Radar signal processor

• US 5,508,706 A
• Filed: 12/23/1993
• Issued: 04/16/1996
• Est. Priority Date: 09/30/1991
• Status: Expired due to Fees

• Current Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Shreve, Gregory A., Core, Mark T., Harrison, James G., Moffa, Philip J., Tsou, Hsi-Shen E.
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US08/173,540
• Time in Patent Office: 845 Days
• Field of Search: 342/109, 342/110, 342/114, 342/115, 342/128, 342/175, 342/192, 342/196, 364/724.01
• US Class Current: 342/192
• CPC Class Codes: B60Q 1/0023 the element being a sensor, e.g. distance sensor, camera
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01S 13/345 using triangular modulation
• CPC Class Codes: G01S 13/726 Multiple target tracking
• CPC Class Codes: G01S 13/92 for velocity measurement
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/0263 Passive array antenna
• CPC Class Codes: G01S 2013/9315 Monitoring blind spots
• CPC Class Codes: G01S 2013/9316 combined with communication equipment with other vehicles or with base stations
• CPC Class Codes: G01S 2013/9317 Driving backwards
• CPC Class Codes: G01S 2013/93185 Controlling the brakes
• CPC Class Codes: G01S 2013/9319 Controlling the accelerator
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 2013/9321 Velocity regulation, e.g. cruise control
• CPC Class Codes: G01S 2013/93272 in the back of the vehicles
• CPC Class Codes: G01S 2013/93274 on the side of the vehicles
• CPC Class Codes: G01S 2013/93275 in the bumper area
• CPC Class Codes: G01S 2013/93277 in the lights
• 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 7/0235 Avoidance by time multiplex
• CPC Class Codes: G01S 7/032 : Constructional details for solid-state radar subsystems
• CPC Class Codes: G01S 7/2883 : using FFT processing
• CPC Class Codes: G01S 7/2927 : by deriving and controlling a threshold value
• CPC Class Codes: H01Q 1/3233 : particular used as part of a sensor or in a security system, e.g. for automotive radar, navigation systems
• CPC Class Codes: H01Q 15/0013 : said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective

Abstract

A radar system includes a radar transceiver for generating transmit signals and for receiving signals reflected by targets. The radar system includes a mixer for combining the transmit signals and the reflected signals into a mixer signal. A radar signal processor includes a sampling device, connected to the mixer, for sampling the mixer signal and for generating a sampled mixer signal. A spectrum estimation device, connected to the sampling device, generates a range profile signal including a plurality of range bins each containing a magnitude of a spectral component. A threshold device, connected to the spectrum estimation device, generates a target space array from the range profile signal. A target decision device, connected to the threshold device, generates estimated range and speed signals for a closest target from the target space array.

Claims

1. In a radar system including a radar transceiver means for generating transmit signals and for receiving signals reflected by targets, and a mixer for combining the transmit signals and the reflected signals into a mixer signal, a radar signal processor comprising:

sampling means, connected to said mixer, for sampling the mixer signal and for generating a sampled mixer signal;

spectrum estimation means, connected to said sampling means, for generating a plurality of range profile signals each including a plurality of range bins containing a magnitude of a spectral component;

threshold means, connected to said spectrum estimation means, for generating a target profile signal for each of said plurality of range profile signals and for updating a target space array including a stack of target profile signals by adding a new target profile signal to said stack and by discarding an old target profile signal from said stack; and

target decision means, connected to said threshold means, for generating estimated range and speed signals for a closest target from said target space array.

2. The radar signal processor of claim 1 wherein said spectrum estimation means includes time window means, connected to said sampling means, for generating a windowed signal by multiplying said sampled mixer signal with a time window function to reduce spectral leakage.

3. The radar signal processor of claim 2 wherein said spectrum estimation means further includes generating means, connected to said time window means, for generating a frequency spectrum signal including a series of spectral components.

4. The radar signal processor of claim 3 wherein said generating means uses a fast fourier transform to generate said frequency spectrum signal.

5. The radar signal processor of claim 3 wherein said spectrum estimation means further includes magnitude means, connected to said generating means, for generating a magnitude range profile signal including a plurality of range bins each containing magnitudes of said spectral components.

