Coherent radar detection using non-coherent architecture

• US 6,211,815 B1
• Filed: 03/31/2000
• Issued: 04/03/2001
• Est. Priority Date: 07/25/1997
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Gibson, Timothy, Richey, Manuel
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US09/541,473
• Time in Patent Office: 368 Days
• Field of Search: 342/21, 342/26, 342/89, 342/90, 342/99, 342/100, 342/101, 342/102, 342/103, 342/189, 342/192, 342/194, 342/195, 342/196
• US Class Current: 342/194
• CPC Class Codes: G01S 7/285 Receivers
• CPC Class Codes: G01S 7/2886 using I/Q processing
• CPC Class Codes: H02M 3/285 Single converters with a plurality of output stages connected in parallel parallel operation of a plurality of converters in dc distribution networks H02J1/10

Abstract

In a radar system having a transmitter that produces pulses to be radiated by an antenna and a receiver that detects target information, complex demodulation is performed on an attenuated and limited waveform of the transmitter produced pulse. A matched filter is generated responsive to the complex demodulated waveform that is a time reversed conjugate image of the waveform corresponding to the produced pulse. Complex demodulation is performed on the return signal received by the receiver corresponding the produced pulse and the complex demodulated return signal is correlated with the matched filter that corresponds to the time reversed conjugate image of the waveform of the produced pulse.

Claims

1. A receiver in a radar system having a transmitter for producing pulses to be radiated by an antenna, the receiver comprising:

means responsive to a transmitter produced pulse for performing complex demodulation of a waveform corresponding to the produced pulse;

means responsive to the complex demodulated waveform corresponding to the produced pulse for forming a filter representative of the pulses produced by the transmitter;

means for receiving a return signal corresponding to each pulse produced by the transmitter from the antenna;

means for performing complex demodulation of the return signal; and

means for correlating the complex demodulated return signal with the filter representative of the pulses produced by the transmitter.

2. A receiver in a radar system according to claim 1, wherein a filter is formed for each pulse produced by the transmitter and the correlating means correlates the complex demodulated return signal with the filter formed for the pulse corresponding to the return signal.

3. A receiver in a radar system according to claim 1, wherein the filter formed in response to the complex demodulated waveform of the produced pulse comprises a matched filter.

4. A receiver in a radar system according to claim 3, wherein the matched filter comprises a time reversed conjugate image of the waveform corresponding to the produced pulse.

5. A receiver in a radar system according to claim 1, further comprising means for delaying performing complex demodulation of the waveform corresponding to the produced pulse at least for a time corresponding to a width of the produced pulse.

6. A receiver in a radar system according to claim 1, wherein the means responsive to the transmitter produced pulses for performing complex demodulation of a waveform corresponding to the produced pulse comprises means coupled between the transmitter and the receiver for attenuating and limiting the produced pulse.

7. A receiver in a radar system according to claim 1, wherein the transmitter is coupled to the receiver through a circulator, an attenuator and a limiter during the pulse produced by the transmitter.

8. A receiver in a radar system according to claim 1, wherein the antenna is coupled to the receiver through a circulator and a limiter after termination of the pulse produced by the transmitter.

9. A receiver in a radar system according to claim 1, further comprising:

means responsive the formed transmission pulse representative filter for generating a signal representing an average frequency of coefficients of central samples of the transmission pulse representative filter;

means responsive the correlated complex demodulated return signal for forming a signal representing an average frequency of peak centered samples of the correlated complex demodulated return signal; and

means responsive to the average frequency of the peak centered samples of the correlated complex demodulated return signal and the average frequency of the coefficients of central samples of the transmission pulse representative filter for generating a Doppler shift indicator.

10. A method of detecting a target in a radar receiver of a radar system having a transmitter producing pulses for radiation by an antenna, the method comprising the steps of:

performing a complex demodulation of a waveform corresponding to the pulse produced by the transmitter in the receiver;

forming a filter representative of the pulse produced by the transmitter responsive to the complex demodulated waveform in the receiver;

receiving a return signal corresponding to each pulse produced by the transmitter from the antenna;

performing complex demodulation of the return signal; and

correlating the complex demodulated return signal with the filter representative of the pulses produced by the transmitter.

