidance solution from these inputs. 
     In addition, since tracking of the target  120  by the receiver subsystem  130  and the platform  150  self-tracking are performed in a common reference frame  5  defined by the locations of the antennas  228   a - 228   n  in the SDA  110 , a transition of the responsibility for tracking the target or non-cooperative object  120  can be transferred to the platform  150  from the receiver subsystem  130  without a need for a coordinate translation. The hand off or transfer is efficient as a single filter can be used for both the N uniquely coded signals  113  and the reflected versions  114  of the N uniquely coded signals  113 , thereby reducing the possibility of filter transients as a result of the transition. From the time of transition until interception, the platform  150  continues to self-track while also tracking the target  120 . The same principles described above with reference to  FIGS. 5-9  apply to the operations performed by the platform  150  to self-track while also tracking the non-cooperative object or target  120 . 
     In addition, when a platform  150  is arranged with optional antennas  154  arranged to receive an indication of the location and motion (if any) of the target  120  the platform  150  continues to self-track its position and motion relative to the origin  10  of the coordinate system  5 , while the additional antenna  154  receives the target tracking information from the external source  180  and delivers it to the guidance system (not shown) of the platform  150 . For example, the position and motion of the target  120  as measured by the external source  180  may be in a coordinate system defined by or provided to an inertial sensor (not shown) of the external source  180 . The platform  150  will receive the information in that alternative coordinate system from the external source  180  and transform it into the coordinate frame  5  defined by the locations of the transmitters  228   a - 228   n  in the SDA  110 . The guidance system of the platform  150  then uses this transformed or converted information to adjust its flight path or direction, if necessary, such that it converges with the non-cooperative object  120  when so desired. Alternatively, the guidance system (not shown) of the platform  150  uses the information to adjust its path, if necessary, such that its path orbits or otherwise avoids the non-cooperative object  120  when so desired. 
       FIG. 12  includes a flow diagram illustrating an example embodiment of a method  1200  for self-determining one or more of a position, motion and orientation in a coordinate system  5  and guiding a platform relative to a remote non-cooperative object  120 . The method  1200  begins with block  1202  where a first platform receiver  552  located on the platform  500  receives a set of uniquely identifiable signals  113  transmitted from a spatially-distributed architecture (SDA) of antenna arrays  112 . In block  1204 , a processor  551  in communication with the first platform receiver  552 , determines one or more of position, motion and orientation of the platform  500  in the coordinate system  5  based on characteristics of the uniquely identifiable signals  113  transmitted from the SDA of antenna arrays  112 . In block  1206 , the platform  500  receives one or more information signals that contain information about the location of a non-cooperative object  120  relative to the platform  500 . The information signals may be transmitted from another mobile platform, or may be in the form of reflected electromagnetic energy from one or more sources. In block  1208 , the processor  551  generates a guidance solution based on the position, motion and orientation of the platform  500  relative to the position and motion (if any) of the non-cooperative object  120  in the coordinate system  5 . The one or more information signals may be combined with the self-determined position, orientation and motion of the platform  500  to also determine the position, motion and orientation of the non-cooperative object  120 . In block  1210 , a control signal responsive to the guidance solution is applied to a guidance system  556  to direct the platform  500  relative to the non-cooperative object  120 . 
     In block  1212 , the platform  500  receives an informational signal  115  identifying a present location of the SDA of antenna arrays  112 . In block  1214 , the platform  500  is programmed or configured to confirm and/or adjust a present location of the SDA of antenna arrays  112  and a platform determined position in the coordinate system  5 . As indicated in block  1216 , the platform  500  may optionally be arranged to communicate an informational signal  1420  identifying a location of the non-cooperative object  120  to proximally located receivers. 
     As indicated in  FIG. 12 , the method  1200  is arranged such that the functions and operations associated with blocks  1202 - 1216  may be repeated as may be desired to navigate or otherwise guide the platform  500  relative to the non-cooperative object or target  120  in the coordinate system  5  and to guide and direct one or more optional interceptor platforms  600  near the platform  500 . 
