Doppler-based traffic radar system

• US 6,417,796 B1
• Filed: 04/30/2001
• Issued: 07/09/2002
• Est. Priority Date: 09/16/1998
• Status: Expired due to Term

• Current Assignee: MPH Industries, Inc. (MPD Incorporated)
• Original Assignee: MPH Industries, Inc. (MPD Incorporated)
• Inventors: Bowlds, Harvey F.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US09/845,706
• Time in Patent Office: 435 Days
• Field of Search: 342/104, 342/114, 342/115, 342/116, 342/189, 342/192, 342/195, 342/196
• US Class Current: 342/104
• CPC Class Codes: G01S 13/583 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets
• CPC Class Codes: G01S 13/92 for velocity measurement
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: G01S 7/35 Details of non-pulse systems

Abstract

A Doppler-based radar system and related method are provided for determining the direction and speed of at least one selected target traveling in the same lane as a moving patrol vehicle supporting the radar system independent of the direction of the target relative to the platform. The radar system includes an oscillator to generate a signal, an antenna to transmit the signal toward the at least one target and to receive a return signal reflected from the at least one target, a turnstile in communication with the antenna for receiving the return signal and forming processing signals which are different in phase, and circuitry for determining the direction of the at least one target relative to the platform. In particular, samples of the processing signals are transformed into the frequency domain and cross-correlated forming cross-correlation components. The radar system selects a target from the imaginary cross-correlation components dependent upon a mode of operation of the radar system and calculates the speed of the at least one target dependent upon a determined direction of the target and displays the speed for the operator'"'"'s use. Advantageously, the radar system and method of operation allow the speed of the at least one target to be monitored without manual assistance from the operator.

Claims

1. A method for determining the speed of a selected moving target traveling in generally the same direction as a moving platform supporting a Doppler-based radar system and independent of the direction of the target relative to the platform comprising the steps of:

transmitting a signal from the platform toward at least one target;

receiving a return signal reflected from the at least one target, said return signal indicative of the speed of the at least one target including the platform;

forming a test processing signal and a reference processing signal such that said processing signals are different in phase;

transforming samples of said test and said reference processing signals into the frequency domain to provide at least one spectrum including a plurality of bins indicative of Doppler components of the at least one target;

cross-correlating said Doppler components to provide a cross-correlation spectrum;

selecting the moving target from said cross-correlation spectrum dependent upon a mode of operation of the radar system;

determining a direction of the at least one target relative to the platform;

calculating the speed of the selected moving target dependent upon the direction of the target; and

displaying the speed of the selected moving target,

whereby the speed of the selected moving target is determined independent of the relative direction of the target to the platform and of operator intervention.

2. The method as claimed in claim 1, wherein said cross-correlation spectrum includes real and imaginary cross-correlated components;

and

wherein the step of determining the direction of the at least one target relative to the platform includes the step of analyzing said imaginary cross-correlated components, said imaginary components being positive when the at least one target is approaching the platform and negative when the at least one target is receding from the platform.

3. The method as claimed in claim 2, wherein the step of transforming samples of said test and said reference processing signals into the frequency domain includes the steps of performing a first fast fourier transform on said samples of said test processing signal to provide a test spectrum including a plurality of bins indicative of Doppler components of the at least one target;

and

performing a second fast fourier transform on said samples of said reference processing signal to provide a reference spectrum including a plurality of bins indicative of Doppler components of the at least one target.

4. The method as claimed in claim 2, wherein the step of transforming samples of said test and said reference processing signals into the frequency domain includes the steps of performing a complex fast fourier transform using one of either said test samples or said reference samples as real inputs and a remaining said test samples or said reference samples as imaginary inputs to provide a spectrum including a plurality of bins indicative of Doppler components of the at least one target.

5. The method as claimed in claim 1, further comprising the step of windowing said samples of said test and said reference processing signals.

6. A method for determining the speed of a selected moving target traveling in generally the same direction as a moving platform supporting a Doppler-based radar system and independent of the direction of the target relative to the platform comprising the steps of:

transmitting a signal from the platform toward at least one target;

receiving a return signal reflected from the at least one target, said return signal indicative of the speed of the at least one target including the platform;

forming a test processing signal and a reference processing signal such that said processing signals are different in phase by substantially splitting said return signal into first and second split signals and mixing said first split signal with a first portion of the transmitting signal and said second split signal with a second portion of the transmitting signal, said first and second portions being different in phase;

transforming samples of said test and said reference processing signals into the frequency domain to provide at least one spectrum including a plurality of bins indicative of Doppler components of the at least one target;

cross-correlating said Doppler components to provide a cross-correlation spectrum;

selecting the moving target from said cross-correlation spectrum dependent upon a mode of operation of the radar system;

determining a direction of the at least one target relative to the platform;

calculating the speed of the selected moving target dependent upon the direction of the target; and

displaying the speed of the selected moving target.