11. A method according to claim 10, wherein the filter forming step includes forming a filter for each pulse produced by the transmitter and the correlating step includes correlating the complex demodulated return signal with the filter formed for the pulse corresponding to the return signal.

12. A method according to claim 10, wherein the filter formed in response to the complex demodulated waveform corresponding to the produced pulse comprises a matched filter.

13. A method according to claim 12, wherein the matched filter comprises a time reversed conjugate image of the waveform corresponding to the produced pulse.

14. A method according to claim 10, further comprising the step of delaying performing complex demodulation of the waveform corresponding to the pulse produced by the transmitter at least for a time corresponding to a width of the produced pulse.

15. A method according to claim 10, wherein the step of performing complex demodulation of the waveform corresponding to the produced pulse includes attenuating and limiting the produced pulse from the transmitter to limit the waveform for complex demodulation.

16. A method according to claim 10, wherein the transmitter is coupled to the receiver through a circulator, an attenuator and a limiter during the pulse produced by the transmitter.

17. A method according to claim 10, wherein the antenna is coupled to the receiver through a circulator and a limiter after a termination of the pulse produced by the transmitter.

18. A method according to claim 10, further comprising the steps of:

generating a signal representing an average frequency of coefficients of central samples of the transmission pulse representative filter responsive the formed transmission pulse representative filter;

forming a signal representing an average frequency of peak centered samples of the correlated complex demodulated return signal responsive the correlated complex demodulated return signal for; and

generating a Doppler shift indicator responsive to the average frequency of the peak centered samples of the correlated complex demodulated return signal and the average frequency of the coefficients of central samples of the transmission pulse representative filter.

19. A radar system comprising:

an antenna;

a transmitter for producing pulses to be radiated by the antenna;

a receiver for detecting target information from return signals responsive to the pulses produced by the transmitter;

in the receiver;

means responsive to the pulses produced by the transmitter for performing complex demodulation of a waveform corresponding to a produced pulses;

means responsive to the complex demodulated waveform corresponding to the produced pulse for forming a filter representative of the pulses produced by the transmitter;

means for receiving a return signal corresponding to each pulse produced by the transmitter from the antenna;

means for performing complex demodulation of the return signal; and

means for correlating the complex demodulated return signal with the filter representative of the pulses produced by the transmitter.

20. A radar system according to claim 19, wherein a filter is formed for each pulse produced by the transmitter and the correlating means correlates the complex demodulated return signal with the filter formed for the pulse corresponding to the return signal.

21. A radar system according to claim 19, wherein the filter formed in response to the complex demodulated waveform comprises a matched filter.

22. A radar system according to claim 21, wherein the matched filter comprises a time reversed conjugate image of the waveform corresponding to the produced pulse.

23. A radar system according to claim 19, wherein the receiver further comprises means for delaying performing complex demodulation of the waveform corresponding to the produced pulse at least for a time corresponding to a width of the produced pulse.

24. A radar system according to claim 19, wherein the means for performing complex demodulation of a waveform corresponding to the produced pulse comprises means coupled between the transmitter and the receiver for attenuating and limiting the produced pulse.

25. A radar system to claim 19, wherein the transmitter is coupled to the receiver through a circulator, an attenuator and a limiter during the pulse produced by the transmitter.

26. A radar system according to claim 19, wherein the antenna is coupled to the receiver through a circulator and a limiter after termination of the pulse produced by the transmitter.

27. A radar system according to claim 19, further comprising:

means responsive the formed transmission pulse representative filter for generating a signal representing an average frequency of coefficients of central samples of the transmission pulse representative filter;

means responsive the correlated complex demodulated return signal for forming a signal representing an average frequency of peak centered samples of the correlated complex demodulated return signal; and

means responsive to the average frequency of the peak centered samples of the correlated complex demodulated return signal and the average frequency of the coefficients of central samples of the transmission pulse representative filter for generating a Doppler shift indicator.

