Digitally programmable radio modules for transponder systems

• US 5,712,628 A
• Filed: 08/31/1995
• Issued: 01/27/1998
• Est. Priority Date: 08/31/1995
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Phillips, William C., Minarik, Ronald W., Schmidt, Kenneth M., Pascale, Michael V.
• Primary Examiner(s): Zimmerman, Brian
• Assistant Examiner(s): Beaulieu, Yonel
• Application Number:
  US08/522,059
• Time in Patent Office: 880 Days
• Field of Search: 340/825.54, 340/505, 340/568, 340/572, 340/825.35, 340/825.49, 342/42, 342/44, 342/51, 342/29, 342/30, 342/38, 342/39, 455/49.1, 235/380, 235/382.5, 235/382
• US Class Current: 340/10.51
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: H03D 7/163 the local oscillations of at least two of the frequency changers being derived from a single oscillator
• CPC Class Codes: H04B 1/0003 Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain digital baseband systems H04L25/00; digital modulation/demodulation H04L27/00; CDMA H04B1/707; TDMA H04B7/2643; image transmission H04N5/00
• CPC Class Codes: H04B 1/001 Channel filtering, i.e. selecting a frequency channel within the SDR system multiplexing of multicarrier modulation signals being represented by different frequencies H04L5/06; multiplexing of multicarrier modulation signals H04L5/023
• CPC Class Codes: H04B 1/0014 using DSP [Digital Signal Processor] quadrature modulation and demodulation
• CPC Class Codes: H04B 1/0017 Digital filtering H04B1/001 takes precedence; digital filters per se H03H17/00
• CPC Class Codes: H04B 1/0039 using DSP [Digital Signal Processor] quadrature modulation and demodulation
• CPC Class Codes: H04B 1/0057 using diplexing or multiplexing filters for selecting the desired band
• CPC Class Codes: H04B 1/26 for superheterodyne receivers multiple frequency-changing H03D7/16
• CPC Class Codes: H04B 1/40 Circuits
• CPC Class Codes: H04B 2001/0491 with frequency synthesizers, frequency converters or modulators

Abstract

A programmable digital radio is configured to perform transponder functions. A receiver in the programmable digital radio receives analog signals from an interrogator and digitizes the analog signals to produce digital interrogation signals. The digital interrogation signals are processed digitally and valid interrogations are detected. Processing includes detection of pulses, determination of each pulse'"'"'s threshold, determination of intervals between pulses and whether the intervals meet mode criteria, and determination of priority of output of digital messages encoded in the pulses. At least one message is supplied to a transmit module in the programmable radio. The transmit module performs diversity processing on the received message to determine to which received signal to reply, produces reply data and modulates the reply data to produce intermediate frequency signals. The intermediate frequency signals are then converted to analog signals which are transmitted to the interrogator.

Claims

1. A transponder comprising:

a programmable receive module for processing a received interrogation signal into a transponder signal,

said programmable receive module including at least one receive field programmable gate array, reconfigurable in accordance with first configuration data, for processing the received interrogation signal in one of a plurality of interrogation modes specified by the first configuration data to provide the transponder signal; and

a programmable transmit module, coupled to said programmable receive module, for processing the transponder signal to generate and transmit a response signal.

2. The transponder of claim 1, wherein said programmable transmit module comprises a transmit field programmable gate array, reconfigurable in accordance with second configuration data, for processing the transponder signal into the response signal in the corresponding one of the plurality of interrogation modes specified by the second configuration data.

3. The transponder of claim 2, wherein said programmable transmit module further comprises:

a memory for storing the second configuration data; and

processing means, coupled to said memory, for reconfiguring said transmit field programmable gate array in accordance with the second configuration data.

4. The transponder of claim 1, wherein the plurality of interrogation modes comprise communication, navigation and identification modes.

5. The transponder of claim 4, wherein the plurality of modes comprise mode C for requesting aircraft altitude and mode 3A for requesting aircraft identification.

