System and method for detecting and de-interleaving radar emitters using snapshots of varying lengths

• US 7,830,297 B1
• Filed: 12/20/2007
• Issued: 11/09/2010
• Est. Priority Date: 12/20/2007
• Status: Active Grant

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Orr, Matthew, Wang, Paul C., Sparrow, Mitchell, Apa, Martin
• Primary Examiner(s): Sotomayor; John B
• Application Number:
  US11/960,872
• Time in Patent Office: 1,055 Days
• Field of Search: 342/13, 342/90, 342 95- 97, 342/195, 342/40, 342/137
• US Class Current: 342/13
• CPC Class Codes: G01S 7/021 Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals

Abstract

A method of classifying radar emitters includes the steps of: (a) receiving pulses from multiple radar emitters over a plurality of consecutive first time intervals; (b) identifying pulses in each of the plurality of consecutive first time intervals corresponding to one or more first pulse trains using a first algorithm and de-interleaving the identified pulses from the plurality of first time intervals; (c) associating received pulses not identified and de-interleaved using the first algorithm with a plurality of consecutive second time intervals; and (d) identifying further pulses in each of the plurality of consecutive second time intervals corresponding to one or more second pulse trains using a second algorithm different from the first algorithm and de-interleaving the identified further pulses from the pulses associated with the plurality of consecutive second time intervals. Each consecutive second time interval is formed from two or more consecutive first time intervals.

Claims

1. A method of classifying radar emitters comprising the steps of:

(a) receiving pulses from multiple radar emitters during a plurality of consecutive first time intervals;

(b) identifying pulses in each of the plurality of consecutive first time intervals corresponding to one or more first pulse trains using a first algorithm and de-interleaving the identified pulses from the plurality of first time intervals;

(c) associating received pulses not identified and not de-interleaved using the first algorithm with a plurality of consecutive second time intervals, each consecutive second time interval formed from two or more consecutive first time intervals; and

(d) identifying further pulses in each of the plurality of consecutive second time intervals corresponding to one or more second pulse trains using a second algorithm and de-interleaving the identified further pulses from the pulses associated with the plurality of consecutive second time intervals.

2. The method of claim 1, wherein the step (b) comprises

identifying a first train of pulses received from a first radar source in a first time interval in the plurality of consecutive first time intervals using the first algorithm;

establishing a first tracking filter associated with the identified first train of pulses received from the first radar source; and

de-interleaving the identified first train of pulses produced by the first radar source from the received pulses in the first time interval.

3. The method of claim 2, wherein the step (b) further comprises

identifying a second train of pulses in a second time interval in the plurality of consecutive first time intervals using the tracking filter, the second time interval following the first time interval in time, the identified second train of pulses produced by the first radar source;

removing the identified second train of pulses from the second time interval;

identifying a further train of pulses received from a second radar source in the second time interval using the first algorithm;

establishing a further tracking filter associated with the identified further train of pulses received from the second radar source; and

de-interleaving the identified further train of pulses produced by the second radar source from the pulses of the second time interval remaining after the second train of pulses produced by the first radar source is removed.

4. The method of claim 3, wherein the first algorithm is a quantized pulse repetition interval (PRI) algorithm.

5. The method of claim 1, wherein the step (d) further comprises

categorizing the pulses in the plurality of consecutive second time intervals based on pulse descriptor words (PDWs);

forming clusters of the pulses in the plurality of consecutive second time intervals based on the PDWs; and

extracting pulses from at least one of the formed clusters based on pulse repetition intervals (PRIs) between the extracted pulses.

6. The method of claim 5, wherein the step of extracting includes de-interleaving pulses from the at least one of the formed clusters using a differential time of arrival (DTOA) histogram technique.

7. The method of claim 5, wherein the step of extracting includes de-interleaving pulses from the at least one of the formed clusters using a pattern recognition technique.

8. The method of claim 1, further comprising the steps of:

(e) associating pulses in the plurality of consecutive second time intervals not identified and de-interleaved using the second algorithm with a plurality of consecutive third time intervals, each consecutive third time interval being formed from two or more consecutive second time intervals; and

(f) identifying still further pulses in each of the plurality of consecutive third time intervals corresponding to one or more third pulse trains using a third algorithm and de-interleaving the still further pulses from the pulses associated with the plurality of consecutive third time intervals.

9. The method of claim 8, wherein the step (f) further comprises

categorizing the pulses in the plurality of consecutive time third intervals based on pulse descriptor words (PDWs);

forming clusters of the pulses in the plurality of consecutive third time intervals based on the PDWs; and

extracting pulses from at least one of the formed clusters based on pulse repetition intervals (PRIs) between the extracted pulses.

10. The method of claim 9, wherein the step of extracting includes de-interleaving pulses from the at least one of the formed clusters using a Hough transform technique.

11. The method of claim 9, wherein the step of extracting included de-interleaving pulses from the at least one of the formed clusters using a pattern recognition technique.

12. A method of classifying radar emitters comprising the steps of:

(a) receiving pulses from multiple radar emitters during a plurality of consecutive first time intervals;

(b) forming a first snapshot of pulse descriptor words (PDWs) for the pulses received during a first time interval in the plurality of consecutive first time intervals;

(c) identifying PDWs corresponding to one or more pulse trains in the first snapshot using a first algorithm and removing the identified PDWs from the first snapshot;

(d) forming a second snapshot from the PDWs remaining in the first snapshot, the second snapshot corresponding to a second time interval longer than the first time interval; and

(e) identifying further PDWs corresponding to one or more pulse trains in the second snapshot using a second algorithm and removing the identified further PDWs from the second snapshot.

13. The method of claim 12, further comprising

(f) forming a third snapshot from the PDWs remaining in the second snapshot, the third snapshot corresponding to a third time interval longer than the second time interval;

and

(g) identifying still further PDWs corresponding to one or more pulse trains in the third snapshot using a third algorithm and removing the identified still further PDWs from the third snapshot.

14. The method of claim 13, wherein the first snapshot is a 5 msec snapshot, the second snapshot is a 30 msec snapshot, and the third snapshot is an 80 msec snapshot.

15. The method of claim 13, wherein the step (e) comprises:

forming clusters of the PDWs in the second snapshot, and

extracting PDWs from at least one of the formed clusters based on pulse repetition intervals (PRIs) between the extracted PDWs as processed by the second algorithm; and

the step (g) comprises;

forming clusters of the PDWs in the third snapshot, and

extracting PDWs from at least one of the formed clusters in the third snapshot based on pulse repetition intervals (PRIs) between the PDWs extracted from the third snapshot as processed by the third algorithm.

16. A system for classifying radar emitters comprising

a receiver for receiving a plurality of signals from radar emitters,

a processor coupled to the receiver and configured for

(a) generating data components for each signal received from the radar emitters,

(b) forming multi-dimensional samples from the generated data components,

(c) placing the multi-dimensional samples corresponding to signals received during a first period into a first snapshot,

(d) extracting multi-dimensional samples from the first snapshot corresponding to one or more first pulse trains identified using a first algorithm,

(e) placing the multi-dimensional samples remaining in the first snapshot in a second snapshot corresponding to signals received during a second time frame longer than the first time frame, and

(f) extracting multi-dimensional samples from the second snapshot corresponding to one or more second pulse trains identified using a second algorithm.

17. The system of claim 16, wherein the processor is configured for de-interleaving multi-dimensional samples from the first snapshot using a quantized pulse repetition interval (PRI) technique.

18. The system of claim 16, wherein the processor is configured for de-interleaving multi-dimensional samples from the second snapshot using one of a differential time of arrival (DTOA) histogram technique, a spectrum estimation technique, or a pulse repetition interval (PRI) detection technique.

19. The system of claim 16, including

a storage device for storing the first and second snapshots representing the signals received.