28. In a receiver of a radar system having a transmitter producing pulses for radiation by an antenna, a computer usable medium having computer readable program code units embodied therein comprising:

a first program code unit for performing a complex demodulation of a waveform corresponding to a pulse produced by the transmitter;

a second program code unit for forming a filter representative of the pulses produced by the transmitter responsive to the complex demodulated waveform;

a third program code unit for receiving a return signal corresponding to each pulse produced by the transmitter from the antenna;

a fourth program code unit for performing complex demodulation of the received return signal; and

a fifth program code unit for correlating the complex demodulated return signal with the filter representative of the pulses of produced by the transmitter.

29. In a receiver of a radar system having a transmitter producing pulses for radiation by an antenna, a computer usable medium having computer readable program code units embodied therein according to claim 28, wherein the fourth program code unit comprises a program code unit for forming a filter for each pulse produced by the transmitter and the fifth program code unit comprises a program code unit for correlating the complex demodulated return signal with the filter formed for the pulse corresponding to the return signal.

30. In a receiver of a radar system having a transmitter producing pulses for radiation by an antenna, a computer usable medium having computer readable program code units embodied therein according to claim 28, wherein the filter formed in response to the complex demodulated waveform comprises a matched filter.

31. In a receiver of a radar system having a transmitter producing pulses for radiation by an antenna, a computer usable medium having computer readable program code units embodied therein according to claim 30, wherein the matched filter comprises a time reversed conjugate image of the waveform corresponding to the produced pulse.

32. In a receiver of a radar system having a transmitter producing pulses for radiation by an antenna, a computer usable medium having computer readable program code units embodied therein according to claim 28, further comprising a program code unit for delaying performing complex demodulation of the waveform corresponding to the pulse produced by the transmitter at least for a time corresponding to a width of the produced pulse.

33. In a receiver of a radar system having a transmitter producing pulses for radiation by an antenna, a computer usable medium having computer readable program code units embodied therein according to claim 28, further comprising:

a program code unit for generating a signal representing an average frequency of coefficients of central samples of the transmission pulse representative filter responsive the formed transmission pulse representative filter;

a program code unit for forming a signal representing an average frequency of peak centered samples of the correlated complex demodulated return signal responsive the correlated complex demodulated return signal for; and

a program code unit for generating a Doppler shift indicator responsive to the average frequency of the peak centered samples of the correlated complex demodulated return signal and the average frequency of the coefficients of central samples of the transmission pulse representative filter.

34. A receiver in a radar system having a transmitter for producing pulses to be radiated by an antenna, the receiver comprising:

a signal receiving unit including a coupler for receiving the pulse produced by the transmitter and a coupler for receiving from the antenna a return signal corresponding to each pulse produced by the transmitter;

a signal processor comprising;

a demodulator processing unit responsive to a transmitter produced pulse for performing complex demodulation of a waveform corresponding to the produced pulse;

a filter processing unit responsive to the complex demodulated waveform corresponding to the produced pulse for forming a filter representative of the pulses produced by the transmitter;

a demodulator processing unit for performing complex demodulation of the return signal; and

a correlating processing unit for correlating the complex demodulated return signal with the filter representative of the pulses produced by the transmitter.

35. A receiver in a radar system according to claim 34, wherein the filter processing unit forms a filter for each pulse produced by the transmitter and the correlating processing unit correlates the complex demodulated return signal with the filter formed for the pulse corresponding to the return signal.

36. A receiver in a radar system according to claim 34, wherein the filter formed by the signal processor in response to the complex demodulated waveform of the produced pulse comprises a matched filter.

37. A receiver in a radar system according to claim 36, wherein the matched filter formed by the signal processor comprises a time reversed conjugate image of the waveform corresponding to the produced pulse.

