Method for independently setting range resolution, Doppler resolution, and processing gain of a pseudo-random coded radar system

• US 7,382,310 B1
• Filed: 01/03/2007
• Issued: 06/03/2008
• Est. Priority Date: 01/03/2006
• Status: Active Grant

• Current Assignee: Gregory Hubert Piesinger
• Original Assignee: Gregory Hubert Piesinger
• Inventors: Piesinger, Gregory Hubert
• Primary Examiner(s): Sotomayor; John B
• Application Number:
  US11/649,150
• Time in Patent Office: 517 Days
• Field of Search: 342/27, 342/28, 342 99-101, 342114-116, 342131-137, 342/192, 342/196, 342200-204, 340/541, 340/545.3, 340/554
• US Class Current: 342/28
• CPC Class Codes: G01S 13/325 using transmission of coded signals, e.g. P.S.K. signals
• CPC Class Codes: G01S 13/536 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves
• CPC Class Codes: G01S 13/583 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets

Abstract

Methods are disclosed for independently setting the range resolution, Doppler resolution, and pulse compression processing gain of a Doppler radar system. Higher Doppler resolution is achieved by segmenting and spreading apart a pseudo-random code (PRC) to increase the processing dwell time on a target. Simultaneous high and low range resolution is obtained by interleaving a second segmented low resolution PRC into the time gaps between a first segmented high resolution PRC.

Claims

1. A method for independently setting range resolution, Doppler resolution, and pulse compression processing gain in a pseudo-random coded Doppler radar comprising:

generating a pseudo-random code (PRC);

generating a segmented PRC by dividing said PRC into a plurality of PRC sequences;

generating a spread segmented PRC by spreading the said PRC sequences of said segmented PRC apart in time;

transmitting said spread segmented PRC into a surveillance area;

receiving a target signal comprised of reflections from radar targets in said surveillance area due to said transmitting of said spread segmented PRC;

generating a bank of matched filter outputs by passing said target signal through a plurality of filters where each filter is matched to a different Doppler shifted version of said spread segmented PRC; and

detecting moving targets in said surveillance area from said bank of matched filter outputs.

2. A method as claimed in claim 1 wherein the number of code chips in said PRC is based on a desired pulse compression processing gain.

3. A method as claimed in claim 1 wherein the code chip duration of said PRC is based on a desired radar range resolution.

4. A method as claimed in claim 1 wherein the duration of the spread segmented PRC is based on a desired Doppler resolution.

5. A method as claimed in claim 1 wherein said transmitting is performed by modulation of a CW carrier.

6. A method as claimed in claim 1 wherein said transmitting is performed by bi-phase modulating a CW carrier using said spread segmented PRC.

7. A method as claimed in claim 1 wherein said bank of matched filter outputs is implemented using FFT processing.

8. A method for simultaneously providing multiple range resolutions in a pseudo-random coded Doppler radar comprising:

generating multiple pseudo-random codes (PRCs) in which each PRC uses a different code and code chip duration;

generating multiple segmented PRCs by dividing each of the said multiple PRCs into a plurality of segmented PRC sequences;

generating multiple spread segmented PRCs by spreading the said segmented PRC sequences of each of the said multiple segmented PRCs apart in time;

generating a combined spread segmented PRC by interleaving the said segmented PRC sequences of all the said multiple spread segmented PRCs;

transmitting said combined spread segmented PRC into a surveillance area;

receiving a combined target signal comprised of reflections from radar targets in said surveillance area due to said transmitting of said combined spread segmented PRC;

generating multiple banks of matched filter outputs by passing said combined target signal through a plurality of filter banks in which each filter of each filter bank is matched to a different Doppler shifted version of one of said spread segmented PRC in the group of said multiple spread segment PRCs;

detecting moving targets in different resolution areas of said surveillance area from each bank of matched filter outputs in said multiple banks of matched filter outputs.

9. A method as claimed in claim 8 wherein the number of multiple PRCs is two.

10. A method as claimed in claim 8 wherein the number of code chips in each PRC of said PRCs is based on a desired pulse compression processing gain for that PRC.

11. A method as claimed in claim 8 wherein the code chip duration of each PRC of said multiple PRCs is based on a desired radar range resolution for that PRC.

12. A method as claimed in claim 8 wherein the duration of the said combined spread segmented PRC is based on a desired Doppler resolution.

13. A method as claimed in claim 8 wherein said transmitting is performed by modulation of a CW carrier.

14. A method as claimed in claim 8 wherein said transmitting is performed by bi-phase modulating a CW carrier using said combined spread segmented PRC.

15. A method as claimed in claim 8 wherein each bank of matched filter outputs of said multiple banks of matched filter outputs is implemented using FFT processing.

16. A method for operating a radar system comprising:

identifying a Doppler period, a processing gain, and a range resolution for said radar system;

defining a pseudo-random code (PRC) having a code chip duration determined in response to said range resolution and a number of code chips determined in response to said processing gain;

generating a spread segmented PRC by distributing portions of said PRC throughout said Doppler period;

transmitting said spread segmented PRC into a surveillance area;

receiving a target signal comprised of reflections from radar targets in said surveillance area due to said transmitting of said spread segmented PRC; and

processing said target signal in a radar signal processor.

17. A method as claimed in claim 16 wherein said processing activity comprises passing said target signal through a matched filter, said filter being matched to said spread segmented PRC.

18. A method as claimed in claim 17 wherein said processing activity comprises passing said target signal through a plurality of matched filters, where each of said filters is matched to a different Doppler shifted version of said spread segmented PRC.

19. A method as claimed in claim 16 wherein:

said range resolution is a first range resolution, said PRC is a first PRC, said spread segmented PRC is a first spread segmented PRC, and said first spread segmented PRC is characterized by segments of first code chips spread apart in time by inter-segment regions;

said identifying activity identifies a second range resolution for said radar system;

said defining activity defines a second PRC having a code chip duration determined in response to said second range resolution;

said generating activity generates a second spread segmented PRC by distributing portions of said second PRC throughout said Doppler period, said second spread segmented PRC being characterized by segments of second code chips spread apart in time by inter-segment regions;

said generating activity also interleaves said first and second PRCs so that said segments of said first code chips reside in inter-segment regions for said second PRC and second code chips for said second PRC reside in said inter-segment regions for said first PRC; and

said first code chips exhibit a greater duration than said second code chips.