Abstract:
A field unit and ground station may use commercial off-the-shelf (COTS) components and share a common architecture, where differences in functionality are governed by software. The field units and ground stations may be easy to deploy, relatively inexpensive, and be relatively easy to operate. A novel file system may be used where datagrams of a file may be stored across multiple drives and/or devices. The datagrams may be received out of order and reassembled at the receiving device.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. provisional patent application No. 62/016,564 filed on Jun. 24, 2014. The subject matter of this earlier filed application is hereby incorporated by reference in its entirety. 
     
    
     STATEMENT OF FEDERAL RIGHTS 
       [0002]    The United States government has rights in this invention pursuant to Contract No. DE-AC52-06NA25396 between the United States Department of Energy and Los Alamos National Security, LLC for the operation of Los Alamos National Laboratory. 
     
    
     FIELD 
       [0003]    The present invention generally relates to space vehicles, and more particularly, to a relatively low cost, highly reliable field unit and ground station for a space vehicle that share common components. 
       BACKGROUND 
       [0004]    In conventional field units and ground stations, different system components, designed by a variety of manufacturers, are integrated and used for the field unit and ground station. Also, different software is used for these systems. This adds cost and complexity while reducing reliability. Accordingly, a more cost-effective and reliable field unit and ground station system may be beneficial. 
       SUMMARY 
       [0005]    Certain embodiments of the present invention may provide solutions to the problems and needs in the art that have not yet been fully identified, appreciated, or solved by conventional field unit and ground station systems. For example, some embodiments pertain to a field unit and ground station that use commercial off-the-shelf (COTS) components and share a common architecture, where differences in functionality are governed by software. In certain embodiments, a novel file system is used where frames of a file may be stored across multiple drives and/or devices. The frames may be received out of order and reassembled at the receiving device. 
         [0006]    In an embodiment, an apparatus includes at least one hardware board configured to enable operation of the apparatus as a field unit and a ground station. Software controls whether the apparatus operates as a field unit or a ground station without physical modification to the at least one hardware board. 
         [0007]    In another embodiment, a field unit/ground station (FU/GS) box includes an analog radio board configured to send and receive radio signals via an antenna. The FU/GS box also includes a digital radio board configured to interface with the analog radio board and provide digital radio functionality. The FU/GS box further includes a microcontroller board configured to provide processing for the FU/GS box and a backplane that connects the analog radio board, digital radio board, and microcontroller board, facilitating communication between the boards. Software controls whether the FU/GS box operates as a field unit or a ground station without physical modification to the boards. 
         [0008]    In yet another embodiment, a system includes at least one field unit and at least one ground station. The at least one field unit and the at least one ground station have common hardware. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    In order that the advantages of certain embodiments of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. While it should be understood that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which: 
           [0010]      FIG. 1  is a perspective view illustrating a deployed space vehicle system, according to an embodiment of the present invention. 
           [0011]      FIGS. 2A and 2B  are architectural diagrams illustrating a ground station, according to an embodiment of the present invention. 
           [0012]      FIG. 3  is a block diagram illustrating an RF box, according to an embodiment of the present invention. 
           [0013]      FIG. 4  is a photograph illustrating a prototype RF box, according to an embodiment of the present invention. 
           [0014]      FIG. 5  is a block diagram illustrating a lightning box, according to an embodiment of the present invention. 
           [0015]      FIG. 6  is a photograph illustrating a prototype lightning box, according to an embodiment of the present invention. 
           [0016]      FIG. 7  is a block diagram illustrating a ground station (GS) box, according to an embodiment of the present invention. 
           [0017]      FIG. 8  is a photograph illustrating a prototype GS box, according to an embodiment of the present invention. 
           [0018]      FIG. 9  is a photograph illustrating a prototype ground station antenna assembly, according to an embodiment of the present invention. 
           [0019]      FIG. 10  is a perspective view illustrating the inside of a ground station/field unit box, according to an embodiment of the present invention. 
           [0020]      FIG. 11  is a perspective view illustrating a ground station/field unit box, according to an embodiment of the present invention. 
           [0021]      FIG. 12  is an architectural diagram illustrating a field unit system, according to an embodiment of the present invention. 
           [0022]      FIG. 13  is a perspective view illustrating a field unit box, according to an embodiment of the present invention. 
           [0023]      FIG. 14A  is a photograph illustrating a closed field unit box, according to an embodiment of the present invention. 
