Multiple radar interference suppressor

• US 5,317,320 A
• Filed: 11/27/1992
• Issued: 05/31/1994
• Est. Priority Date: 11/27/1992
• Status: Expired due to Term

• Current Assignee: General Dynamics C4 Systems Incorporated (General Dynamics Corporation)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Grover, Richard K., Kingsbury, Keith M.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US07/982,528
• Time in Patent Office: 550 Days
• Field of Search: 342/59, 342/102, 342/103, 342/159, 342/119
• US Class Current: 342/159
• CPC Class Codes: G01S 13/87 Combinations of radar systems, e.g. primary radar and secondary radar
• CPC Class Codes: G01S 7/003 Transmission of data between radar, sonar or lidar systems and remote stations
• CPC Class Codes: G01S 7/02 of systems according to group G01S13/00
• CPC Class Codes: G01S 7/023 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 Class Codes: G01S 7/0233 Avoidance by phase multiplex
• CPC Class Codes: G01S 7/0234 Avoidance by code multiplex
• CPC Class Codes: G01S 7/0235 Avoidance by time multiplex

Abstract

A multiple radar interference suppressor for use in a missile scoring system. The multiple radar interference suppressor phase locks the pulse repetition frequency of each drone (unmanned) aircraft to one other drone of the plurality of aircrafts. The phase of the pulse repetition frequency of each of the transmitting radars of the drones is slightly offset from one another. As a result, mutual interference among the drones transmitting radar signals and receiving radar signals of other drones is overcome. Lastly, the transmitted signals and received signals are encoded so that unwanted reflections and scattering from a target may be substantially eliminated or suppressed.

Claims

1. A multiple radar interference suppressor comprising:

a plurality of sources of radar transmit signals, said radar transmit signals having approximately the same frequency;

means for receiving said radar transmit signals, said means for receiving coupled to said plurality of sources of radar transmit signals;

means for phase locking a pulse repetition frequency of said received radar transmit signals of a first of said plurality of sources to a second of said plurality of said sources, said means for phase locking coupled to said means for receiving; and

means for phase offsetting the pulse repetition frequency of said locked, received radar transmit signals of said first and second sources, said means for phase offsetting coupled between said means for receiving and said means for phase locking.

2. A multiple radar interference suppressor as claimed in claim 1, wherein there is further included:

means for pseudorandomly encoding said radar transmit signals of each of said plurality of sources, said means for pseudorandomly encoding coupled to said means for phase locking; and

transmit means for transmitting said pseudorandomly encoded radar transmit signals, said transmitter means coupled to said means for pseudorandomly encoding.

3. A multiple radar interference suppressor as claimed in claim 2, wherein there is further included means for pseudorandomly enabling said means for receiving so that said means for receiving only radar transmit signals encoded by said means for pseudorandomly encoding while rejecting improperly coded radar transmit signals.

4. A multiple radar interference suppressor as claimed in claim 3, wherein said means for receiving includes:

a plurality of receive channel means, each of said receive channel means for sampling said radar transmit signals at a high sample rate; and

a plurality of antenna means corresponding to said receive channel means, each of said antenna means for receiving said radar transmit signals, said plurality of antenna means coupled to said plurality of receive channel means on a one-for-one basis.

5. A multiple radar interference suppressor as claimed in claim 4, wherein said means for receiving further includes a plurality of video channel group means for receiving said sampled radar transmit signals and providing a plurality of bits describing the rate of change of said received radar transmit signals, said video channel group means coupled to a corresponding receive channel means on a one-for-one basis.

6. A multiple radar interference suppressor as claimed in claim 5, wherein each of said video channel group means includes a plurality of video channel means, each of said video channel means providing one-bit indicating a slope of said received radar transmit signals, each of said plurality of video channel means being coupled to said corresponding receive channel means.

7. A multiple radar interference suppressor as claimed in claim 6, wherein said means for receiving further includes:

data commutator means coupled to each of said plurality of video channel means of each of said plurality of video channel group means, said data commutator means for storing each of said plurality of slope bits of each of said plurality of video channel means; and

transmitter means for transmitting each of said stored slope bits to a central collection station.

8. A multiple radar interference suppressor as claimed in claim 6, wherein said means for phase locking includes locking channel means for receiving samples of said received radar transmit signals and producing a locking bit stream of said received radar transmit signal, said locking channel means being couple to a predefined one of said plurality of receive channel means.