       FIG. 13  includes a flow diagram illustrating an example embodiment of a method  1300  for self-determining one or more of a position, motion and orientation in a coordinate system  5  and guiding a platform relative to a remote non-cooperative object  120 . The method  1300  begins with block  1302  where a first platform receiver  552  located on the platform  500  receives a set of uniquely identifiable signals  113  transmitted from a spatially-distributed architecture (SDA) of antenna arrays  112 . In block  1304 , a processor  551  in communication with the first platform receiver  552 , determines one or more of position, motion and orientation of the platform  500  in the coordinate system  5  based on characteristics of the uniquely identifiable signals  113  transmitted from the SDA of antenna arrays  112 . In block  1306 , the platform  500  receives one or more information signals that contain information about the location of a non-cooperative object  120  relative to the platform  500 . The information signals may be transmitted from another mobile platform, or may be in the form of reflected electromagnetic energy from one or more sources. As illustrated in  FIG. 14 , the information signal may be in the form of reflected electromagnetic energy  1402  that is received by a sensor  1460  or a sensor subsystem supported by the platform  500 . In block  1308 , the processor  551  generates a guidance solution based on the position, motion and orientation of the platform  500  relative to the position and motion (if any) of the non-cooperative object  120  in the coordinate system  5 . The one or more information signals may be combined with the self-determined position, orientation and motion of the platform  500  to also determine the position, motion and orientation of the non-cooperative object  120 . In block  1310 , a control signal responsive to the guidance solution is applied to a guidance system  556  to direct the platform  500  relative to the non-cooperative object  120 . 
     In block  1312 , the platform  500  generates a platform unique signal different from any of the uniquely identifiable signals transmitted from the SDA of antenna arrays  112  and different from other mobile platforms in the system of platforms  1400 . In block  1314 , the platform is arranged to transmit the platform unique signal such as in information signal  1420  toward one or more interceptor platforms  600 . In addition, as indicated in block  1316 , the platform  500  is arranged to transmit a respective information signal identifying a present location of the platform  500 . 
     As indicated in  FIG. 13 , the method  1300  is arranged such that the functions and operations associated with blocks  1302 - 1316  may be repeated as may be desired to navigate or otherwise guide the platform  500  relative to the non-cooperative object or target  120  in the coordinate system  5  and to guide and direct one or more optional interceptor platforms  600  near the platform  500 . 
       FIG. 14  is a schematic diagram that illustrates an alternative embodiment of a system of platforms  1400  including a group of various platform types navigating in one coordinate system. The improved tracking and/or guidance system includes a pilot platform  1445  with a spatially-distributed architecture (SDA)  110  or signal generation sub-system  111  that is separated or remotely located from a non-cooperative object or target  120 . In the illustrated embodiment, the pilot platform  1445  is collocated or proximally located to a receiver subsystem or first receiver  130 . A first or targeting platform  500 , and one or more second or interceptor platforms  600   a - 600   n  are separate from the pilot platform  1445  with the targeting platform  500  within signal range of the N uniquely coded transmit signals  113  and one or more informational signals  115  communicated wirelessly from the pilot platform  1445 . 
     As indicated schematically in  FIG. 14 , the SDA  110  defines a coordinate system  5 . The coordinate system  5  includes an origin  10  where an X-axis  12 , a Y-axis  13 , and a Z-axis  14  meet. As further indicated schematically in  FIG. 1 , the X-axis  12  is orthogonal or approximately orthogonal to both of the Y-axis  13  and the Z-axis  14 . In addition, the Y-axis  13  is orthogonal or approximately orthogonal to the Z-axis  14 . The coordinate system  5  provides a mechanism to spatially define the relative location and orientation of items in the system of platforms  1400 . While the origin  10  may be defined at any location within or about the SDA  110 , the origin  10  is preferably located at the phase center of the N antenna arrays  112  forming the SDA  110 . 
     In the illustrated embodiment, the targeting platform  500  is shifted or translated in one or more of the X, Y and Z directions with respect to the coordinate system  5 . 
     As described in association with the embodiment illustrated in  FIG. 1 , the SDA  110  generates and controllably transmits N uniquely coded signals  113  where N is a positive integer greater than or equal to two. The N uniquely coded signals  113 , generated by and transmitted from the SDA  110 , impinge or directly encounter the platform  500 . In the present embodiment the SDA  110  may be a fixed station on the ground or a moving station disposed on a moving platform such as, for example, a ship, an airplane, a flying drone, a truck, a tank, or any other type of suitable vehicle (not shown). In addition to transmitting the uniquely coded signals from the SDA  110 , the pilot platform  1445  generates and transmits one or more information signal(s)  115  that periodically identify a present location of the pilot platform  1445  in a coordinate system. For example, the information signal(s)  115  may include latitude, a longitude and an altitude corresponding to the origin  10  of the coordinate system  5 . 