           [0024]      FIG. 14B  is a photograph illustrating the field unit box with an open case, according to an embodiment of the present invention. 
           [0025]      FIG. 14C  is a photograph illustrating stacked boards of the field unit box, according to an embodiment of the present invention. 
           [0026]      FIG. 15  is a screenshot illustrating ground station control software, according to an embodiment of the present invention. 
           [0027]      FIG. 16  is a screenshot illustrating simplified ground station control software, according to an embodiment of the present invention. 
           [0028]      FIG. 17  is a block diagram illustrating connection setup for a ground station, space vehicle, and field unit system, according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0029]    Some embodiments of the present invention pertain to a relatively low cost field unit and ground station system that use the same boards and reuse the majority of the software. The field unit and ground station may use commercial off the shelf (COTS) components and have a relatively simple software interface. The system may be highly reliable, operating for extended periods of time. The system may also be highly optimized for a wide variety of missions to improve performance and lower costs. In other words, the field unit and ground station may be readily adaptable to a wide range of missions “out of the box,” and the principal hardware may be fully commoditized. The ground station may be a fully Internet-capable control station that can facilitate user-defined, user-controlled custom space solutions. In certain embodiments, the user community may have full control of the system via software, hardware, ease of use, and wide adoption. 
         [0030]      FIG. 1  is a perspective view illustrating a deployed space vehicle system  100 , according to an embodiment of the present invention. System  100  includes a ground station  110 , a space vehicle  120 , and a field unit  130 . In some embodiments, there may be multiple ground stations, multiple field units, multiple space vehicles, or any combination thereof. Furthermore, in some embodiments, space vehicles may communicate with one another and/or be individually customized to perform different missions or to have different capabilities in order to create a space vehicle “swarm” that has more capabilities than any individual space vehicle. 
         [0031]    Ground station  110  provides command and control capabilities for space vehicle  120  using two-way communication and for field unit  130  using the satellite as a relay. Space vehicle  120  may collect data in accordance with its mission and transmit the data to ground station  110 . In some embodiments, field unit  130  collects data, space vehicle  120  collects the data from field unit  130 , and space vehicle  120  relays the data to ground station  110 . In certain embodiments, ground station  110  transfers data to space vehicle  120 , and space vehicle  120  transfers the data to field unit  130  at a later time. In some embodiments, ground station  110  communicates with field unit  130  in real time or near-real time, using space vehicle  120  as a relay. 
       Ground Station and Field Unit 
       [0032]      FIGS. 2A and 2B  are architectural diagrams illustrating a ground station  200 , according to an embodiment of the present invention. An antenna  210  is configured to facilitate two-way communication with space vehicles. Antenna  210  includes downlink antennas  212  and uplink antennas  214 . Downlink antennas  212  and uplink antennas  214  each operate at a frequency of 915 megahertz (MHz) with a gain of 14 decibels-isotropic (dBi). Using two downlink antennas  212  and uplink antennas  214  enables circular polarization. Combiners and custom brackets  216  fasten downlink antennas  212  and uplink antennas  214  to antenna  210 . 
         [0033]    A rotor  220  moves antenna  210  to facilitate better reception. An RF box  222  allows long cable runs and sends signals to and receives signals from antenna  210 . A mast  224  holds antenna  210 , rotor  220 , and RF box  222  in an upright position. Transmitting (TX) and receiving (RX) cables and rotor azimuth (AZ) and elevation (EL) cables run between, and connect, rotor  220  and RF box  222 . 
         [0034]    A lightning box  230  is connected to RF box  222  via antenna TX and RX cables and rotor AZ and EL cables. Lightning box  230  is grounded and protects other connected electronics from current surges due to lightning strikes. Lightning box  230  is also connected to a ground station (GS) box  240  via antenna TX and RX cables and rotor AZ and EL cables. In some embodiments, these cables may be hundreds of feet long or more. 
         [0035]    GS box  240  may be rugged, relatively easy to use, and be run from a standard personal computer, tablet computer, mobile phone, or any other suitable computing device, such as laptop  250 . Antenna  210 , rotor  220 , RF box  222 , mast  224 , lightning box  230 , and GS box  240  may be compact and portable, allowing deployment in many locations. In certain embodiments, multiple computing systems may be used to control ground station  200 . 
