Method of radar surveillance and of radar signal acquisition

Patent metadata

Field	Value
Publication number	US-9476971-B2
Application number	US-201214005813-A
Country	US
Kind code	B2
Filing date	Feb 13, 2012
Priority date	Mar 17, 2011
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

A radar includes an antennal structure, with means for transmitting an impulse signal in a band centered on F1 according to a repetition period centered on a recurrence period Tr1 and pulse width T1, with means for receiving signals by the antenna in frequency band ΔF, with a unit for processing the signals received on a set of N distance bins. The signals received are transmitted by another radar in a frequency band centered on F2 where F2−F1≦ΔF, according to a repetition period centered on a period Tr2 and pulse width T2. The signals transmitted by the two radars are asynchronous. The method comprises: slaving frequency F1 to frequency F2, by measuring the power received integrated over the N distance bins and over several recurrences, determination of period Tr2 and T2 and slaving the period centered on Tr1 to a period centered on Tr2 with Tr1=k*Tr2.

First claim

The invention claimed is:

1. A surveillance system implemented by a first radar 1, comprising:
an antenna structure,
a transmitter configured to transmit an impulse signal S 1 in a frequency band centered on a frequency F1 by a local oscillator, according to a repetition period aligned with a repetition period Tr1 and of pulse width T1,
a receiver configured to receive signals by said antenna structure in a frequency band ΔF,
a processor configured to process the signals received in a set of N distance bins,
wherein signals transmitted by a second radar 2 are received in a frequency band centered on a frequency F2 such that F2−F1≦ΔF, according to a repetition period aligned with a period Tr2 and of pulse width T2, the signals transmitted by the first radar 1 and the second radar 2 being asynchronous, and
said processor further configured to perform an Electronic Support Measure (ESM) function comprising:
A) slaving the frequency F1 to the frequency F2, by measuring the power received integrated over the set of N distance bins and over a plurality of recurrences, and
B) determining the period Tr2 and T2 and slaving of the period Tr1 to a period Tr2 with Tr1=k Tr2 or Tr1=Tr2/k with k being a positive integer.

2. The surveillance system implemented by a radar as claimed in claim 1 , wherein the processor is further configured for slaving of F1 to F2 to be carried out off-transmission of the first radar 1 and comprises varying the frequency of the local oscillator until a maximum power of the signal received is obtained, the frequency of the local oscillator being fixed to a value corresponding to the maximum of power.

3. The surveillance system implemented by a radar as claimed in claim 1 , wherein the processor is further configured for determination of Tr2 and of T2 based on a temporal autocorrelation of an amplitude of the signal received, performed over a time greater than a predetermined threshold.

4. The surveillance system implemented by a radar as claimed in claim 3 , wherein the processor is further configured for determination of Tr2 carried out off-transmission of S 1 .

5. The surveillance system implemented by a radar as claimed in claim 1 , wherein the signal transmitted by the first radar 1 is synchronized by a synchronization signal, and an autocorrelation is synchronized by this synchronization signal.

6. The surveillance system implemented by a radar as claimed in claim 1 , wherein the signal transmitted by the first radar 1 is synchronized by a synchronization signal, the synchronization signal being generated so that the signals of the second radar 2 are received in a time window determined as a function of the synchronization signal.

7. The surveillance system implemented by a radar as claimed in claim 1 , wherein during each recurrence of the repetition period comprising temporal distance bins, certain distance bins are allocated to a reception of echoes generated by pulses transmitted by the first radar 1.

8. The surveillance system implemented by a radar as claimed in claim 1 , wherein the Electronic Support Measure (ESM) function implemented by said processor is carried out in a sequential manner according to predetermined time intervals.

9. The system as claimed in claim 1 , wherein the Electronic Support Measure (ESM) function implemented by said processor is triggered subsequent to a detection of an asynchronism of the signal received with respect to the signal transmitted by the first radar 1 or to a detection of a signal power exceeding a predetermined threshold.

