Method for jamming synthetic aperture radars and associated device

Patent metadata

Field	Value
Publication number	US-10852391-B2
Application number	US-201716074688-A
Country	US
Kind code	B2
Filing date	Jan 30, 2017
Priority date	Feb 5, 2016
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

A method for jamming airborne SAR radar implemented by a jamming device includes at least two cooperating units surrounding an area on the ground to be protected, at least two units providing a radar-detection function and at least one unit providing a radar-jamming function, each unit being interlinked by a two-way data link and being synchronized by a common clock, the method comprises a step of identifying the signals received and whether the received signals correspond to SAR signals; a step of characterizing the received SAR signal over a short duration; a step of computing a filter adapted to the signal; a step of carrying out pulse compression of the signal; a step of iteratively periodically characterizing the signal over a long duration; a step of computing the jamming signals to be transmitted; a step of transmitting the jamming signals.

First claim

The invention claimed is:

1. A method for jamming at least one SAR-type airborne radar implemented by a radar-jamming device comprising a group of at least two cooperating units surrounding an area on the ground to be protected, at least two units of said group providing a radar-detection function and at least one unit of said group providing a radar-jamming function, each unit providing the radar-detection function comprising a receiving and processing module configured to analyze the received signals, each unit providing the radar-jamming function being configured to generate and to transmit jamming signals, each unit being interlinked by at least one two-way data link and being synchronized by a common clock, said method being wherein it comprises a step (Etp 10 ) of identifying the signals received by the receivers and whether said received signals correspond to synthetic aperture radar signals:
a step (Etp 20 ) of characterizing the received SAR signal over a predetermined duration that is shorter than the duration of a recurrence of the SAR signal;
a step (Etp 30 ) of computing a filter adapted to the pulses of the received SAR signal;
a step (Etp 40 ) of carrying out pulse compression of the received SAR signal on each recurrence using said adapted filter, making it possible to obtain the phase in the distance boxes, thereby making it possible to obtain the Doppler history linked to the movement of the radar carrier;
a step (Etp 50 ) of iteratively periodically characterizing the received signal over a predetermined duration that is longer than a recurrence of the SAR signal so as to establish, from one recurrence to the next, the speed of movement of the radar and the distance between said radar and the area to be protected;
a step (Etp 60 ) of computing the jamming signals to be transmitted for each point of the area to be protected so as to jam the SAR radar coherently on the distance axis and on the Doppler axis;
a step (Etp 70 ) of transmitting the computed jamming signals.

2. The method as claimed in claim 1 , wherein the method comprises a step (Etp 25 ) of time and frequency windowing so as to limit the detection volume of the processing module to a time window and to a bandwidth corresponding to the characteristics observed on the SAR signal.

3. The method as claimed in claim 1 , wherein a SAR signal is identified on the basis of predetermined criteria relating to its waveform and to the orientation of the antenna beam of the SAR radar.

4. The method as claimed in claim 1 , wherein at least one unit providing the radar-jamming function comprises a memory table in which various jamming signals are pre-recorded and wherein the jamming signals to be transmitted are not computed but loaded from the memory zone.

5. The method as claimed in claim 1 , wherein the parameters of the jamming signals are modified over the course of one and the same jamming sequence so as to modify the area to be protected.

6. A device for jamming SAR-type airborne radars that is configured to implement the jamming method as claimed in claim 1 , said device being wherein it comprises a group of at least two cooperating units surrounding an area on the ground to be protected, at least two units of said group providing a radar-detection function and at least one unit of said group providing a radar-jamming function, each unit providing the radar-detection function comprising a receiving and processing module configured to analyze the received signals, each unit providing the radar-jamming function being configured to generate and to transmit jamming signals, each unit being interlinked by a two-way data link and being synchronized by a common clock.

7. The device as claimed in claim 1 , wherein each unit provides the radar-jamming function.

8. The device as claimed in claim 6 , wherein the transmitter module of each unit providing the radar-jamming function comprises a movable antenna configured to stay pointed in the direction of the SAR radar to be jammed.

9. The device as claimed in claim 6 , wherein the receiver module of the units providing the radar-detection function comprises a superheterodyne-type receiver.

10. The device as claimed in claim 6 , wherein each unit providing the radar-detection function comprises an interferometry antenna.

11. The device as claimed in claim 6 , wherein at least one radar detector comprises a memory table in which various jamming signals are pre-recorded.

12. The device as claimed in claim 6 , wherein the synchronization clock is a GPS clock.

13. The device as claimed in claim 6 , wherein at least one data link is a secure data link.

14. The device as claimed in claim 6 , wherein at least one element of the group of at least two units is mobile.

Assignees

• Thales Sa

Inventors

• Cornic Pascal
• Quellec Jean-Michel
• Legros Patrick

Classifications

• H04K3/42 Primary

  characterized by the control of the jamming frequency or wavelength · CPC title

• G01S7/38 Primary

  Jamming means, e.g. producing false echoes · CPC title

• G01S13/90

  using synthetic aperture techniques {, e.g. synthetic aperture radar [SAR] techniques} · CPC title

• H04K3/40

  Jamming having variable characteristics · CPC title

• G01S7/021

  Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals · CPC title