         [0036]    GS box  240 , which is controlled by laptop  250 , controls the orientation of antenna  210  via rotor control box  242  and sends data to/receives data from the space vehicle via transceiver box  244 . GS box  240  also contains sensitive electronics and cryptographic keys for communication. In some embodiments, GS box  240  may be attached to antenna  210  or integrated with rotor  220  itself. In such embodiments, laptop  250 , or any other suitable computing device, may communicate remotely with GS box  240 . In such embodiments, a user may potentially control the operation of ground station  200  from any desired location. Laptop computer  250  communicates with GS box  240  to send communication data to space vehicles, receive digital space vehicle communication data, and control the orientation of antenna  210  via rotor  220 . 
         [0037]      FIG. 3  is a block diagram illustrating an RF box  300 , according to an embodiment of the present invention. RF box  300  includes a transmit and receive chain to provide amplification in order to enable long cable runs between the ground station box and the antennas, and is placed near the antennas. RF box  300  may be powered by AC wall power to simplify setup. The transmit chain includes a power amplifier (PA)  305 , an isolator  310 , a filter  315 , and appropriate RF cable connectors (N-connectors  320 ), using an AC/DC power converter  325  to power PA  305 . The receive chain includes a filter  330 , a low noise amplifier (LNA)  335 , and appropriate RF cable connectors (N-connectors  340 ), using an AC/DC power converter  345  to power LNA  335 . 
         [0038]      FIG. 4  is a photograph illustrating a prototype RF box  400 , according to an embodiment of the present invention. In RF box  400 , the filters, LNA, and PA are visible. RF box  400  has a rugged, weatherproof, fully enclosed outdoor case that houses the sensitive electronics inside. 
         [0039]      FIG. 5  is a block diagram illustrating a lightning box  500 , according to an embodiment of the present invention. Lightning box  500  provides protection for the RF transmit and receive signal paths and the rotor control signal paths. For RF protection, a standard RF lightning protector may be used. For rotor control protection, separate AC and DC paths may be provided to accommodate both types of signals using standard AC and DC lightning protection approaches. 
         [0040]      FIG. 6  is a photograph illustrating a prototype lightning box  600 , according to an embodiment of the present invention. Lightning box  600  has a rugged case that houses internal electronics. 
         [0041]      FIG. 7  is a block diagram illustrating a GS box  700 , according to an embodiment of the present invention. GS box  700  houses the satellite radio and antenna rotor controllers. The rotor controller may be accessed by connecting GS box  700  to a computer using a USB cable. A USB-to-RS-232 converter may be used to interface to the rotor controller. Custom bayonet/screw-on connectors may be provided on the outside of GS box  700  to enable ground station setup without requiring tools. The controller may be powered by standard AC wall power. The satellite radio transceiver may be accessed by connecting GS box  700  to a computer using a USB cable, and may be powered by a standard AC/DC converter. The radio of GS box  700  may be identical to the radio used on the space vehicle. Standard RF coaxial connectors may be provided for the transmit and receive signal paths, enabling ground station setup without requiring tools. 
         [0042]      FIG. 8  is a photograph illustrating a prototype GS box  800 , according to an embodiment of the present invention. GS box  800  has a rugged case that houses sensitive internal electronics. GS box  800  enables control of antenna orientation and facilitates communication with space vehicles via the antenna. 
         [0043]      FIG. 9  is a photograph illustrating a prototype ground station antenna assembly  900 , according to an embodiment of the present invention. In antenna assembly  900 , separate antennas are used for transmission and reception, and antenna pairs are used for each to enable circular polarization. As can be seen, antenna assembly  900  is relatively compact, enabling deployment in a large variety of operating environments. The RF box is visible next to the antenna. 
         [0044]    An advantage of some embodiments is that they can be built using COTS parts, including the rotor, antennas, ground station box boards, controlling computer, etc. The system may only cost a few thousand dollars in some embodiments. The system may also be deployable in non-pristine environments. In a poor conditions test in a snowy environment, the prototype system performed normally. 