10. The surveillance system implemented by a radar as claimed in claim 1 , wherein the first radar 1 is configured to be successively in transmission mode and in reception mode without transmission.

11. The surveillance system implemented by a radar as claimed in claim 1 , wherein the antenna structure of the first radar 1 is configured to operate in an azimuthal rotation.

12. The surveillance system implemented by a radar as claimed in claim 1 , wherein signals received being transmitted by other radars termed radar 3, radar 4, . . . and radar n respectively associated with frequencies F3 with F3−F1≦ΔF, F4 with F4−F1≦ΔF, . . . , and Fn with Fn−F1≦ΔF with repetition periods Tr3, Tr4, . . . and Trn and with pulse widths T3, T4, . . . and Tn, the signals transmitted by the first radar 1, the radar 3, the radar 4, . . . and the radar n being asynchronous, wherein the Electronic Support Measure (ESM) function implemented by said processor is carried out sequentially for F3, Tr3, T3 then F4, Tr4, T4, . . . and then Fn, Trn, Fn.

13. A method of surveillance by a first radar 1, comprising:
transmitting with an antenna structure an impulse signal S 1 in a frequency band centered on a frequency F1 by a local oscillator, according to a repetition period aligned with a repetition period Tr1 and of pulse width T1,
receiving signals by said antenna structure in a frequency band ΔF,
processing the signals received in a set of N distance bins with a processor,
wherein signals transmitted by a second radar 2 are received in a frequency band centered on a frequency F2 such that F2−F1≦ΔF, according to a repetition period aligned with a period Tr2 and of pulse width T2, the signals transmitted by the first radar 1 and the second radar 2 being asynchronous, and further comprising the following steps carried out by said processor configured to perform an Electronic Support Measure (ESM) function:
A) slaving of the frequency F1 to the frequency F2, by measuring the power received integrated over the set of N distance bins and over a plurality of recurrences, and
B) determination of the period Tr2 and of T2 and slaving of the period aligned with Tr1 to a period aligned with Tr2 with Tr1=k Tr2 or Tr1=Tr2/k with k being a positive integer.

14. The method of surveillance by a radar as claimed in claim 13 , further comprising slaving of F1 to F2 carried out off-transmission of the first radar 1 and comprises a sub-step of varying the frequency of the local oscillator until a maximum power of the signal received is obtained, the frequency of the local oscillator being fixed to a value corresponding at the maximum of power.

15. The method of surveillance by a radar as claimed in claim 14 , wherein the determination of Tr2 is carried out off-transmission of S 1 .

16. The method of surveillance by a radar as claimed in claim 13 , wherein the determination of Tr2 and of T2 is based on a temporal autocorrelation of an amplitude of the signal received, performed over a time greater than a predetermined threshold.

17. The method of surveillance by a radar as claimed in claim 13 , wherein the signal transmitted by the first radar 1 is synchronized by a synchronization signal, and an autocorrelation is synchronized by this synchronization signal.

18. The method of surveillance by a radar as claimed in claim 13 , wherein the signal transmitted by the first radar 1 is synchronized by a synchronization signal, the synchronization signal being generated so that the signals of the second radar 2 are received in a time window determined as a function of this synchronization signal.

19. The method of surveillance by a radar as claimed in claim 13 , wherein during each recurrence of the repetition period comprising temporal distance bins, certain distance bins are allocated to a reception of echoes generated by pulses transmitted by the first radar 1.

20. The method as claimed in claim 13 , further comprising:
detecting at least one of the following: an asynchronism of

Assignees

• Cornic Pascal
• Jahan Daniel
• Garrec Patrick
• Thales Sa

Inventors

• Cornic Pascal
• Jahan Daniel
• Garrec Patrick

Classifications

• G01S2013/9064

  Physics · mapped topic

• G01S7/023

  Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques (auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36) · CPC title

• G01S7/36

  Means for anti-jamming {, e.g. ECCM, i.e. electronic counter-counter measures} · CPC title

• G01S13/02 Primary

  Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems · CPC title

• G01S7/021

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