8. The radar signal processor of claim 1 wherein said threshold means generates a threshold range profile signal including a plurality of range bins and includes a comparing means for comparing said range bins of said threshold range profile signal with range bins of said range profile signal, wherein said threshold means generates target flags for range bins of said range profile signal having a magnitude above a corresponding range bin of said threshold range profile signal.

9. The radar signal processor of claim 8 wherein the magnitude of said range bins of said threshold range profile signal are related to the magnitude of a plurality of adjacent range bins of said range profile signal.

20. The radar signal processor of claim 1 wherein said estimated target range and speed signals are utilized to operate a controlled device.

6. In a radar system including a radar transceiver means for generating transmit signals and for receiving signals reflected by targets, and a mixer for combining the transmit signals and the reflected signals into a mixer signal, a radar signal processor comprising:

sampling means, connected to said mixer, for sampling the mixer signal and for generating a sampled mixer signal;

a spectrum estimator including

time window means, connected to said sampling means, for generating windowed signals by multiplying said sampled mixer signal with a time window function to reduce spectral leakage,

generating means, connected to said time window means, for generating frequency spectrum signals each including a series of spectral components,

magnitude means, connected to said generating means, for generating magnitude range profile signals each including a plurality of range bins containing magnitudes of said spectral components, and

equalization means, connected to said magnitude means, for generating equalized range profile signals each including a plurality of range bins having a noise floor substantially constant with respect to frequency;

threshold means, connected to said spectrum estimator for generating a target space array from said equalized range profile signals; and

target decision means, connected to said threshold means, for generating estimated range and speed signals for a closest target from said target space array.

7. In a radar system including a radar transceiver means for generating transmit signals and for receiving signals reflected by targets, and a mixer for combining the transmit signals and the reflected signals into a mixer signal, a radar signal processor comprising:

sampling means, connected to said mixer, for sampling the mixer signal and for generating a sampled mixer signal;

a spectrum estimator including

time window means, connected to said sampling means, for generating windowed signals by multiplying said sampled mixer signal with a time window function to reduce spectral leakage,

generating means, connected to said time window means, for generating frequency spectrum signals each including a series of spectral components,

magnitude means, connected to said generating means, for generating magnitude range profile signals each including a plurality of range bins containing magnitudes of said spectral components,

equalization means, connected to said magnitude means, for generating equalized range profile signals each including a plurality of range bins having a noise floor substantially constant with respect to frequency, and

averaging means, connected to said equalization means, for integrating a current equalized range profile signal with at least one prior range profile signal to generate an integrated range profile signal and to increase signal to noise ratio thereof;

threshold means, connected to said spectrum estimator for generating a target space array from a plurality of said integrated range profile signals; and

target decision means, connected to said threshold means, for generating estimated range and speed signals for a closest target from said target space array.

10. In a radar system including a radar transceiver means for generating transmit signals and for receiving signals reflected by targets, and a mixer for combining the transmit signals and the reflected signals into a mixer signal, a radar signal processor comprising:

sampling means, connected to said mixer, for sampling the mixer signal and for generating a sampled mixer signal;

spectrum estimation means, connected to said sampling means, for generating a plurality of range profile signals each including a plurality of range bins containing a magnitude of a spectral component;

threshold means, connected to said spectrum estimation means, for generating a target space array from said range profile signals, said threshold means including

averaging means including a moving window for generating an average magnitude by averaging the magnitudes of a plurality of adjacent range bins in said range profile signal,

multiplying means for multiplying said average magnitude by a threshold constant to generate a detection threshold value for one range bin in said threshold range profile signal,

incrementing means for incrementing said moving window, and

control means for repeatedly actuating said averaging means, said multiplying means, and said incrementing means to generate detection threshold values for each range bin of said threshold range profile signal; and

target decision means, connected to said threshold means, for generating estimated range and speed signals for a closest target from said target space array.

11. The radar signal processor of claim 10 wherein said threshold means further includes centroiding means for combining target flags in adjacent range bins and for generating a single target centroid flag in a range bin central to said adjacent range bins.

12. In a radar system including a radar transceiver means for generating transmit signals and for receiving signals reflected by targets, and a mixer for combining the transmit signals and the reflected signals into a mixer signal, a radar signal processor comprising:

sampling means, connected to said mixer, for sampling the mixer signal and for generating a sampled mixer signal;

spectrum estimation means, connected to said sampling means, for generating a plurality of range profile signals each including a plurality of range bins containing a magnitude of a spectral component;

threshold means, connected to said spectrum estimation means, for generating a target space array from said range profile signals; and

target decision means, connected to said threshold means, for generating estimated range and speed signals for a closest target from said target space array, said target decision means including first estimation means for executing an acquisition mode by performing a Hough transform to derive target range and speed for at least one target using said target space array.

13. The radar signal processor of claim 12 wherein said first estimation means further includes histogram means for identifying estimated target range and speed for said at least one target for a said target space array, and wherein said target decision device terminates said acquisition mode and initiates a tracking mode if said estimated target speed correlates to a substantially constant velocity during an acquisition interval.

14. The radar signal processor of claim 13 wherein said target decision means includes second estimation means for executing said tracking mode by performing a Hough transform to derive target range, speed and acceleration for at least one target using said target space array.

15. The radar signal processor of claim 14 wherein said second estimation means further includes histogram means for identifying estimated target range, speed, and acceleration for said at least one target over a plurality of target space arrays.

16. The radar signal processor of claim 15 wherein said second estimation means outputs a tracking signal related to relative probability that said target has said estimated target range, speed, and acceleration to said target decision means.

17. The radar signal processor of claim 16 wherein said target decision means includes hysteresis means for evaluating said tracking signal and for providing hysteresis in a determination to continue said tracking mode or initiate said acquisition mode.

18. The radar signal processor of claim 17 wherein said hysteresis means includes a tracking counter and a comparing means for comparing said tracking signal to a tracking threshold.

19. The radar signal processor of claim 18 wherein said hysteresis means increments said counter when said tracking signal exceeds said tracking threshold, decrements said counter when said tracking signal is less than said tracking threshold, and ends said tracking mode when said tracking counter decreases to zero after being incremented.

23. The radar signal processor of claim 19 further comprising:

beam angle tracking means for tracking said target in azimuth and elevation directions by varying azimuth and elevation angles of said tracking beam to maximize target reflected signals.

24. The radar signal processor of claim 23 further comprising:

sensor means for generating a vehicle steering signal related to changes in vehicle steering direction, wherein said vehicle steering signal is input to said target decision means and said beam angle tracking means to decrease false data generation, clutter and noise.

21. In a radar system including a radar transceiver means for generating transmit signals and for receiving signals reflected by targets, and a mixer for combining the transmit signals and the reflected signals into a mixer signal, a radar signal processor comprising:

sampling means, connected to said mixer, for sampling the mixer signal and for generating a sampled mixer signal;

spectrum estimation means, connected to said sampling means, for generating a plurality of range profile signals each including a plurality of range bins containing a magnitude of a spectral component;

threshold means, connected to said spectrum estimation means, for generating a target space array from said range profile signal; and

target decision means, connected to said threshold means, for generating estimated range and speed signals for a closest target from said target space array, said target decision means utilizing a prior estimated target range and speed to generate an approximated target range and speed for a subsequent sample period and compares the approximated target range and speed with an estimated range and speed for the subsequent sample period to reduce clutter and noise.

22. In a radar system including a radar transceiver means for generating transmit signals and for receiving signals reflected by targets, and a mixer for combining the transmit signals and the reflected signals into a mixer signal, a radar signal processor comprising:

sampling means, connected to said mixer, for sampling the mixer signal and for generating a sampled mixer signal;

spectrum estimation means, connected to said sampling means, for generating a plurality of range profile signals each including a plurality of range bins containing a magnitude of a spectral component;

threshold means, connected to said spectrum estimation means, for generating a target space array from said range profile signal;

target decision means, connected to said threshold means, for generating estimated range and speed signals for a closest target from said target space array; and

gating means for momentarily interrupting power to an antenna connected to said radar transceiver while said radar signal processor computes said estimated target range and speed to reduce environment interference, environmental exposure to radiation, and average transmit power.