Abstract:
The present invention is a stackable telemetry circuit board for use in telemetry systems for satellites and other purposes. The present invention incorporates previously-qualified interchangeable circuit boards, or “decks,” that perform functions such as power, signal receiving and transmission, and processing. Each deck is adapted to serve a range of telemetry applications. This provides flexibility in the construction of the stackable telemetry circuit board and significantly reduces the cost and time necessary to develop a telemetry system.

Description:
FEDERAL RESEARCH STATEMENT 
     The invention described herein was made by employees of the United States Government and may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefore. 
    
    
     FIELD OF INVENTION 
     The present invention relates to the field of satellite telemetry systems, and more specifically to a modularly designed transponder device that can be rapidly configured for use with any telemetry system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an isometric view of exemplary embodiment of a stackable telemetry circuit board apparatus. 
         FIG. 2  illustrates an exemplary embodiment of a receiver deck for a stackable telemetry circuit board. 
         FIG. 3  is an exemplary embodiment of a processor deck for stackable telemetry circuit board. 
         FIG. 4  is an exemplary embodiment of a transmitter deck for a stackable telemetry circuit board. 
         FIG. 5  is an exemplary embodiment of a power supply deck for a stackable telemetry circuit board. 
         FIG. 6  is an exemplary embodiment of satellite that uses a stackable telemetry circuit board. 
     
    
    
     BACKGROUND 
     Telemetry refers to the technology used by remote sources such as space vehicles to measure and transmit data to ground-based receiving stations, and vice versa. Within a telemetry system, the transponder is a critical device which picks up and automatically responds to an incoming signal. A transponder contains the processing capability, including error checking functions, to ensure the reliability of the data. 
     With the associated hardware necessary for a satellite to interface with the transponder, a typical NASA telemetry system costs $5 to $10 million dollars per satellite. 
     A primary cost associated with development and customization of transponders and telemetry systems is the configuration and development of error checking components. Specific error checking protocols are required for various telemetry applications. Error checking is a “modular function,” that is carried out independently of other processing activities. 
     All error checking protocols must comply with Ground Network and Consultative Committee for Space Data System (CCSDS) protocols which are required for each telemetry application. 
     Because both error checking functions and CCSDS protocols are modular, hardware and software for error checking theoretically may be inserted or removed from the data stream telemetry requirements. 
     Examples of current telemetry system error checking protocols include Reed Solomon (forward error correction), BCH (error detection only), Pseudo-Randomization (required for operation), turbo codes, convolutional code (1/2, 7/8), Virterbi, auto-ranging, encryption, and cyclic redundancy check (CRC). 
     An additional problem known in the art is the need for strict quality control protocols or “prequalification” of each component used by NASA. The qualification process is extremely costly and generally requires that a new device be tested in a NASA lab or have been previously used in flight. Components meeting this standard are referred to, in the art, as “prequalified” devices. 
     The qualification process limits the availability of transponders designed to interface with rapidly evolving and diverse telemetry systems including lunar missions and missions to Mars, military intelligence, wireless internet, cellular telephones, climate change studies, and emergency services such as fire, ambulance and police. 
     SUMMARY OF THE INVENTION 
     The present invention is a novel, modularly constructed telemetry transponder apparatus and system comprised of discrete and interchangeable decks which house telemetry components. The various interchangeable decks are comprised entirely of prequalified components, allowing a functional transponder to be specifically configured for a range of telemetry systems on a time-sensitive and low-cost basis. 
     In various embodiments the transponder may include modularly interchangeable telemetry receiver decks, transmitter decks, processor decks and power supply decks configured to be compatible with various telemetry systems. In particular, various embodiments will utilize interchangeable processing decks with specific FEC protocols needed for fully compatible upload and download capability for a wide range systems. 
     Terms of Art 
     As used herein, the term “Command and Data Handling” or “C&amp;DH” means a system that receives and executes commands; collects, stores, and transmits house-keeping data; and supports the onboard payloads. 
     As used herein, the term “Costas loop” means a software configuration implemented on a hardware processing component that is a phase-locked loop which is used for carrier phase recovery from suppressed-carrier modulation signals. 
     As used herein, the term “deck” refers to a structure for mounting a circuit board and integrated components, which further may allow one or more circuit boards and associate components to be operatively coupled, thus integrating functionality. A deck may house components which relate to a specific functionality, and may further be used to physically position processing components so that they can be physically replaced or interchanged without requiring an entirely new processor to be configured. In particular, a deck may be used to house multiple prequalified parts, and the deck may be qualified in its entirety. 
     As used herein, the term “down converter” means a circuit which converts a signal that is received at one frequency to another frequency. 