38. A receiver in a radar system according to claim 34, wherein the coupling unit for receiving the pulse produced by the transmitter comprises a delay unit for delaying performing complex demodulation of the waveform corresponding to the produced pulse at least for a time corresponding to a width of the produced pulse.

39. A receiver in a radar system according to claim 34, wherein the coupling unit for receiving the pulse produced by the transmitter comprises a coupling unit responsive to the transmitter produced pulses for attenuating and limiting the produced pulse prior to complex demodulation.

40. A receiver in a radar system according to claim 34, wherein the coupling unit for receiving the pulse produced by the transmitter comprsies a circulator, an attenuator and a limiter operative during the pulse produced by the transmitter.

41. A receiver in a radar system according to claim 34, wherein the coupler for receiving the return signal comprises a circulator and a limiter operative after termination of the pulse produced by the transmitter.

42. A receiver in a radar system according to claim 34, further comprising:

a processing unit responsive the formed transmission pulse representative filter for generating a signal representing an average frequency of coefficients of central samples of the transmission pulse representative filter;

a processing unit responsive the correlated complex demodulated return signal for forming a signal representing an average frequency of peak centered samples of the correlated complex demodulated return signal; and

a processing unit responsive to the average frequency of the peak centered samples of the correlated complex demodulated return signal and the average frequency of the coefficients of central samples of the transmission pulse representative filter for generating a Doppler shift indicator.

43. A radar system comprising:

an antenna;

a transmitter for producing pulses to be radiated by the antenna;

a receiver for detecting target information from return signals responsive to the pulses produced by the transmitter;

in the receiver;

a signal receiving unit including a coupler for coupling the pulse produced by the transmitter to the receiver and a coupler for receving a return signal corresponding to each produced pulse from the antenna; and

a signal processor comprising;

a demodulating processing unit responsive to the pulses produced by the transmitter for performing complex demodulation of a waveform corresponding to a produced pulses;

a filter processing unit responsive to the complex demodulated waveform corresponding to the produced pulse for forming a filter representative of the pulses produced by the transmitter;

a demodulating processing unit for performing complex demodulation of the return signal; and

a correlating processing unit for correlating the complex demodulated return signal with the filter representative of the pulses produced by the transmitter.

44. A radar system according to claim 43, wherein a filter is formed for each pulse produced by the transmitter and the correlating processing unit correlates the complex demodulated return signal with the filter formed for the pulse corresponding to the return signal.

45. A radar system according to claim 43, wherein the filter formed in response to the complex demodulated waveform comprises a matched filter.

46. A radar system according to claim 45, wherein the matched filter comprises a time reversed conjugate image of the waveform corresponding to the produced pulse.

47. A radar system according to claim 43, wherein the receiver further comprises a delay unit for delaying performing complex demodulation of the waveform corresponding to the produced pulse at least for a time corresponding to a width of the produced pulse.

48. A radar system according to claim 43, wherein the the coupler for coupling the pulse produced by the transmitter comprises an attenuating and limiting unit for attenuating and limiting the produced pulse.

49. A radar system to claim 43, wherein the coupler for coupling the produced pulse comprises a circulator, an attenuator and a limiter operative during the pulse produced by the transmitter.

50. A radar system according to claim 43, wherein the coupler for receiving the return pulse comprises a circulator and a limiter operative after termination of the pulse produced by the transmitter.

51. A radar system according to claim 43, further comprising:

a processing unit responsive the formed transmission pulse representative filter for generating a signal representing an average frequency of coefficients of central samples of the transmission pulse representative filter;

a processing unit responsive the correlated complex demodulated return signal for forming a signal representing an average frequency of peak centered samples of the correlated complex demodulated return signal; and

a processing unit responsive to the average frequency of the peak centered samples of the correlated complex demodulated return signal and the average frequency of the coefficients of central samples of the transmission pulse representative filter for generating a Doppler shift indicator.