6. The transponder of claim 1, wherein said programmable receive module comprises:

a tunable frequency converter for down converting the received interrogation signal into an intermediate frequency signal;

a digital converter for converting the intermediate frequency signal into a digital signal and for providing the digital signal to the at least one receive field programmable gate array;

a memory for storing the first configuration data; and

processing means, coupled to said memory, for reconfiguring the at least one receive field programmable gate array in accordance with the first configuration data.

7. The transponder of claim 6, wherein said digital converter, said memory, said processing means and the at least one receive field programmable gate array are housed within a receive digital submodule, said digital converter being electrically isolated within said receive digital submodule.

8. The transponder of claim 1, wherein the at least one receive field programmable gate array is configurable to convert the received interrogation signal into a digital signal and to perform pulse detection, pulse width discrimination and interval discrimination processing on the digital signal to provide the transponder signal.

9. The transponder of claim 1, further comprising:

a plurality of antennas for receiving radio frequency signals to provide the received interrogation signal and a plurality of respective received interrogation signals; and

a plurality of additional programmable receive modules, each respectively including at least one receive field programmable gate array, for processing the respective received interrogation signals into respective transponder signals,

said programmable transmit module performing diversity processing to determine which of the transponder signal and the respective transponder signals is the strongest and providing the response signal to the antenna which received the strongest radio frequency signal for transmission.

10. The transponder of claim 1, wherein the received interrogation signal is a radio frequency signal having a frequency in a range of 2-2,000 Mhz.

11. The transponder of claim 1, wherein said programmable receive module and said programmable transmit module are plug-in modules.

12. A programmable radio comprising:

a receive module for processing a received interrogation signal into a transponder signal,

said receive module including at least one receive field programmable gate array, reconfigurable in accordance with first configuration data, for processing the received interrogation signal in one of a plurality of interrogation modes specified by the first configuration data to provide the transponder signal; and

a transmit module, coupled to said receive module, for processing the transponder signal to generate and transmit a response signal.

13. The programmable radio of claim 12, wherein said transmit module comprises a transmit field programmable gate array, reconfigurable in accordance with second configuration data, for processing the transponder signal into the response signal in the corresponding one of the plurality of interrogation modes specified by the second configuration data.

14. The programmable radio of claim 13, wherein said transmit module further comprises:

a memory for storing the second configuration data; and

processing means, coupled to said memory, for reconfiguring said transmit field programmable gate array in accordance with the second configuration data.

15. The programmable radio of claim 12, wherein the plurality of interrogation modes comprise communication, navigation and identification modes.

16. The programmable radio of claim 15, wherein the plurality of modes comprise mode C for requesting aircraft altitude and mode 3A for requesting aircraft identification.

17. The programmable radio of claim 12, wherein said receive module comprises:

a tunable frequency converter for down converting the received interrogation signal into an intermediate frequency signal;

a digital converter for converting the intermediate frequency signal into a digital signal and for providing the digital signal to the at least one receive field programmable gate array;

a memory for storing the first configuration data; and

processing means, coupled to said memory, for reconfiguring the at least one receive field programmable gate array in accordance with the first configuration data.

18. The programmable radio of claim 12, wherein said digital converter, said memory, said processing means and the at least one receive field programmable gate array are housed within a receive digital submodule, said digital converter being electrically isolated within said receive digital submodule.

19. The programmable radio of claim 12, wherein the at least one receive field programmable gate array is configurable to convert the received interrogation signal into a digital signal and to perform pulse detection, pulse width discrimination and interval discrimination processing on the digital signal to provide the transponder signal.

20. The programmable radio of claim 12, further comprising:

a plurality of antennas for receiving radio frequency signals to provide the received interrogation signal and a plurality of respective received interrogation signals; and

a plurality of additional receive modules, each respectively including at least one receive field programmable gate array, for processing the respective received interrogation signals into respective transponder signals,

said transmit module performing diversity processing to determine which of the transponder signal and the respective transponder signals is the strongest and providing the response signal to the antenna which received the strongest radio frequency signal for transmission.

21. The programmable radio of claim 12, wherein the received interrogation signal is a radio frequency signal having a frequency in a range of 2-2,000 Mhz.

22. The programmable radio of claim 12, wherein said receive module and said transmit module are plug-in modules.