Radar detection method and apparatus

• US 6,577,269 B2
• Filed: 08/16/2001
• Issued: 06/10/2003
• Est. Priority Date: 08/16/2000
• Status: Expired due to Term

• Current Assignee: Valeo Radar Systems, Inc. (Valeo SE)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Pleva, Joseph S., Woodington, Walter Gordon, Russell, Mark E., Delcheccolo, Michael Joseph, Van Rees, H. Barteld
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): ALSOMIRI, ISAM A
• Application Number:
  US09/930,869
• Publication Number:
  US 20020044082A1
• Time in Patent Office: 663 Days
• Field of Search: 342/70-72, 342/90, 342/95-96, 342/195, 342/196
• US Class Current: 342/196
• CPC Class Codes: B60K 31/0008 including means for detecting potential obstacles in vehicle path
• CPC Class Codes: B60Q 9/008 for anti-collision purposes
• CPC Class Codes: B60T 2201/08 Lane monitoring; Lane Keeping Systems
• CPC Class Codes: B60T 2201/081 using distance control
• CPC Class Codes: B60T 2201/088 using transmission control
• CPC Class Codes: B60W 2530/10 Weight
• CPC Class Codes: B60W 2554/4043 Lateral speed
• CPC Class Codes: B60W 2554/803 Relative lateral speed
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01S 13/282 using a frequency modulated carrier wave G01S13/286 takes precedence
• CPC Class Codes: G01S 13/343 using sawtooth modulation
• CPC Class Codes: G01S 13/346 using noise modulation
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/48 using multiple beams at emission or reception
• CPC Class Codes: G01S 13/584 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/726 Multiple target tracking
• CPC Class Codes: G01S 13/865 Combination of radar systems with lidar systems
• CPC Class Codes: G01S 13/87 Combinations of radar systems, e.g. primary radar and secondary radar
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 13/931 : of land vehicles
• CPC Class Codes: G01S 2013/0245 : Radar with phased array antenna
• CPC Class Codes: G01S 2013/9315 : Monitoring blind spots
• CPC Class Codes: G01S 2013/9321 : Velocity regulation, e.g. cruise control
• CPC Class Codes: G01S 2013/93271 : in the front of the vehicles
• 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 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 7/0232 : Avoidance by frequency multiplex
• CPC Class Codes: G01S 7/032 : Constructional details for solid-state radar subsystems
• CPC Class Codes: G01S 7/038 : Feedthrough nulling circuits
• CPC Class Codes: G01S 7/06 : Cathode-ray tube displays or other two dimensional or three-dimensional displays
• CPC Class Codes: G01S 7/288 : Coherent receivers
• CPC Class Codes: G01S 7/352 : Receivers
• CPC Class Codes: G01S 7/354 : Extracting wanted echo-signals Doppler systems G01S13/50
• CPC Class Codes: G01S 7/356 : involving particularities of FFT processing
• CPC Class Codes: G01S 7/4004 : of parts of a radar system
• CPC Class Codes: G01S 7/4008 : of transmitters
• CPC Class Codes: G01S 7/4021 : of receivers
• 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 1/3258 : using the gutter of the vehicle; Means for clamping a whip aerial on the edge of a part of the vehicle
• CPC Class Codes: H01Q 1/3283 : side-mounted antennas, e.g. bumper-mounted, door-mounted mounted on windscreens H01Q1/1271
• CPC Class Codes: H01Q 1/38 : formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 1/42 : Housings not intimately mechanically associated with radiating elements, e.g. radome
• CPC Class Codes: H01Q 13/10 : Resonant slot antennas
• CPC Class Codes: H01Q 13/18 : the slot being backed by, or formed in boundary wall of, a resonant cavity longitudinally slotted cylinder H01Q13/12 ; Open cavity antennas
• CPC Class Codes: H01Q 21/0043 : Slotted waveguides combination with horns H01Q13/0233
• CPC Class Codes: H01Q 21/0075 : Stripline fed arrays H01Q21/065 takes precedence
• CPC Class Codes: H01Q 21/0087 : Apparatus or processes specially adapted for manufacturing antenna arrays manufacturing waveguides H01P11/00
• CPC Class Codes: H01Q 21/065 : Patch antenna array
• CPC Class Codes: H01Q 25/00 : Antennas or antenna systems providing at least two radiating patterns arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00
• CPC Class Codes: H01Q 3/24 : varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
• CPC Class Codes: H01Q 3/40 : with phasing matrix

Abstract

A radar detection process includes computing a derivative of an FFT output signal to detect an object within a specified detection zone. In one embodiment, a zero crossing in the second derivative of the FFT output signal indicates the presence of an object. The range of the object is determined as a function of the frequency at which the zero crossing occurs. Also described is a detection table containing indicators of the presence or absence of an object within a respective radar beam and processing cycle. At least two such indicators are combined in order to detect the presence of an object within the detection zone.

Claims

1. A method for detecting an object with a radar system comprising:

transmitting a transmit signal;

receiving a receive signal generated by at least a portion of the transmit signal impinging the object;

calculating a difference signal in response to the transmit signal and the receive signal;

performing an FFT on the difference signal to provide an FFT output signal;

computing a derivative of the FFT output signal; and

detecting the object in response to a zero crossing of the derivative of the FFT output signal.

2. The method of claim 1 further comprising the step of detecting a range of the object as a function of a frequency associated with the zero crossing of the derivative of the FFT output signal.

3. The method of claim 2 further comprising:

establishing a range boundary; and

discarding an object detection if the range of the object is outside of the range boundary.

4. The method of claim 1 wherein the transmit signal is an FMCW signal.

5. The method of claim 1 wherein the calculating step comprises calculating a difference between the frequency of the transmit signal and the frequency of the receive signal.

6. The method of claim 1 wherein the derivative is a selected one of a first derivative and a second derivative.

7. The method of claim 1 wherein the zero crossing of the derivative of the FFT output signal is a negative-going zero crossing.

8. A radar system for detecting an object, comprising:

a transmitter for transmitting a transmit signal;

a receiver for receiving a receive signal generated by at least a portion of the transmit signal impinging the object;

a differencing circuit for calculating a difference signal in response to the transmit signal and the receive signal;

an FFT processor for performing an FFT on the difference signal to provide an FFT output signal;

a derivative processor for computing a derivative of the FFT output signal; and

a detector for detecting the object in response to a zero crossing of the derivative of the FFT output signal.

9. The radar system of claim 8 wherein said detector is further operable to detect a range of the object as a function of a frequency associated with the zero crossing of the derivative of the FFT output signal.

10. The radar system of claim 9 further including a comparator for comparing the range of the object to a range boundary and for ignoring detection of the object if the range of the object is outside of the range boundary.

11. The radar system of claim 8 wherein the transmit signal is an FMCW signal.

12. The radar system of claim 8 wherein the differencing circuit calculates a difference between the frequency of the transmit signal and the frequency of the receive signal.

13. The radar system of claim 8 wherein the derivative processor computes one of a first derivative and a second derivative of the FFT output signal.

14. The radar system of claim 8 wherein the detector detects a negative-going zero crossing of the derivative.