SPARSE FREQUENCY WAVEFORM RADAR SYSTEM AND METHOD

• US 20020154054A1
• Filed: 04/18/2001
• Published: 10/24/2002
• Est. Priority Date: 04/18/2001
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Small, James G.
• Granted Patent: US 6,486,827 B2
• Time in Patent Office: Days
• US Class Current: 342/201
• CPC Class Codes: G01S 13/106 using transmission of pulses having some particular characteristics G01S13/12, G01S13/22, G01S13/24, G01S13/26, G01S13/28 and G01S13/30 take precedence
• CPC Class Codes: G01S 13/24 using frequency agility of carrier wave
• CPC Class Codes: G01S 7/28 Details of pulse systems
• CPC Class Codes: G01S 7/36 Means for anti-jamming , e.g. ECCM, i.e. electronic counter-counter measures

Abstract

A radar for locating and tracking objects based on the use of a pulsed waveform, each pulse of the pulsed waveform being made up of a plurality of spectral components having different frequencies, including an antenna. The radar further includes a transmitter operatively coupled to the antenna for generating the plurality of spectral components that make up each pulse of the pulsed waveform and a receiver operatively coupled to the antenna for receiving signals at the frequencies of the plurality of spectral components. The radar also includes a signal processor operatively coupled to the receiver for processing the received signals in order to generate and output a radar presentation and to detect the presence of other signals at particular frequencies, a display operatively coupled to the signal processor for displaying the radar presentation, and finally a controller operatively coupled to the transmitter and the signal processor for varying the frequencies at which the plurality of spectral components are generated, such that the transmitter generates spectral components at frequencies different from the frequencies of other signals detected by the signal processor.

Claims

1. A radar for locating and tracking objects based on the use of a pulsed waveform, each pulse of the pulsed waveform being made up of a plurality of spectral components having different frequencies, comprising:

(a) an antenna;

(b) a transmitter operatively coupled to the antenna for generating the plurality of spectral;

(c) a receiver operatively coupled to the antenna for receiving signals at the frequencies of the plurality of spectral components;

(d) a signal processor operatively coupled to the receiver for processing the received signals in order to generate and output a radar presentation and to detect the presence of other signals at particular frequencies;

(e) a display operatively coupled to the signal processor for displaying the radar presentation; and

(f) a controller operatively coupled to the transmitter and the signal processor for varying the frequencies at which the plurality of spectral components are generated in response to information received from the signal processor, such that the transmitter generates spectral components at frequencies different from the frequencies of other signals detected by the signal processor.

2. A radar according to claim 1, wherein each spectral component is generated at a predetermined frequency.

3. A radar according to claim 2, wherein the controller suppresses the generation of those spectral components having frequencies that are the same as the frequencies of the other signals detected by the signal processor.

4. A radar according to claim 1, wherein the spectral components are produced at frequencies within a predetermined frequency band.

5. A radar according to claim 4, wherein the spectral components are irregularly spaced in terms of frequency across at least a portion of the predetermined frequency band.

6. A radar according to claim 4, wherein the predetermined frequency band is between approximately 20 MHz and approximately 600 MHz.

7. A radar according to claim 1 including a plurality of transmitters and a plurality of receivers, each of the plurality of transmitters for generating one of the plurality of spectral components and each of the plurality of receivers for receiving signals at the frequency one of the plurality of spectral components.

8. A radar according to claim 7, wherein the plurality of transmitters include a master oscillator whereby the spectral components are coherently produced by the plurality of transmitters.

9. A radar according to claim 1, wherein the transmitter is a digital transmitter, which digitally synthesizes each pulse of the pulsed waveform.

10. A radar according to claim 9, wherein the receiver is a direct sampling receiver.

11. A radar according to claim 10, wherein the direct sampling receiver has a sample rate of approximately 1 GS/s.

12. A radar according to claim 1, wherein the antenna is a broadband multiplexing antenna.

13. A radar according to claim 1, wherein the signal processor includes means for generating a received pulsed waveform from the spectral components received by the receiver.

14. A radar according to claim 13, further comprising a recorder for recording each pulse of the pulsed waveform.

15. A radar according to claim 14, wherein the signal processor includes means for correlating the recorded pulsed waveform and the received pulsed waveform in order to generate an impulse response of the radar.

16. A radar according to claim 15, wherein the signal processor uses the impulse response of the radar to generate the radar presentation.

18. A method according to claim 17, wherein the frequencies of the spectral components combined to form the pulse vary from the spectral components combined to form at least one of the plurality of subsequent pulses of the pulsed waveform.

19. A method according to claim 17, wherein the spectral components are generated at irregularly spaced frequencies.

17. A method of generating a pulsed waveform having a plurality of spectral components comprising the steps of:

(a) listening across a predetermined frequency band in order to determine which frequencies within the frequency band are available for transmission;

(b) generating for a finite period of time a plurality of spectral components having frequencies corresponding to at least a portion of the frequencies available for transmission;

(c) combining the plurality of spectral components into a pulse of the pulsed waveform;

(d) transmitting the pulse of the pulsed waveform; and

(e) repeating steps (a)-(e) to generate and transmit a plurality of subsequent pulses of the pulsed waveform.