         [0045]      FIG. 10  is a perspective view illustrating the inside of a ground station/field unit (GS/FU) box  1000 , according to an embodiment of the present invention. GS/FU box  1000  includes an analog radio board  1010  that sends and receives radio signals via an antenna (not shown). A digital radio board  1020  interfaces with analog radio board  1010  and provides digital radio functionality. GS/FU box  1000  achieves higher data rates than other satellite communication systems relative to the size and power consumption. A microcontroller board  1030 , such as a Linux™ single board computer (SBC), e.g., Beagleboard™, provides processing for GS/FU box  1000 . A backplane  1040  connects the boards, facilitating communication therebetween, and also connects to a power supply (not shown). In some embodiments, the dimensions are approximately 4×4×2 inches. In certain embodiments, all functionality may be achieved with, and performed by, a single board. 
         [0046]    Some embodiments may have various ports, such as universal serial bus (USB), Ethernet, power ports, an external antenna connector, etc. In certain embodiments, the ports of GS/FU box  1000  may be exposed. In such embodiments, a protective enclosure that shields GS/FU box  1000  from the elements should be used. The protective enclosure may include a casing protecting GS/FU box  1000  from weather, vents, cooling fans, etc. 
         [0047]      FIG. 11  is a perspective view illustrating a GS/FU box  1100 , according to an embodiment of the present invention. GS/FU box  1100  includes a CATS port  1110 , a USB port  1120 , a general purpose input/output (GPIO) port  1130 , and an N-connector port  1140  for receiving a radio frequency (RF) signal. A light emitting diode (LED) power indicator  1150  indicates whether GS/FU box  1100  is on and has power. 
         [0048]    Per the above, a common box may be used for deployment in a ground station or a field unit in some embodiments. In certain embodiments, the logic enabling ground station functionality, field unit functionality, or both may be stored on a storage device, such as a secure digital (SD) card, a flash drive, or any other storage device that may be plugged into the GS/FU box, which may then read and executes the code. In some embodiments, code containing the logic may be downloaded by the GS/FU box via a wired or wireless connection. Encryption keys may also be stored on the storage device or downloaded from a remote computing system. This may enable certain security privileges on a per-user basis (e.g., administrator, user, etc.). 
         [0049]      FIG. 12  is an architectural diagram illustrating a field unit system  1200 , according to an embodiment of the present invention. A direct current (DC) power supply  1210  provides power to a field unit box  1220 . In some embodiments, alternating current (AC) power may be used instead of DC power. Field unit box  1220  communicates with one or more space vehicles via an antenna  1230 . In some embodiments, field unit  1220  may only receive data from space vehicles and may not transmit data, or may lack transmission capabilities. A sensor  1240  is connected to field unit box  1220 . In this embodiment, field unit box  1220  serves as a modem to relay data taken by sensor  1240  back to a ground station, or to allow the ground station to command sensor  1240 . 
         [0050]    In some embodiments, deployment of field unit system  1200  may be relatively easy and not require special expertise. For instance, in some embodiments, a user may plug sensor  1240  into field unit box  1220 , plug antenna  1230  into field unit box  1220 , position antenna  1230 , plug DC power supply  1210  into field unit box  1220 , and walk away. This ease of deployment is not possible with conventional field unit systems. 
         [0051]      FIG. 13  is a perspective view illustrating a field unit box  1300 , according to an embodiment of the present invention. Field unit box  1300  includes a patch antenna  1310  that enables field unit  1300  to uplink data from external sources, such as data detected by sensors attached to RJ45 Ethernet interface  1320 , to a space vehicle. Communications may use any desired authentication and encryption format, such as NSA Suite B. Field unit  1300  also includes a USB interface  1330 , an RGB LED  1340  that indicates field unit status, and a power jack  1350 , which may have a wide power supply range. Field unit  1300  may share at least some common hardware and software with a space vehicle and ground station in some embodiments. 
         [0052]      FIGS. 14A-C  illustrate a closed and opened prototype field unit box  1400  and boards  1410  stacked within field unit box  1400 , according to an embodiment of the present invention. Field unit box  1400  is compact and easily accessible once the case is opened. 
       Software 
       [0053]    In some embodiments, orbit tracking software may provide tracking, rotor control, Doppler calculation, etc. A script may be provided for automatic two-line element (TLE) updates. The user interface may be relatively simple, with a graphical representation of space vehicle locations and ranges on a map. The user interface may also display satellite communications and provide logging. Conventional ground station software is complex and requires extensively trained, specialized users to operate. Moreover, conventional ground stations typically require an operator to be present, i.e., they do not support unattended operations. By contrast, some embodiments present a simple user interface, enabling non-expert users to task and operate the satellite quickly, and enable fully automated “lights-out” space vehicle operations, vastly lowering the cost and infrastructure required to operate the space vehicle system. 
