Abstract:
A weapons system is disclosed that provides hot-start navigational information to the Global-Positioning-System receivers on missiles prior to flight. The system comprises a Global-Positioning-System receiver that uses a classified red cryptographic key to decode the P(Y) signal from one or more of the Global-Positioning-System constellation of satellites. Once the P(Y) signal is decoded, one or more characteristics (e.g., the PRN code synchronization, the Doppler shift, the modulation bit sequence, etc.) of the signal is derived. These characteristics of the signal—and some other information including a black cryptographic key that comprises the red cryptographic key—are then provided to the Global-Positioning-System receivers on missiles prior to flight. By giving the missiles this information, the missiles are able to acquire the P(Y) signals themselves more quickly than they otherwise could, which enables them to determine their position more quickly than they otherwise could.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. provisional patent application Ser. No. 60/493,827, filed Aug. 8, 2003, entitled “VLS Global-Positioning-System Integrator (VGI) with SAASM,” which is also incorporated by reference. 
     
    
     STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH  
       [[0002]]     This invention was made with Government support under Contracts No. N00024-00-C-5486 and N00024-03-C-6110, awarded by the Department of the Navy. The Government has certain rights in this invention. 
     
    
     FIELD OF THE INVENTION  
       [0003]     The present invention relates to weapons systems in general, and, in particular, to an electronics system that provides “hot-start” navigational information to the Global-Positioning-System receivers on missiles prior to flight.  
       BACKGROUND OF THE INVENTION  
       [0004]     Weapons systems in the prior art have provided “hot-start” navigational information to the Global-Positioning-System receivers on missiles prior to flight, but these systems have relied on complex wiring and multiple interfaces to provide the information to the receivers. Therefore, the need exists for an improved weapons system for providing hot-start navigational information to the Global-Positioning-System receivers on missiles prior to flight, without some of the costs and disadvantages in the prior art.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention enables a weapons system to provide “hot-start” navigational information to the Global-Positioning-System receivers on missiles prior to flight without some of the costs and disadvantages associated with distribution systems in the prior art. Although the illustrative embodiment of the present invention is a weapons system, it will be clear to those skilled in the art, after reading this specification, how to make and use embodiments of the present invention in non-weapons systems, such as civilian navigation systems, time distribution systems, and banking systems.  
         [0006]     The illustrative embodiment is a weapons system that comprises a Global-Positioning-System data integrator and distribution system. The Global-Positioning-System data integrator comprises a Global-Positioning-System receiver that uses a classified red cryptographic key to decode the P(Y) signal from one or more Global-Positioning-System satellites. Once the P(Y) signal is decoded, one or more characteristics (e.g., the PRN code synchronization, the Doppler shift, the modulation bit sequence, etc.) of the signal is derived. The “hot start” navigational information comprises these characteristics of the signal—and some other information including a black cryptographic key from which the red cryptographic key is derivable. By giving the “hot start” navigational information to the Global-Positioning-System receivers on the missiles prior to flight, the missiles are able to acquire the P(Y) signals themselves more quickly than they otherwise could, which enables them to determine their position more quickly than they otherwise could.  
         [0007]     The illustrative embodiment comprises: a first Global-Positioning-System receiver for receiving (i) a black cryptographic key from which a red cryptographic key is derivable and (ii) a signal from a Global-Positioning-System satellite, and for deriving a characteristic of the signal based on the red cryptographic key; and a transmitter for transmitting the characteristic and the black cryptographic key to a second Global-Positioning-System receiver. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  depicts a schematic diagram of missile platform  100 , in accordance with the illustrative embodiment of the present invention.  
         [0009]      FIG. 2  depicts a block diagram of the salient components of weapons control system  200 , in accordance with the illustrative embodiment of the present invention.  
         [0010]      FIG. 3  depicts a block diagram of the salient components of Global-Positioning-System Integrator  202 , in accordance with the illustrative embodiment of the present invention.  
         [0011]      FIG. 4  depicts a block diagram of the salient components of power system  203 , in accordance with the illustrative embodiment of the present invention.  