     As used herein, the term “downlink component” refers to any components, including but not limited to filters, synchronizers, error-checking processing components, general packet processing components, or any other components that or facilitate the communication from flight computer (e.g., a satellite) to a ground computer. 
     As used herein, the term “EMI filter” refers to an electromagnetic interference filter which filters disturbances that affect electrical circuits due to either electromagnetic induction or electromagnetic radiation. 
     As used herein, the term “error checking” protocol means any error checking protocol that is compliant with CCDS or equivalent standards. Example of error checking protocols include, but are not limited to Reed Solomon (forward error correction), BCH (error detection only), Pseudo-Randomization (required for operation), turbo codes, convolutional code (rates ½ and ⅞), Virterbi, auto-ranging, encryption, and cyclic redundancy check (CRC). 
     As used herein, the term “Field-Programmable Gate Array” or “FPGA” means an integrated circuit that can be programmed after manufacturing to perform the functions of an application specific integrated circuit (ASIC). 
     As used herein, the term “Forward Error Correcting protocol” or “FEC” means a system of error control for data transmission wherein the sending system adds systematically-generated redundant data to its messages. This allows the receiver to detect and correct errors in the transmission without having to request the retransmission of data. 
     As used herein, the term “local oscillator” or “LO” means an electronic device used to generate a signal for the purpose of converting a signal to a different frequency. 
     As used herein, the term “Low Density Parity Check” or “LDPC” means a linear error correction code used for transmitting messages that can withstand noisy transmission signals. 
     As used herein, the term “Low Noise Amplifier” or “LNA” means an electronic amplifier that is used to amplify very weak signals. 
     As used herein, the term “Low Pass Filter” or “LPF” means an electronic filter that passes low-frequency signals but reduces the amplitude of signals with frequencies higher than the cutoff frequency. 
     As used herein, the term “modularly configured” referrers to a component adapted to be utilized with minimal configuration or replacement of component parts as opposed to replacement of an entire system. 
     As used herein, the term “phase lock loop” or “PLL” means a control system which generates an output signal that uses a negative phase feedback technique for extracting a coherent frequency relative to an input signal. 
     As used herein, the term “prequalified system” means a system, deck, circuit board or component which conforms to a prequalification process. For example, a deck or a component on a deck may be prequalified. 
     As used herein the term “radio frequency (RF) to baseband analog mixer” means a device that creates a new radio frequency signal from two or more incoming signals from two different radio frequencies. 
     As used herein, the term “radio frequency (RF) baseband filter” means a device that performs the signal processing function of removing radio frequencies outside of a specified range for the purposes of enhancing the quality of desired radio frequencies. 
     As used herein the term “radio frequency (RF) to baseband analog mixer” means a device that creates a new radio frequency signal from two or more incoming signals from two different radio frequencies. 
     As used herein, the term “receiver” means hardware configured for receiving telemetry data transmissions. 
     As used herein, the term “S-band carrier” means a carrier of radio frequencies between 2 and 4 GHz. 
     As used herein, the term “up-convert” means to convert a lower frequency signal to a higher frequency. 
     As used herein, the term “uplink components” refers to filters, synchronizers, error-checking processing components, general packet processing components, or any processing components that can interface from a ground computer to a flight computer. 
     As used herein, the term “X-band” means a segment of the microwave radio region of the electromagnetic spectrum ranging from 8-10 GHz. 
     DETAILED DESCRIPTION OF INVENTION 
     For the purpose of promoting an understanding of the present invention, references are made in the text to exemplary embodiments of a telemetry system which utilizes interchangeable prequalified decks and associated components, only some of which are described herein. It should be understood that no limitations on the scope of the invention are intended by describing these exemplary embodiments. One of ordinary skill in the art will readily appreciate that alternate but functionally equivalent components, materials, and placement may be used. The inclusion of additional elements may be deemed readily apparent and obvious to one of ordinary skill in the art. Specific elements disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one of ordinary skill in the art to employ the present invention. 
     It should be understood that the drawings are not necessarily to scale; instead, emphasis has been placed upon illustrating the principles of the invention. In addition, in the embodiments depicted herein, reference numerals in the various drawings refer to identical or near identical structural elements. 
     Moreover, the terms “substantially” or “approximately” as used herein may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. 
       FIG. 1  illustrates an exemplary embodiment of stackable telemetry circuit board  100  comprised of a plurality of interchangeable decks. A “deck” is a structure or housing for mounting a circuit board and integrated components, which may allow for one or more circuit boards and associated components to be operatively coupled, thus integrating functionality. More specifically, a deck may be used to house multiple prequalified parts, or the deck itself may be qualified in its entirety. In the embodiment shown, each deck may house components which relate to a specific functionality, and may further be used to physically position processing components so that they can be physically replaced or interchanged without requiring an entirely new processor to be configured. 