     In the example embodiment, the first or targeting platform  500  is arranged with processing circuitry or a processor  551 , memory  555 , one or more antennas  552 , transmit and receive subsystems or a transceiver subsystem  553 , one or more optional antennas  554 , a guidance system  556  and a sensor system  1460 . The targeting platform  500  may be fixed to one or more of a missile, a projectile, a ship, an airplane, a flying drone, a truck, a tank, or any other type of suitable vehicle or even a relatively small portable device (not shown). When the targeting platform  500  is coupled to or part of a projectile, the platform  500  may be dropped, launched, expelled or otherwise separated from a ship, airplane, drone, or land-based vehicle. The guidance system  556  is arranged with one or more control systems, an inertial navigation system and is optionally arranged with a propulsion system. The one or more antennas  552  receive the N uniquely coded transmit signals  113  and the periodic information signal(s)  115  transmitted by the SDA  110 . The received signals are bandwidth filtered, downconverted in frequency and demodulated by the transceiver subsystem  553  before being forwarded to the processor  551 . The memory  555  includes one or more logic modules and data values (not shown) that when controllably retrieved and executed by the processor  551  enable the processor  551 , in response to information derived from the N uniquely coded signals  113  as received at the antennas  552 , to self-determine a position of the platform  500  in the coordinate system  5 . Changes in the location of the platform  500  relative to the SDA  110  may also be determined by the processor  551  or may be determined solely in an inertial navigation system (INS) coupled to or otherwise provided in the guidance system  556 . 
     The sensor system  1460 , which may be an optical system or a radar system, receives one or more wireless signals that include information regarding the relative position or location of the non-cooperative object  120  with respect to the targeting platform  500 . An optical sensor system may include a photosensitive receiver and optical elements arranged to intercept, collimate and/or focus the received optical signal. Alternatively, the optical sensor system may include or control a light source for illuminating the non-cooperative object or target  120 . When such a light source is integrated with the sensor system  1460 , the sensor system will include one or more emitters and corresponding optical elements to collect, collimate and/or focus emitted light toward the non-cooperative object or target  120 . 
     In addition, or as part of a preliminary target identification or acquisition process, one or more of the antennas  552  or a dedicated optional antenna  554  may receive information identifying the location and motion (if any) of the pilot platform  1445  as communicated by the SDA  110  via the communication link  115 . The targeting platform  500  may further receive information from other communication links transmitted from alternative signal sources (not shown) identifying or locating a search region within which the targeting platform  500  can observe the non-cooperating object or target  120 . Thus, one or more logic modules and data values can be communicated to and or stored on the targeting platform  500  and transferred to the processor  551  to enable any one of the previously described operational modes. 
     In one example mode, the first or targeting platform  500  is programmed or otherwise instructed via one or more information signals  115  to acquire an optical signal or radar signal reflected by the non-cooperative object or target  120  and to maintain a pre-defined relationship over time with respect to the non-cooperative object or target  120 . For example, the targeting platform  500  may be programmed or otherwise instructed to determine the vector, V TAR , defined by the incident reflected optical or radar beam to intercept and contact the target  120 . In another example mode of operation, the targeting platform  500  may be programmed or otherwise instructed to navigate about the non-cooperative object or target  120  in a desired way. 
     In addition, the one or more antennas  552  and/or the optional antenna  554  will periodically or intermittently receive a signal that may be forwarded to one or both of the guidance system  556  and the processor  551  from the SDA of antenna arrays  110  to provide updated information regarding the location of the targeting platform  500  relative to the coordinate system  5  defined by the SDA of antenna arrays  110 . In response, the INS of the guidance system  556  may be monitored for accuracy and/or adjusted as may be desired using information provided in the information signal  115  and information such as a range and angle determined from the time of arrival and phase differences of the N uniquely coded transmit signals  113 . In addition or alternatively, the guidance system  556  and/or the processor  551  may generate a modified control signal using a combination of information from the INS and the signal from the SDA of antenna arrays  110  to ensure that the targeting platform  500  is accurately positioned on a course to intercept, orbit or otherwise navigate with respect to the non-cooperative object or target  120 . 
     In the example embodiment, the second or interceptor platform(s)  600   a - 600   n  is arranged with processing circuitry or a processor, memory, one or more antennas, and a guidance system. The interceptor platform(s)  600   a - 600   n  may be fixed to one or more of a missile, a projectile, a ship, an airplane, a flying drone, a truck, a tank, or any other type of suitable vehicle or even a relatively small portable device (not shown). When the interceptor platform(s)  600   a - 600   n  is coupled to or part of a projectile, the platform  600   a - 600   n  may be dropped, launched, expelled or otherwise separated from a ship, airplane, drone, or land-based vehicle. The guidance system is arranged with one or more control systems, an inertial navigation system and is optionally arranged with a propulsion system. The one or more antennas may receive the N uniquely coded transmit signals  113  transmitted by the SDA  110  or may navigate based on their respective INS as periodically confirmed and/or updated with information broadcast from the targeting platform  500  via the information signal  1420 . The interceptor platforms  600   a - 600   n  may further receive vector V TAR . In response, the guidance system  656  may generate a modified control signal to ensure that the respective interceptor platform  600   a - 600   n  is on a course to intercept the non-cooperative object or target  120 . 
       FIG. 15  is a schematic diagram that illustrates another alternative embodiment of a system of platforms  1500  including a group of mobile platforms  700   a - 700   n  and a separate group of (interceptor) platforms  150   a - 150   n  navigating in multiple coordinate systems. The improved tracking and/or guidance system includes a first or primary spatially-distributed architecture (SDA) or signal generation sub-system  110  that is separated or remotely located from a non-cooperative object or target  120 . In the illustrated embodiment, the SDA  110  is arranged or located to the same side of each of the non-cooperative object or target  120 , and one or more mobile platforms  700   a - 700   n.  The system of platforms  1500  is not so limited and in modified environments the SDA  110  will be spatially located in other relationships with respect to the receiver subsystem  130 , platforms  700   a - 700   n,  and the non-cooperative object or target  120 . 
     As indicated schematically in  FIG. 15 , the SDA  110  defines a first coordinate system  5 . The first coordinate system  5  includes an origin  10  where an X-axis  12 , a Y-axis  13 , and a Z-axis  14  meet. As further indicated schematically in  FIG. 15 , the X-axis  12  is orthogonal or approximately orthogonal to both of the Y-axis  13  and the Z-axis  14 . In addition, the Y-axis  13  is orthogonal or approximately orthogonal to the Z-axis  14 . The first coordinate system  5  provides a mechanism to spatially define the relative location and orientation of elements in the system of platforms  1500 . While the origin  10  may be defined at any location within or about the SDA  110 , the origin  10  is preferably located at the phase center of the N antenna arrays forming the SDA  110 . 
     Similarly, the set of mobile platforms  700   a - 700   n  forms a secondary spatially-distributed architecture of antenna arrays  1510  that identifies a secondary second coordinate system  5 ′. In the illustrated embodiment, the second coordinate system  5 ′ is shifted or translated in one or more of the X, Y and Z directions with respect to the first coordinate system  5  defined by the SDA  110 . In the illustrated embodiment the X, Y and Z directions of the separate coordinate systems are parallel to one another. This relationship reduces the complexity of coordinate system translations. However, the system of platforms  1500  is not so limited and other spatial orientations (relationships) are possible and contemplated. 
     In the present embodiment the SDA  110  may be a fixed station on the ground or a moving station disposed on a moving platform such as, for example, a ship, an airplane, a flying drone, a truck, a tank, or any other type of suitable vehicle (not shown). The SDA  110  and the receiver subsystem  130  operate as described in association with the embodiment illustrated in  FIG. 1 . Together, the SDA  110  and the receiver subsystem  130  determine a position of the interceptor platform(s)  700   a - 700   n  in the coordinate system  5 . As further described above the interceptor platforms  700   a - 700   n  may be arranged to self-determine a respective location, orientation and motion (if any) in the coordinate system  5 . 
     In the example embodiment illustrated in  FIG. 15 , the mobile platform  700   a  is arranged with processing circuitry or a processor  751 , memory  755 , one or more antennas  752 , one or more antennas  754 , transceiver  753 , a guidance system  756  and a signal generator  757 . The mobile platform  700   a  may be fixed to one or more of a missile, a projectile, a ship, an airplane, a flying drone, a truck, a tank, or any other type of suitable vehicle or even a relatively small portable device (not shown). The mobile platform  700   a  may be located within line-of-sight of the non-cooperative object or target  120 , while the SDA  110  and the receiver  130  are not. 
     When the mobile platform  700   a  is coupled to or part of a projectile, the platform  700   a  may be dropped, launched, expelled or otherwise separated from a ship, airplane, drone, or land-based vehicle. The guidance system  756  is arranged with one or more control systems, an inertial navigation system and is optionally arranged with a propulsion system. The one or more antennas  752  receive the N uniquely coded transmit signals  113  transmitted by the SDA  110 . The memory  755  includes one or more logic modules and data values (not shown) that when controllably retrieved and executed by the processor  751  enable the processor  751 , in response to information derived from the N uniquely coded signals  113  as received at the antennas  752 , to self-determine a position of the mobile platform  700   a  in the coordinate system  5 . Changes in the location of the platform  700   a  relative to the SDA  110  may also be determined by the processor  751  or may be determined solely in an inertial navigation system (INS) coupled to or otherwise provided in the guidance system  756 . As illustrated in  FIG. 15  the INS may be relied on to define a second coordinate system  5 ′ with an origin  10 ′ coexistent or co-located with one or more physical surfaces of the interceptor platform  700 . 
     The mobile platform(s)  700   a - 700   n  are provided with the signal generator  757  to create and forward a modulated signal to the one or more antennas  754 . The modulated signal may be bandwidth filtered and upconverted in frequency in the transceiver  753  before being communicated to and transmitted by the one or more antennas  754 . The modulated signal is uniquely associated with the respective instance of the mobile platform  700   a - 700   n.  As indicated in  FIG. 15 , M uniquely coded transmit signals  1413  are transmitted toward the non-cooperative object or target  120  and Q reflected versions of the M unique platform transmitted signals  1414  are reflected back to the one or more antennas  754 . As described in connection with the embodiment illustrated in  FIG. 1 , time of arrival and phase differences identified in the Q reflected versions of the M uniquely coded or uniquely identifiable platform generated signals may be processed in the processor  751  to determine a range and vector direction in the coordinate system  5 ′. 
     Thereafter, processor  751  in communication with a platform receiver  754  determines one or more a position, motion and an orientation of the platform  700   a  in a coordinate system  5 ′ defined by the platform  700   a.  In this regard, the platform  700   a  may be relying on information provided by an INS in a guidance control system or guidance and propulsion system  756 . Such an INS may provide inaccurate positional information in any one or more of the X, Y and Z axes. When the INS is used as a basis for establishing the coordinate system  5 ′, erroneous INS information will result in additional errors if the position of platform  700   a  is used to direct or assist one or more platforms  700   n  with respect to the non-cooperative object or target  120 . Accordingly, the pilot platform  1445  periodically sends one or more information signals  115  containing a present location of the pilot platform  1445  in the coordinate system  5  to the platform  700   a.  In response, the processor  751  executes software or firmware that together with the location data and characteristics of the N uniquely coded transmit signals  113  identifies when the INS information in the guidance system  756  is in need of correction. When this is the case, the location of the platform  700   a  is replaced. 
     The same principles described above with reference to  FIGS. 5-9  apply to the operations performed by the platforms to self-track while also tracking the non-cooperative object or target  120 . Alternatively, a signal or signals from a targeting platform and/or a separate and distinct system may provide information about the location of a target. 
     In addition, when platforms  700   a - 700   n  are configured with antenna arrays  754  arranged to transmit the locally generated uniquely coded signals from the signal generator  757  these signals produce a remote or second or secondary spatially-distributed architecture of antenna arrays  1510  different from the (first or primary) SDA  110  in the pilot platform  1445 . The remote or secondary SDA of antenna arrays  1510  in conjunction with a set of uniquely identifiable signals transmitted from each of the separate antenna arrays can be used to guide or navigate one or more interceptor platforms  150   a - 150   n  when so desired. 
     Such mobile platforms  700   a - 700   n  and interceptor platforms  150   a - 150   n  may share information concerning the location, orientation and motion (if any) of the non-cooperative object in addition to information concerning their respective location in either the coordinate system  5  defined by the primary spatially-distributed architecture of antenna arrays  110  or the coordinate system  5 ′ defined by the secondary spatially distributed architecture of antenna arrays  1510  as desired. A two-way radio-frequency communication channel  1520  is arranged to support such transfers of information including location, orientation and motion of the non-cooperative object and/or a respective self-determined location, orientation and motion of a platform between one or more mobile platforms  700   a - 700   n  and one or more interceptor platforms  150   a - 150   n.    
     It should be noted that this disclosure has been presented with reference to one or more exemplary or described embodiments for the purpose of demonstrating principles and concepts. The claimed systems, methods and computer-readable media are not limited to these example embodiments. As will be understood by persons skilled in the art, in view of the description provided herein, many variations may be made to the example embodiments described herein and all such variations are within the scope of the invention. For example, a function or capability introduced and described in association with one of the exemplary embodiments may be introduced or applied in other arrangements where improvements to platform guidance or navigation may be desired. 
     
       
         
           
               
             
               
                   
               
               
                 REFERENCE SYMBOLS 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                  5, 5′ 
                 coordinate system 
               
               
                   
                 10, 10′ 
                 origin 
               
               
                   
                 12, 12′ 
                 X-axis 
               
               
                   
                 13, 13′ 
                 Y-axis 
               
               
                   
                 14, 14′ 
                 Z-axis 
               
               
                   
                  100 
                 environment 
               
               
                   
                  110 
                 spatially-distributed architecture 
               
               
                   
                  110′ 
                 spatially-distributed architecture 
               
               
                   
                  111 
                 signal generator 
               
               
                   
                  112 
                 N antenna arrays 
               
               
                   
                  113 
                 N uniquely coded signals 
               
               
                   
                  114 
                 reflections (of coded signals) 
               
               
                   
                  115 
                 information signal 
               
               
                   
                  117 
                 N uniquely coded signals (modified) 
               
               
                   
                  120 
                 non-cooperative object (target) 
               
               
                   
                  122 
                 cooperative object 
               
               
                   
                  130 
                 first receiver subsystem 
               
               
                   
                  131 
                 processor 
               
               
                   
                  132 
                 antenna(s) 
               
               
                   
                  135 
                 memory 
               
               
                   
                  138 
                 signal generator 
               
               
                   
                  139 
                 connection 
               
               
                   
                  140 
                 signal 
               
               
                   
                  150 
                 platform(s) 
               
               
                   
                  151 
                 processor 
               
               
                   
                  152 
                 antenna(s) 
               
               
                   
                  154 
                 antenna (optional) 
               
               
                   
                  155 
                 memory 
               
               
                   
                  180 
                 alternate signal source 
               
               
                   
                  185 
                 information signal 
               
               
                   
                  201 
                 SDA subsystem 
               
               
                   
                  202 
                 processor 
               
               
                   
                  203 
                 input/output interface 
               
               
                   
                  204 
                 clock generator 
               
               
                   
                  205 
                 memory 
               
               
                   
                  206 
                 bus 
               
               
                   
                  211 
                 signal generator 
               
               
                   
                  212 
                 Local info. store 
               
               
                   
                  213 
                 TX module 
               
               
                   
                  214 
                 RX module 
               
               
                   
                  215 
                 code store/signal gen. 
               
               
                   
                  216 
                 connection 
               
               
                   
                  217 
                 connection 
               
               
                   
                  220 
                 SDA circuitry 
               
               
                   
                  220′ 
                 SDA circuitry 
               
               
                   
                  221 
                 TX circuitry 
               
               
                   
                  221′ 
                 TX circuitry 
               
               
                   
                  222 
                 RX circuitry 
               
               
                   
                  223 
                 master oscillator 
               
               
                   
                  224 
                 synchronization clock 
               
               
                   
                  225 
                 connection 
               
               
                   
                  226 
                 TX signal generator 
               
               
                   
                  228 
                 N antenna arrays 
               
               
                   
                  330 
                 receiver platform 
               
               
                   
                  330′ 
                 receiver platform 
               
               
                   
                  331 
                 processor 
               
               
                   
                  331′ 
                 processor 
               
               
                   
                  332 
                 bus 
               
               
                   
                  333 
                 input/output interface 
               
               
                   
                  334 
                 clock generator 
               
               
                   
                  335 
                 memory 
               
               
                   
                  336 
                 location module 
               
               
                   
                  337 
                 motion module 
               
               
                   
                  338 
                 information signal logic 
               
               
                   
                  339 
                 local info store 
               
               
                   
                  342 
                 connection 
               
               
                   
                  350 
                 demodulator 
               
               
                   
                  360 
                 matched filter bank 
               
               
                   
                  400 
                 platform 
               
               
                   
                  400′ 
                 platform 
               
               
                   
                  402 
                 phase-locked loop (PLL) 
               
               
                   
                  404 
                 local oscillator 
               
               
                   
                  405 
                 summing node 
               
               
                   
                  406 
                 clock 
               
               
                   
                  410 
                 RX/demodulator 
               
               
                   
                  411 
                 processor 
               
               
                   
                  411′ 
                 processor 
               
               
                   
                  412 
                 bus 
               
               
                   
                  413 
                 input/output interface 
               
               
                   
                  414 
                 clock generator 
               
               
                   
                  415 
                 memory 
               
               
                   
                  416 
                 connection 
               
               
                   
                  417 
                 connection 
               
               
                   
                  420 
                 matched filter bank 
               
               
                   
                  431 
                 location module 
               
               
                   
                  432 
                 motion module 
               
               
                   
                  433 
                 orientation module 
               
               
                   
                  434 
                 second module (nav./guidance) 
               
               
                   
                  435 
                 signal generator 
               
               
                   
                  436 
                 conversion module 
               
               
                   
                  437 
                 coordination module 
               
               
                   
                  438 
                 local info store 
               
               
                   
                  450 
                 platform circuitry 
               
               
                   
                  460 
                 receiver 
               
               
                   
                  465 
                 antenna 
               
               
                   
                  500 
                 platform 
               
               
                   
                  551 
                 processor 
               
               
                   
                  552 
                 antenna/rcvr. 
               
               
                   
                  553 
                 transceiver circuitry 
               
               
                   
                  554 
                 ant./rcvr. (opt.) 
               
               
                   
                  555 
                 memory 
               
               
                   
                  556 
                 guidance system 
               
               
                   
                 600a-600n 
                 platform(s) 
               
               
                   
                 700a-700n 
                 platform(s) 
               
               
                   
                  751 
                 processor 
               
               
                   
                  752 
                 antenna/rcvr. 
               
               
                   
                  754 
                 antenna/rcvr. 
               
               
                   
                  755 
                 memory 
               
               
                   
                  756 
                 guidance system 
               
               
                   
                  757 
                 signal generator 
               
               
                   
                  910 
                 RX array (center) 
               
               
                   
                 1000 
                 SDA method 
               
               
                   
                 1002-1008 
                 method steps 
               
               
                   
                 1100 
                 platform method 
               
               
                   
                 1102-1110 
                 platform steps 
               
               
                   
                 1200 
                 platform method 
               
               
                   
                 1202-1216 
                 platform steps 
               
               
                   
                 1300 
                 platform method 
               
               
                   
                 1302-1316 
                 platform steps 
               
               
                   
                 1400 
                 system of platforms 
               
               
                   
                 1402 
                 electromagnetic energy 
               
               
                   
                 1405 
                 vector 
               
               
                   
                 1413 
                 M coded TX signals 
               
               
                   
                 1414 
                 Q reflections of M Tx signals 
               
               
                   
                 1420 
                 information signal 
               
               
                   
                 1445 
                 pilot platform 
               
               
                   
                 1460 
                 sensor/sensor subsystem 
               
               
                   
                 1500 
                 system of platforms 
               
               
                   
                 1510 
                 secondary spatially-distributed architecture 
               
               
                   
                 1520 
                 two-way communication channel