7. The method as claimed in claim 6, wherein said cross-correlation spectrum includes real and imaginary cross-correlated components;

and

wherein the step of determining the direction of the at least one target relative to the platform includes the step of analyzing said imaginary cross-correlated components, said imaginary components being positive when the at least one target is approaching the platform and negative when the at least one target is receding from the platform.

8. The method as claimed in claim 7, wherein the step of transforming samples of said test and said reference processing signals into the frequency domain includes the steps of performing a first fast fourier transform on said samples of said test processing signal to provide a test spectrum;

and

performing a second fast fourier transform on said samples of said reference processing signal to provide a reference spectrum.

9. The method as claimed in claim 7, wherein the step of transforming samples of said test and said reference processing signals into the frequency domain includes the steps of performing a complex fast fourier transform using one of either of said test or reference samples as real inputs and the remaining test or reference samples as imaginary inputs to provide a spectrum.

10. The method as claimed in claim 7, wherein said cross-correlation spectrum includes bins indicative of the amplitude and frequency of the at least one target;

and

wherein the step of selecting the moving target from said spectrum includes selecting the at least one target having the largest amplitude or the highest frequency dependent upon a mode of operation of the radar system.

11. A Doppler-based radar system for determining the speed of at least one selected moving target traveling in generally the same direction as a moving platform supporting said radar system and independent of the direction of the target relative to the platform comprising:

an oscillator to generate a signal;

an antenna to transmit said oscillator signal toward the at least one target and to receive a return signal reflected from the at least one target, said return signal indicative of the frequency of the at least one target and the platform;

a turnstile in communication with said antenna for receiving said return signal and forming a test processing signal and a reference processing signal such that said signals are different in phase;

a processor programmed to transform samples of said test processing signal and said reference processing signal into the frequency domain to provide at least one spectrum having a plurality of bins indicative of Doppler components of the at least one target, and to cross-correlate said Doppler components to provide a cross-correlation spectrum including a plurality of bins which are indicative of the relative speed and direction of the at least one target,

whereby the speed of the at least one target may be determined independent of the relative direction of the at least one target to the platform.

12. The radar system of claim 11, wherein said processor is programmed to select the at least one target from said cross-correlation spectrum dependent upon a mode of operation of the radar system, determine a direction of the at least one target, and calculate a speed of the at least one target dependent upon the direction of the target.

13. The radar system of claim 11, wherein said cross-correlation spectrum includes real and imaginary cross-correlated components;

and

wherein said processor is programmed to analyze said imaginary cross-correlated components to determine the direction of the at least one target relative the platform, said imaginary components being positive when the at least one target is approaching the platform and negative when the at least one target is receding from the platform.

14. The radar system of claim 13, wherein said processor transforms said samples of said test and reference processing signals into the frequency domain by performing a first fast fourier transform on said samples of said test processing signal to provide a test spectrum and a second fast fourier transform on said samples of said reference processing signals to provide a reference spectrum.

15. The radar system of claim 13, wherein said processor transforms said samples of said test and reference processing signals into the frequency domain by performing a complex fast fourier transform using one of either of said test samples or said reference samples as real inputs and a remaining said test samples or said reference samples as imaginary inputs to provide a spectrum including a plurality of bins indicative of Doppler components of the at least one target.

16. The radar system of claim 11, further comprising a display, said display for showing the speed of the at least one target.

17. A Doppler-based radar system selectively operable to determine the speed of a moving target traveling in generally the same direction as a platform supporting said radar system and independent of the direction of the target relative to the platform comprising:

an oscillator to generate a signal;

an antenna to transmit said oscillator signal toward at least one target and to receive a return signal reflected from the at least one target, said return signal indicative of the frequency of the at least one target and the platform;

a turnstile in communication with said antenna for receiving said return signal and forming a test processing signal and a reference processing signal such that said signals are different in phase; and

circuitry for determining a direction of the at least one target relative to the platform by transforming samples of said test and reference processing signals into the frequency domain to provide at least one spectrum and cross-correlating components of said at least one spectrum to provide a cross-correlation spectrum, and calculating the speed of a selected target dependent upon a mode of operation of the radar system.

18. The radar system of claim 17 wherein said circuitry includes a processor.

19. The radar system of claim 18, wherein said processor transforms said samples of said test and reference processing signals into the frequency domain by performing a first fast fourier transform on said samples of said test processing signal to provide a test spectrum including a plurality of bins indicative of Doppler components of the at least one target and a second fast fourier transform on said samples of said reference processing signals to provide a reference spectrum including a plurality of bins indicative of Doppler components of the at least one target.