9. A multiple radar interference suppressor as claimed in claim 8, wherein said means for phase locking further includes:

phase locked loop means for locking said pulse repetition frequency of said received radar transmit signal to a pulse repetition frequency of a transmitted radar transmit signal of a particular source, said phase locked loop means being coupled to said locking channel means; and

oscillator means for providing signals for controlling said sampling by said receive channel means, said oscillator means coupled to said phase locked loop means.

10. A multiple radar interference suppressor as claimed in claim 9, wherein said means for phase locking further including:

count generator means for producing pulse streams representing the sampling rate of said receive channel means, of said video channel means and of said transmitter means, said count generator means coupled to said oscillator means; and

range gate means for storing and forwarding said pulse streams of said receive channel, said video channel means, and said transmitter means, said range gate means coupled to said receive channel means, to said video channel means, and to said transmitter means.

11. A multiple radar interference suppressor as claimed in claim 4, wherein:

said means for pseudorandomly enabling is coupled to each of said plurality of received channel means; and

said means for pseudorandomly encoding and said means for pseudorandomly enabling are synchronized.

12. A multiple radar interference suppressor as claimed in claim 10, wherein each of said receive channel means includes:

a high pass filter coupled to one of said plurality of antenna means;

a first RF amplifier coupled to said high pass filter;

a low pass filter coupled to said first RF amplifier;

a second RF amplifier coupled to said low pass filter; and

fast switching means coupled to said second RF amplifier and to said range gate means.

13. A multiple radar interference suppressor as claimed in claim 10, wherein each of said video channel means includes:

slow switching means coupled to said receive channel means;

a low pass filter coupled to said slow switching means;

a first amplifier coupled to said low pass filter;

a capacitive switched filter coupled to said first amplifier;

a second amplifier coupled to said capacitive switched filter; and

a continuously variable slope modulator coupled to said second amplifier and to said range gate means.

14. A multiple radar interference suppressor as claimed in claim 10, wherein said count generator means includes:

a counter coupled to said oscillator means;

a programmable read only memory coupled to said counter; and

a register coupled between said programmable read only memory and said range gate means.

15. A missile scoring system for determining the affect of a fired missile on a plurality of drone aircraft (drone), said missile scoring system comprising:

each of said plurality of drones including a source of radar transmit signals, each said radar transmit signal having approximately the same frequency as other signals of said drones;

each of said plurality of drones including;

means for receiving said radar transmit signals, said means for receiving coupled to said plurality of sources of radar transmit signals;

means for phase locking a pulse repetition frequency of said received radar transmit signals of said one drone to another of said plurality of drones, said means for phase locking coupled to said means for receiving;

means for phase offsetting the pulse repetition frequency of said locked, received radar transmit signals of said one and another of said drones, said means for phase offsetting coupled between said means for receiving and said means for phase locking; and

means for transmitting a slope of said received radar transmit signals to an earth station for subsequent scoring analysis.

16. A missile scoring system as claimed in claim 15, wherein there is further included:

means for pseudorandomly encoding said radar transmit signals of each of said plurality of sources, said means for pseudorandomly encoding coupled to said means for phase locking; and

transmit means for transmitting said pseudorandomly encoded radar transmit signals, said transmitter means coupled to said means for pseudorandomly encoding.

17. A missile scoring system as claimed in claim 16, wherein there is further included means for pseudorandomly enabling said means for receiving only radar transmit signals encoded by said means for pseudorandomly encoding while rejecting improperly coded radar transmit signals.

18. A missile scoring system as claimed in claim 15, wherein said means for receiving includes:

a plurality of receive channel means, each of said receive channel means for sampling said radar transmit signals at a high sample rate; and

a plurality of antenna means corresponding to said receive channel means, each of said antenna means for receiving said radar transmit signals, said plurality of antenna means coupled to said plurality of receive channel means on a one-for-one basis.

19. A missile scoring system as claimed in claim 18, wherein said means for receiving further includes a plurality of video channel group means for receiving said sampled radar transmit signals and providing a plurality of bits describing the rate of change of said received radar transmit signals, said video channel group means coupled to a corresponding receive channel means on a one-for-one basis.

20. A missile scoring system as claimed in claim 19, wherein each of said video channel group means includes a plurality of video channel means, each of said video channel means providing one-bit indicating a slope of said received radar transmit signals, each of said plurality of video channel means being coupled to said corresponding receive channel means.