         [0012]      FIG. 5  depicts a block diagram of the salient components of Missile Bank  204 , in accordance with the illustrative embodiment of the present invention.  
         [0013]      FIG. 6  depicts a block diagram of the salient components of missile  102 - i - j , in accordance with the illustrative embodiment of the present invention.  
         [0014]      FIG. 7  depicts a flowchart of the salient tasks of weapons control system  200 , in accordance with the illustrative embodiment of the present invention.  
         [0015]      FIG. 8  depicts a flowchart of task  702 , in accordance with the illustrative embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]     For the purposes of the disclosure and claims, the term “red cryptographic key” is defined as a string that is used recover a P(Y) signal from a Global-Positioning-System satellite.  
         [0017]     For the purposes of the disclosure and claims, the term “black cryptographic key” is defined as an encrypted red cryptographic key.  
         [0018]     For the purposes of the disclosure and claims, the term “hot-start navigation information” is defined as any information that could enable or expedite a Global-Positioning-System receiver to acquire or decode the signals from a Global-Positioning-System satellite.  
         [0019]      FIG. 1  depicts a schematic diagram of the salient components of missile platform  100 , in accordance with the illustrative embodiment of the present invention. Missile platform  100  comprises missile cruiser  101 , Global-Positioning-System satellite constellation  104 , and weapons control system  200  (not shown in  FIG. 1 ), which itself comprises missile  102 - 1 - 1  and Global-Positioning-System antenna  103 .  
         [0020]     Missile cruiser  101  is a ship that is used to transport, arm, and launch missiles from a location at sea. Except for those portions of weapons control system  200  described below, it will be clear to those skilled in the art how to make and use missile cruiser  101 .  
         [0021]     Missile  102 - 1 - 1  is one of a plurality of missiles that are transported, armed, and launched by missile cruiser  101 . Missile  102 - 1 - 1  is described in detail below and with respect to  FIGS. 2 through 8 .  
         [0022]     Global-Positioning-System antenna  103  is used to receive signals from satellite constellation  104  in well-known fashion. It will be clear to those skilled in the art how to make and use Global-Positioning-System antenna  103 .  
         [0023]     Satellite constellation  104  comprises the satellites that are part of the Global-Positioning-System that transmit signals to receivers (e.g., on board ship  101 , within missile  102 - 1 - 1 , etc.) for the purpose of determining the position of those receivers. It will be clear to those skilled in the art how to make and use satellite constellation  104 .  
         [0024]      FIG. 2  depicts a block diagram of the salient components of weapons control system  200 , in accordance with the illustrative embodiment of the present invention. Weapons control system  200  comprises launch control system  201 , Global-Positioning-System Integrator  202 , power system  203 , and Missile Bank  204 , interconnected as shown. Weapons control system  200  is used to arm and launch missiles by performing the tasks described below and with respect to  FIGS. 7 and 8 .  
         [0025]     Launch control system  201  is the operator interface for weapons control system  200 . Launch control system  201  translates operator commands into control signals that it transmits to Global-Positioning-System Integrator  202  and power system  203 . The control signals are used to select, arm, program, and fire a specified missile or missiles (e.g., missile  102 - 1 - 1 , etc.).  
         [0026]     Global-Positioning-System integrator  202  is circuitry that accepts control signals from launch control system  201  to affect which missiles receive the “hot-start” navigational information.  
         [0027]     Some of the information that Global-Positioning-System integrator  202  receives from Global-Positioning-System satellite constellation  104  is encrypted. To decrypt the encrypted information, Global-Positioning-System Integrator  202  uses an encryption key that it receives from a key source (not shown). Global-Positioning-System integrator  202  is described in detail below and with respect to  FIGS. 3, 5 ,  7  and  8 .  
         [0028]     Power system  203  is a power supply that accepts control signals from launch control system  201  to affect which missiles to power (and, therefore, to accept the hot-start navigation information transmitted by Global-Positioning-System integrator  202 ). Power system  203  is described in detail below and with respect to  FIGS. 4, 5 ,  7  and  8 .  
         [0029]     Missile Bank  204  is a bank of eight missiles, missiles  102 - 1 - 1  through  102 - 2 - 4 . When one or more of the missiles in Missile Bank  204  receives the confluence of both power from power system  203  and hot-start navigation information from Global-Positioning-System integrator  202 , then the Global-Positioning-System receiver on that missile is enabled to accept and store the hot-start navigational information. Although Missile Bank  204  has 8 missiles in the illustrative embodiment, it will be clear to those skilled in the art, after reading this specification, how to make and use alternative embodiments of the present invention that comprise any number of missiles. Missile Bank  204  is described in detail below and with respect to  FIG. 5 .  
         [0030]      FIG. 3  depicts a block diagram of the salient components of Global-Positioning-System Integrator  202 , in accordance with the illustrative embodiment of the present invention. Global-Positioning-System Integrator  202  comprises processor  301 , Global-Positioning-System receiver  302 , memory  303 , transmitters  304 - 1  and  304 - 2 , splitters  305 - 1  and  305 - 2 , optical fibers  306 - 1  and  306 - 2 , optical fibers  307 - 1 - 1  through  307 - 1 - 4 , and optical fibers  307 - 2 - 1  through  307 - 2 - 4 , interconnected as shown.  
         [0031]     Processor  301  is a general-purpose processor that is capable of receiving control signals from launch control system  201 , of receiving a black cryptographic key from a red cryptographic key source, of reading data from and writing data to Global-Positioning-System receiver  302 , of reading data from and writing data into memory  303 , and of transferring to transmitters  304 - 1  and  304 - 2  (i) the black cryptographic key and (ii) one or more characteristics (e.g., Doppler shift estimate, PRN code synchronization estimate, modulation bit sequence, etc.) of a signal from a Global-Positioning-System satellite of satellite constellation  104 . U.S. Pat. No. 6,281,837 by R. E. Richton and G. Vannucci is incorporated by reference and teaches how to determine the characteristics of a signal from a Global-Positioning-System satellite of satellite constellation  104 .  
         [0032]     In some alternative embodiments of the present invention, processor  301  is be a special-purpose processor. In either case, it will be clear to those skilled in the art, after reading this disclosure, how to make and use processor  301 .  
         [0033]     Processor  301  receives in well-known fashion (e.g., via a data transfer device [DTD] interface, etc.) a black cryptographic key from which a red cryptographic key is derivable. In accordance with the illustrative embodiment, the black cryptographic key is encrypted with a public key cryptosystem, as is well known in the art. Processor  301  then transfers the black cryptographic key to Global-Positioning-System receiver  302 .  
         [0034]     Global-Positioning-System receiver  302  receives a signal from one or more Global-Positioning-System satellites in satellite constellation  104 , in well-known fashion.  
         [0035]     Global-Positioning-System receiver  302  also receives the black cryptographic key comprising the red cryptographic key from processor  301 . Global-Positioning-System receiver  302  decrypts the red cryptographic key from the black cryptographic key, in well-known fashion, and then uses it to derive one or more characteristics of the received signal as described in U.S. Pat. No. 6,281,837. It will be clear to those skilled in the art, after reading this disclosure, how to make and use receiver  302 .  
         [0036]     Memory  303  is a volatile dynamic random-access memory (DRAM) that stores the hot-start navigational information, in well-known fashion, and the black cryptographic key that comprises the red cryptographic key. Periodically or sporadically, processor  301  zeroes out the specific location in memory  303  in which the black cryptographic key has been stored. It will be clear to those skilled in the art, after reading this disclosure, how to make and use memory  303 .  
         [0037]     Transmitter  304 - i , wherein i is selected from the set {1, 2}, transmits the hot-start navigational information to splitter  305 - i  via optical fiber  306 - i . Although there are two transmitters in the illustrative embodiment, it will be clear to those skilled in the art, after reading this specification, how to make and use alternative embodiments of the present invention that comprise any number of transmitters. It will be clear to those skilled in the art, after reading this specification, how to make and use embodiments of the present invention that have any number of transmitters and splitters.  