20. The radar system of claim 19, wherein said cross-correlation spectrum includes real and imaginary cross-correlated components;

and

wherein the processor determines the direction of the at least one target relative to the platform by analyzing said imaginary cross-correlated components, said imaginary components being positive when the at least one target is approaching the platform and negative when the at least one target is receding from the platform.

21. The radar system of claim 18, wherein said processor transforms said samples of said test and reference processing signals into the frequency domain by performing a complex fast fourier transform using one of either said test or reference samples as real inputs and the remaining said test or reference samples as imaginary inputs to provide a spectrum including a plurality of bins indicative of Doppler components of the at least one target.

22. The radar system of claim 21, wherein said cross-correlation spectrum includes real and imaginary cross-correlated components;

and

wherein the processor determines the direction of the at least one target relative to the platform by analyzing said imaginary cross-correlated components, said imaginary components being positive when the at least one target is approaching the platform and negative when the at least one target is receding from the platform.

23. A method for determining the speed of at least one moving target traveling in generally the same direction as a platform supporting a Doppler-based radar system and independent of the direction of the at least one target relative to the platform comprising the steps of:

transmitting a signal from the platform toward the at least one target;

receiving a return signal reflected from the at least one target, said return signal indicative of the speed of the at least one target including the platform;

forming a test processing signal and a reference processing signal such that said processing signals are different in phase;

analyzing cross-correlated components of a fourier transform of samples of said test and reference processing signals to determine a direction of the at least one target relative to the platform;

calculating the speed of the at least one target dependent upon the direction of the at least one target; and

displaying the speed of at least one selected target of the at least one target.

24. The method as claimed in claim 23, wherein the step of analyzing cross-correlated components of a fourier transform includes transforming samples of said test and said reference processing signals into the frequency domain to provide at least one spectrum including a plurality of bins indicative of Doppler components of the at least one target;

and

cross-correlating said Doppler components to provide a cross-correlation spectrum including a plurality of bins indicative of Doppler components of the at least one target.

25. The method as claimed in claim 24, wherein the step of transforming samples of said test and said reference processing signals into the frequency domain includes the steps of performing a first fast fourier transform on said samples of said test processing signal to provide a test spectrum;

and

performing a second fast fourier transform on said samples of said reference processing signal to provide a reference spectrum.

26. The method as claimed in claim 24, wherein the step of transforming samples of said test and said reference processing signals into the frequency domain includes the steps of performing a complex fast fourier transform using one of either said test samples or said reference samples as real inputs and a remaining said test samples or said reference samples as imaginary inputs to provide a spectrum including a plurality of bins indicative of Doppler components of the at least one target.

27. A method for determining the speed of a selected moving target from a stationary platform supporting a Doppler-based radar system comprising the steps of:

transmitting a signal from the platform toward at least one target;

receiving a return signal reflected from the at least one target, said return signal indicative of the speed of the at least one target;

forming a test processing signal and a reference processing signal such that said processing signals are different in phase;

transforming samples of said test and said reference processing signals into the frequency domain to provide at least one spectrum including a plurality of bins indicative of Doppler components of the at least one target;

cross-correlating said Doppler components to provide a cross-correlation spectrum;

selecting the moving target from said cross-correlation spectrum dependent upon a mode of operation of the radar system;

calculating and displaying the speed of the selected moving target,

whereby all approaching or receding targets of said at least one target are selectively eliminated from consideration in the selecting step dependent upon said mode of operation of the radar system.

28. The method as claimed in claim 27, wherein said cross-correlation spectrum includes real and imaginary cross-correlated components;

and

wherein the step of selecting the moving target from said cross-correlation spectrum includes the step of analyzing said imaginary cross-correlated components, said imaginary components being positive when the at least one target is approaching the platform and negative when the at least one target is receding from the platform.

29. The method as claimed in claim 27, wherein the step of transforming samples of said test and said reference processing signals into the frequency domain includes the steps of performing a first fast fourier transform on said samples of said test processing signal to provide a test spectrum including a plurality of bins indicative of Doppler components of the at least one target;

and

performing a second fast fourier transform on said samples of said reference processing signal to provide a reference spectrum including a plurality of bins indicative of Doppler components of the at least one target.

30. The method as claimed in claim 27, wherein the step of transforming samples of said test and said reference processing signals into the frequency domain includes the steps of performing a complex fast fourier transform using one of either said test samples or said reference samples as real inputs and a remaining said test samples or said reference samples as imaginary inputs to provide a spectrum including a plurality of bins indicative of Doppler components of the at least one target.