         [0054]      FIG. 15  is a screenshot  1300  illustrating ground station control software, according to an embodiment of the present invention. The ground station control software includes a map  1510  that displays satellite positions relative to the Earth and ground footprints. A satellite selection panel  1520  allows a user to view data for various satellites, such as azimuth, elevation, range, height, etc. Selection panel  1520  also allows the user to select a satellite to control. 
         [0055]    An azumith/elevation panel  1530  shows the azimuth and elevation for the selected satellite. A radio control panel  1540  shows the frequency at the satellite, Doppler shift, and transmit frequency for uplink and downlink. The uplink transmit frequency and downlink frequency at the satellite can also be controlled. A command interface  1550  allows the user to enter commands and also shows log data. In certain embodiments, all of the panels may be integrated into a single window. The control software may allow full control over the satellite and provide a large amount of diagnostic information. Simplified ground station software is illustrated in screenshot  1600  of  FIG. 16 . 
         [0056]    Per the above, the field unit may not provide the user with the ability to control space vehicles or to communicate with space vehicles at all. The field unit may steam data to a computing system associated with the field unit and display the data in a graphical user interface (GUI). For example, the field unit software may enable the user to get certain data transmitted by the space vehicle, such as photos, video, audio, etc. 
         [0057]      FIG. 17  is a block diagram  1700  illustrating connection setup for a ground station, space vehicle, and field unit system, according to an embodiment of the present invention. In this embodiment, ground station  1710  initiates a connection with space vehicle  1720 . Space vehicle  1720  then initiates a connection with field unit  1730 . Field unit  1730  cannot initiate connections in this embodiment. Proof of identity, key exchange, data encryption, and other security may be performed using known techniques (e.g., digital signature algorithm (DSA), station-to-station (STS) protocol, etc.). 
         [0058]    Conventional space vehicle systems use FAT file systems or similar formats, using Internet Protocol (IP) or similar protocols for file transfer. In these systems, files are stored sequentially, and are similarly transferred sequentially. Specifically, for file transfer, the file is split into a set of datagrams that are assigned a sequence number and again transferred sequentially, using a retry protocol to re-send corrupted datagrams. This type of transfer protocol assumes a single sender and receiver (destination). A major disadvantage of this type of system is that it does not allow for files to be transmitted piecemeal, using multiple satellites to transfer different portions of the file. 
         [0059]    To address this and other issues, some embodiments combine a number of different features of various file systems and transfer protocols to create a new, unique approach. Files may be split into datagrams as before, but a metadata header may be attached that contains the origin of the file, the file name, the sequence number, and other information to enable data transfer. These datagrams may be wholly self-contained, and may be transferred and stored individually on an ad-hoc basis. The sender may track which datagrams were successfully transferred, using an ack/retry protocol, without knowledge of the final destination. Intermediate nodes may then be used to store and eventually re-transmit this data as many times as needed until the data is finally gathered together and reassembled at the destination. The resulting system is a combination of a distributed file system and a transfer protocol that is uniquely suited to constellations of small satellites. 
         [0060]    An advantage of this approach is that files can be transferred out of order and reassembled. Also, multiple space vehicles may transmit or receive different portions of a file. For instance, a first space vehicle may get a frame of an uplink file. Later, a second satellite may get several more frames, etc. This also works in the reverse direction with respect to the GS/FU. A satellite may transfer some fraction of frames to the first ground station it encounters, transfer more data to a second ground station, and so on. The file may become more and more fractionated, but all data is still present to eventually re-assemble the file at a final receiving node, without the ultimate sending and receiving nodes ever directly communicating with one another. 
         [0061]    It will be readily understood that the components of various embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the detailed description of the embodiments of the present invention, as represented in the attached figures, is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. 
         [0062]    The features, structures, or characteristics of the invention described throughout this specification may be combined in any suitable manner in one or more embodiments. For example, reference throughout this specification to “certain embodiments,” “some embodiments,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in certain embodiments,” “in some embodiment,” “in other embodiments,” or similar language throughout this specification do not necessarily all refer to the same group of embodiments and the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
         [0063]    It should be noted that reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, discussion of the features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment. 
         [0064]    Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention. 
         [0065]    One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims.