Method of interference suppression in a radar system

• US 6,768,444 B2
• Filed: 07/24/2003
• Issued: 07/27/2004
• Est. Priority Date: 08/11/2000
• Status: Expired due to Fees

• Current Assignee: BAE Systems Integrated System Technologies Ltd. (BAE Systems Plc)
• Original Assignee: Alenia Marconi Systems Limited
• Inventors: Langsford, Peter
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US10/344,264
• Publication Number:
  US 20040027268A1
• Time in Patent Office: 369 Days
• Field of Search: 342/13-20, 342/175, 342/192-197, 342/368, 342/378-384, 342/89-103, 342/159-164, 342/189
• US Class Current: 342/17
• CPC Class Codes: G01S 7/2813 Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays specially adapted to secondary radar systems G01S13/762; aerials or aerials systems H01Q21/29, H01Q25/00
• CPC Class Codes: G01S 7/36 Means for anti-jamming , e.g. ECCM, i.e. electronic counter-counter measures

Abstract

The invention relates to a method of interference suppression in a radar system (10) and also to a system (10) operating according to the method. The system (10) incorporates a first antenna (40) and associated electronic circuits for emitting interrogating radar radiation towards a remote scene (S). Moreover, the system (10) also incorporates a second antenna (45) and associated electronic circuits for receiving interrogating radiation reflected from the scene (S) and generating correponding first and second processed signals. The first and second processed signals correspond to a broader main beam response of the antenna (45) and to a narrower main beam response thereof respectively. By mutually comparing the first and second processed signals, the system (10) is operable to identify those second processed signals affected by interference from the scene (S). The system (10) also incorporates electronic units (430, 440) operable to calculate adaptive weights for modifying the narrower response to steer its nulls in directions of interfering sources in the scene (S) when the narrower response is used to generate an overall output from the system (10), the units operable to selectively use second signal samples identified as being subject to interference for calculating the adaptive weights. The system (10) is operable to store its first and second signals for a period not less than that associated with updating the adaptive weights, thereby providing the system (10) with enhanced interference suppresssion characteristics.

Claims

1. A method of non-continuous jamming interference suppression in a radar system incorporating emitting means for emitting interrogating radiation towards a remote scene and receiving means for receiving corresponding echo radiation returned from the scene in response to the interrogating radiation, the method including the steps of:

(a) emitting the interrogating radiation from the emitting means towards a selected region of the scene;

(b) receiving first echo radiation substantially from the selected region of the scene at the receiving means and generating a corresponding first received signal;

(c) receiving second echo radiation substantially from the selected region and other regions surrounding the selected region and generating a corresponding second received signal;

(d) mutually comparing the first and second signals and determining therefrom portions of the first signal subject to non-continuous jamming interference;

(e) repeating steps (a) to (d) where necessary for one or more other selected regions until sufficient samples of the signals are available for performing an adaptive weight calculation;

(f) selectively using the portions of the first signal where non-continuous jamming interference is detected in the calculation for calculating adaptive weight coefficients;

(g) processing the signals using the adaptive weight coefficients to generate an overall output from the system corresponding to radiation reflected from one or more selected regions, the overall output being at least partially corrected for non-continuous jamming interference enabling target detection during periods of such interference; and

(h) repeating steps (a) to (g) until all the selected regions of the scene to be interrogated have been interrogated.

2. A method according to claim 1 wherein the signals are stored in storing means of the system for a period not less than that required for updating the adaptive weight coefficients.

3. A method according to claim 1 wherein, in step (d), a condition where the second signal is greater in magnitude than the magnitude of the first signal subject to a threshold scaling constant for a given selected region is indicative that the first signal is affected by interference.

4. A method according to claim 3 wherein the threshold scaling constant is made variable for coping with different types of interference.

5. A method according to claim 1 wherein the receiving means is electronically steerable to different selected regions of the scene.

6. A method according to claim 1 wherein the receiving means is mechanically steerable to different selected regions of the scene.

7. A method according to claim 1 wherein the receiving means comprises a multielement antenna and the adaptive weight coefficients are used to vectorially multiply signals generated by the elements in response to radiation received from the scene thereat for generating the overall output from the system.

8. A method according to claim 1 wherein, in step (a), the emitting means is electronically steerable to different selected regions of the scene.

9. A method according to claim 1 wherein, in step (a), the emitting means is mechanically steerable to different selected regions of the scene.