Multi frequency spectral imaging radar system and method of target classification

• US 7,817,082 B2
• Filed: 03/11/2007
• Issued: 10/19/2010
• Est. Priority Date: 03/11/2007
• Status: Active Grant

• Current Assignee: VAWD Applied Science And Technology Corporation
• Original Assignee: VAWD Applied Science And Technology Corporation
• Inventors: Dwelly, Wesley Howard, Adams, Vinh Nguyen
• Primary Examiner(s): Gregory; Bernarr E
• Application Number:
  US12/284,635
• Publication Number:
  US 20090146869A1
• Time in Patent Office: 1,318 Days
• Field of Search: 342/21, 342/27, 342/28, 342 82-103, 342/118, 342/128, 342130-145, 342/175, 342/176, 342/179, 342188-197, 342 73- 75, 342/80, 342/147, 342149-154, 342159-162, 342/22, 342/59
• US Class Current: 342/90
• CPC Class Codes: G01S 13/532 using a bank of range gates or a memory matrix
• CPC Class Codes: G01S 7/415 Identification of targets based on measurements of movement associated with the target

Abstract

Techniques to image life forms through obstructions and at long standoff ranges employ a radar system that simultaneously transmits a plurality of RF pulse trains having different transmission frequencies and receives returns of the RF pulse trains reflected from a life form target. The returns are processed to generate digital radar data associated with the transmission frequency of each RF pulse train. The digital radar data is segmented and averaged to generate a Doppler spectrum response associated with the transmission frequency of each RF pulse train. Target classification is performed using the Doppler spectrum responses to extract biometric data describing the life form target.

Claims

1. A method comprising:

simultaneously transmitting a plurality of RF pulse trains, each of the transmitted RF pulse trains having a different transmission carrier frequency;

receiving returns of the RF pulse trains reflected from a life form target;

processing the returns to generate digital radar data associated with the transmission carrier frequency of each RF pulse train;

segmenting and processing the digital radar data to generate a Doppler spectrum response associated with the transmission carrier frequency of each RF pulse train; and

performing target classification using the Doppler spectrum responses to extract biometric data describing the life form target.

2. The method as recited in claim 1, further comprising generating an image representing the life form target from the biometric data.

3. The method as recited in claim 1, wherein the transmission carrier frequencies of the RF pulse trains comprise harmonic frequencies.

4. The method as recited in claim 1, wherein the processing of the returns to generate digital radar data associated with the transmission carrier frequency of each RF pulse train comprises:

outputting closely spaced intermediate frequencies from the returns; and

processing the intermediate frequencies with a range gated center line intermediate frequency receiver to generate the digital radar data.

5. The method as recited in claim 4, wherein the outputting of the closely spaced intermediate frequencies from the returns comprises down converting and digitizing the returns.

6. The method as recited in claim 1, wherein the segmented digital radar data is processed using fast Fourier transforms (FFT).

7. The method as recited in claim 6, wherein the segmented digital radar data processed using fast Fourier transforms (FFT) is averaged.

8. The method as recited in claim 1, wherein the digital radar data is averaged so that a product of the transmission carrier frequency and data collection duration for the digital radar data associated with each transmission carrier frequency is at least nearly equal.

9. The method as recited in claim 1, wherein the biometric data comprises at least one of life form type or life form movement.

10. The method as recited in claim 1, wherein the performing of target classification using the Doppler spectrum responses to extract biometric data describing the life form comprises determining sum and difference ratios for the Doppler spectrum responses, the sum and difference ratios used to extract the biometric data.

11. A radar system comprising:

a transmit/receive module configured to simultaneously transmit a plurality of RF pulse trains having discrete transmission carrier frequencies and to independently receive returns of the RF pulse trains reflected from a life form target;

an intermediate frequency receiver configured to generate digital radar data corresponding to each of the returns;

a signal processing module configured to segment and process the digital radar data to generate a Doppler spectrum response associated with the transmission carrier frequency of each RF pulse train; and

a classifier configured to perform target classification using the Doppler spectrum responses to extract biometric data describing the life form target.

12. The radar system as recited in claim 11, wherein the transmission carrier frequencies of the RF pulse trains comprise harmonic frequencies.

13. The radar system as recited in claim 11, wherein the transmit/receive module is configured to output closely spaced intermediate frequencies from the returns and the intermediate frequency receiver comprises a range gated center line intermediate frequency receiver configured to process the intermediate frequencies to generate the digital radar data.

14. The radar system as recited in claim 13, wherein the transmit/receive module is configured to down convert and digitize the returns to output the closely spaced intermediate frequencies.

15. The radar system as recited in claim 11, wherein the signal processing module is configured to process the segmented digital radar data using fast Fourier transforms (FFT).

16. The radar system as recited in claim 15, wherein the signal processing module is configured to average the segmented digital radar data processed using fast Fourier transforms (FFT) so that a product of the transmission carrier frequency and data collection duration for the digital radar data associated with each transmission carrier frequency is at least nearly equal.

17. The radar system as recited in claim 11, wherein the classifier is configured to determine sum and difference ratios for the Doppler spectrum responses, the sum and difference ratios used to extract the biometric data.

18. The radar system as recited in claim 11, wherein the classifier comprises a convolution network classifier.

19. The radar system of claim 11, wherein the RF pulse trains having pulse widths in the range of 2 to 200 nanoseconds and the transmission carrier frequencies of the RF pulse trains are spaced greater than 400 MHz apart.

20. A radar system comprising:

a plurality of transmit/receive channels configured to simultaneously transmit a plurality of RF pulse trains having discrete transmission carrier frequencies and to independently receive returns of the RF pulse trains reflected from a life-form target, the plurality of transmit/receive channels further configured to output intermediate frequencies corresponding to each of the returns;

an intermediate frequency receiver configured to process the intermediate frequencies to generate digital radar data associated with the transmission carrier frequency of each RF pulse train;

a signal processing module configured to segment and process the digital radar data using fast Fourier transforms (FFT) and averaging to generate a Doppler spectrum response associated with the transmission carrier frequency of each RF pulse train; and

a classifier configured to perform target classification using the Doppler spectrum responses to extract biometric data describing the life form target.

21. The radar system of claim 20, wherein the RF pulse trains having pulse widths in the range of 2 to 200 nanoseconds and the transmission carrier frequencies of the RF pulse trains are spaced greater than 400 MHz apart.