     In the embodiment shown, stackable telemetry circuit board  100  includes receiver deck  15 , processor deck  25 , transmitter deck  35 , and power supply deck  45  which each perform their respective function. Decks  15 ,  25 ,  35  and  45  are arranged and operatively coupled in a vertically stacked configuration. Other embodiments may include more or fewer decks, and in still other embodiments decks may be constructed to be operationally coupled in a non-vertical or other physical configuration. 
     In the embodiment shown, receiver deck  15  is modularly configured to receive data signals from a ground station transmitter. Processor deck  25  is modularly configured to convert the signal based on command and data handling. In the embodiment shown, transmitter deck  35  is modularly configured to transmit a signal and power supply deck  45  provides power and is modularly configured to regulate, control, and supply different power levels to the different decks. 
       FIG. 2  illustrates an exemplary embodiment of receiver deck  15  for stackable telemetry circuit board  100  (shown in  FIG. 1 ). In the embodiment shown, receiver deck  15  is modularly configured to receive a signal from a ground transmitter and is comprised of circuit board  10  with critical components receiver (RCVR)  11 , down convert and low pass filter (LPF)  12 , Costas loop (or analog-to-digital converter)  13 , and local oscillator  14 . In the embodiment shown, receiver  11  may operate at levels down to −115 dBm at 2-2.4 GHz and less than 1 decibel of Noise Figure (NE). 
     In various embodiments, receiver deck  15  may also include a phase lock loop (PLL), a low noise amplifier, an RF to baseband analog mixer or an RF baseband filter or any combination thereof. 
       FIG. 3  is an exemplary embodiment of processor deck or ARM-forward error correction and field programmable gate array (FPGA) deck  25 . In the embodiment shown, processor deck  25  is comprised of circuit board  20  with critical components digital signal processor (DSP)  21 , bit sync data recovery component  22 , data formatting component  23  and low density parity check (LDPC)  24 . In other embodiments, an application specific integrated circuit (ASIC) may be used to perform Reed Solomon forward error correction. In other embodiments, processor deck  25  may include at least one FPGA configured with BCH (error detection) or Pseudo-Randomization protocols. The FPGA may also perform telemetry uplink and telemetry downlink processes. In these embodiments, the FPGA may include uplink components such as filters, synchronizers, error checking components, general packet processing components or an interface to flight computer. In other embodiments, uplink component may be hardware, software or firmware. In the embodiment shown, uplink operates at 2073.38 MHz. In various other embodiment, uplink may be reconfigured during use to operate at a different frequency throughout the S-band (2-2.4 GHz) range. 
     Further, in other embodiments, the FPGA may also include a downlink component such as an interface to a flight computer, forward error correction or additional packet processing software components such as encryption. Likewise, the downlink component may be hardware, software or firmware. 
       FIG. 4  is exemplary embodiment of transmitter deck  35  with which is comprised of two individual circuit boards,  30   a  and  30   b . Circuit boards  30   a  and  30   b  include critical components transmitters  31   a  and  31   b , up-converts  32   a  and  32   b , and low pass filters  33   a  and  33   b . In other embodiments, transmitter deck  35  may contain a single transmitter or more than two transmitters. In the embodiment shown, transmitter deck  35  mixes the incoming signal from processor deck  25  with an S-band and X-band carrier. 
     In the embodiment shown, transmitter  31   a  may operate at 30 dBm (1W), 2 GHz (S-band), and NF&lt;5 dB while transmitter  31   b  may operate at 30 dBm (1W), 8 GHz (X-band), and NF&lt;5 dB. In other embodiments, transmitter deck  35  may include a plurality of resister components such as analog integrated circuits, resistors, capacitors, inductors or transmitters. 
       FIG. 5  is an exemplary embodiment of power supply deck  45 . In the embodiment shown, the bottom deck, power supply deck  45 , includes circuit board  40  and includes critical component DC-DC converter  41 . In other embodiments, DC-DC converter  41  may also include an EMI filter. In the embodiment shown, power supply deck  45  is modularly configured to supply power to the various decks and may increase or decrease power levels by 15 volts. 
     In various embodiments, power supply deck  45  may also include a voltage regulator. 
       FIG. 6  is an exemplary embodiment of telemetry circuit board  100  in use with satellite  99 . Stackable telemetry circuit board  100  is comprised of a plurality of decks and integrated components.