         [0038]     The hot-start navigational information comprises: 
        Global-Positioning-System almanac, ephemerides, and complementary navigation [COMPNAV] for the satellites which a missile might be able to view during its flight, and     the time-mark strobe and the time-mark data, which describes where in time the time-mark strobe occurs, and     the black cryptographic key that comprises the red cryptographic key, which red cryptographic key enables the Global-Positioning-System receiver to decode P(Y) signals. 
 
 The almanac and ephemeredes information described in U.S. Pat. Ser. No. 6,114,991, which is incorporated by reference. It will be clear to those skilled in the art, after reading this specification, how to make and use transmitter  304 - i.  
       
 
         [0043]     Splitter  305 - i  is an optical splitter that replicates and distributes the hot-start navigational information received from transmitter  304 - i . In accordance with the illustrative embodiment, splitter  305 - i  distributes the hot-start navigational information to four missiles in missile bank  204 . Although there are two splitters in the illustrative embodiment, it will be clear to those skilled in the art, after reading this specification, how to make and use alternative embodiments of the present invention that comprise any number of splitters. Furthermore, although the splitters in the illustrative embodiment have a 1-to 4 fan out, it will be clear to those skilled in the art, after reading this specification, how to make and use alternative embodiments of the present invention that comprise splitters of any fan out. It will be clear to those skilled in the art how to make and use splitter  305 - i.    
         [0044]      FIG. 4  depicts a block diagram of the salient components of power system  203 . Power system  203  comprises power supply  401 - 1  and  401 - 2 , interrelated as shown. In some alternative embodiments of the present invention, any number of power supplies can be used.  
         [0045]     Power supply  401 - i  comprises output terminals  402 - i - 1  through  402 - i - 4 . Although the power supplies in the illustrative embodiment each have four output terminals, it will be clear to those skilled in the art, after reading this specification, how to make and use alternative embodiments of the present invention that comprise power supplies with any number of output terminals.  
         [0046]     Power supply  401 - i  uses the control signals received from launch control system  201  on bus  205  to determine to which output terminal should power be supplied (i.e., should be energized). Power supply  401 - i  is capable of energizing one or more of output terminals  402 - i - 1  through  402 - i - j . Furthermore, power supply  401 - i  is capable of energizing output terminals  402 - i - 1  through  402 - i - j  independently of each other. It will be clear to those skilled in the art, after reading this specification, how to make and use power supply  401 - i.    
         [0047]      FIG. 5  depicts Missile Bank  204 , in accordance with the illustrative embodiment of the present invention. Missile Bank  204  comprises eight (8) missiles  102 - 1 - 1  through  102 - 2 - 4 .  
         [0048]     As can be seen in  FIG. 5 , the hot-start navigational information arriving from splitter  305 - 1  is received by missiles  102 - 1 - 1  through  102 - 1 - j . Similarly, the distributed hot-start navigational information arriving from splitter  305 - 2  is received by missiles  102 - 2 - 1  through  102 - 2 - j . Furthermore, the energizing signal associated with output terminal  402 - i - j  of power supply  401 - i  powers missile  102 - i - j.    
         [0049]      FIG. 6  depicts a block diagram of the salient components of missile  102 - i - j , in accordance with the illustrative embodiment of the present invention.  
         [0050]     Missile  102 - i - j  comprises Global-Positioning-System receiver  601 - i - j , as is well-known in the art, to monitor and control its flight path to an intended target Global-Positioning-System receiver  601 - i - j  receives the hot-start navigational information from splitter  305 - i.    
         [0051]     Receiver  601 - i - j  is specifically “addressed” by launch control system  201  when it is energized by power supply  401 - i  through output terminal  402 - i - j . Once receiver  601 - i - j  is “addressed,” it accepts—in contrast to merely receives—the hot-start navigational information from splitter  305 - i . In fact, only if receiver  601 - i - j  is energized does it accept the hot-start navigational information from processor  301 .  
         [0052]     Receiver  601 - i - j  also receives a signal in well-known fashion from one or more of the satellites in satellite constellation  104 . Once receiver  601 - i - j  accepts the hot-start navigational information, it reads in, as part of the hot-start navigational information from Global-Positioning-System Integrator  202 , (i) the characteristic from a Global-Positioning-System satellite and (ii) the black cryptographic key comprising the red cryptographic key. Receiver  601 - i - j  decrypts the red cryptographic key from the black cryptographic key in well-known fashion. Receiver  601 - i - j  then uses the characteristic and red cryptographic key to acquire one or more Global-Positioning-System satellites, and subsequently to determine its position.  
         [0053]     It will be clear to those skilled in the art, after reading this disclosure, how to make and use receiver  601 - i - j.    
         [0054]      FIG. 7  depicts a flowchart of the salient tasks performed by weapons control system  200  in accordance with the illustrative embodiment of the present invention. It will be clear to those skilled in the art which tasks depicted in  FIG. 7  can be performed simultaneously or in a different order than that depicted.  
         [0055]     At task  701 , weapons control system  200  selects a missile (and its associated Global-Positioning-System receiver) to receive and accept the hot-start navigational information from processor  301 . To accomplish this, system  200  (i) selects the transmitter (of transmitters  304 - 1  and  304 - 2 ) associated with the missile and (ii) selects the power supply (of power supplies  401 - 1  and  401 - 2 ) and the terminal (of terminals  401 - i - j ) associated with the selected missile. It will be clear to those skilled in the art, after reading this specification, how to perform task  701 .  
         [0056]     At task  702 , weapons control system  200  generates the hot-start navigational information and transmits the hot-start navigational information through selected the transmitter(s). For example, if the selected missile is missile  201 - 2 - 1  (and, therefore, the associated Global-Positioning-System receiver receiver  601 - 2 - 1 ), then processor  301  transmits the generated hot-start navigational information to through transmitter  304 - 2 . Task  702  is described in detail below and with respect to  FIG. 8 .  
         [0057]     At task  703 , weapons control system  200  directs the selected power supply to energize the output associated with the selected missile. For example, if the selected missile is missile  201 - 2 - 1 , then weapons control system  200  directs power supply  401 - 2  to energize output terminal  402 - 2 - 1 . The effect of energizing output terminal  402 - 2 - 1  is that that receiver  601 - 2 - 1  (within missile  102 - i - j ) is powered and consequently can accept the hot-start navigational information on optical fiber  307 - 2 - 1 . It will be clear to those skilled in the art how to perform task  703 .  
         [0058]      FIG. 8  depicts a flowchart of the salient subtasks associated with task  702 , in accordance with the illustrative embodiment of the present invention. It will be clear to those skilled in the art which tasks depicted in  FIG. 8  can be performed simultaneously or in a different order than that depicted.  
         [0059]     At subtask  801 , Global-Positioning-System Integrator  202  receives a black cryptographic key from which a red cryptographic key is derivable. Global-Positioning-System Integrator  202  also receives a signal from a Global-Positioning-System satellite in satellite constellation  104 .  
         [0060]     At subtask  802 , Global-Positioning-System Integrator  202  derives a characteristic of the signal by using the red cryptographic key.  
         [0061]     At subtask  803 , Global-Positioning-System Integrator  202  transmits, via transmitter  304 - i  and splitter  305 - i , (i) the characteristic of the signal and (ii) the black cryptographic key to Global-Positioning-System receiver  601 - i - j.    
         [0062]     It is to be understood that the above-described embodiments are merely illustrative of the present invention and that many variations of the above-described embodiments can be devised by those skilled in the art without departing from the scope of the invention. For example, in this Specification, numerous specific details are provided in order to provide a thorough description and understanding of the illustrative embodiments of the present invention. Those skilled in the art will recognize, however, that the invention can be practiced without one or more of those details, or with other methods, materials, components, etc.  
         [0063]     Furthermore, in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the illustrative embodiments. It is understood that the various embodiments shown in the Figures are illustrative, and are not necessarily drawn to scale. Reference throughout the specification to “one embodiment” or “an embodiment” or “some embodiments” means that a particular feature, structure, material, or characteristic described in connection with the embodiment(s) is included in at least one embodiment of the present invention, but not necessarily all embodiments. Consequently, the appearances of the phrase “in one embodiment,” “in an embodiment,” or “in some embodiments” in various places throughout the Specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments. It is therefore intended that such variations be included within the scope of the following claims and their equivalents.