Random noise automotive radar system

• US 6,121,915 A
• Filed: 12/03/1997
• Issued: 09/19/2000
• Est. Priority Date: 12/03/1997
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Cooper, George R., Niechayev, Alexander, Huff, Jimmie D.
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US08/982,999
• Time in Patent Office: 1,021 Days
• Field of Search: 342/70, 342/71, 342/72, 342/109, 342/128, 342/145
• US Class Current: 342/70
• CPC Class Codes: G01S 13/18 wherein range gates are used
• CPC Class Codes: G01S 13/26 wherein the transmitted pulses use a frequency- or phase-modulated carrier wave
• CPC Class Codes: G01S 13/32 using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
• CPC Class Codes: G01S 13/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 13/524 based upon the phase or frequency shift resulting from movement of objects, with reference to the transmitted signals, e.g. coherent MTi
• CPC Class Codes: G01S 13/582 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/584 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/64 Velocity measuring systems using range gates
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/9318 Controlling the steering
• CPC Class Codes: G01S 2013/93185 Controlling the brakes
• CPC Class Codes: G01S 2013/9319 Controlling the accelerator
• CPC Class Codes: G01S 2013/9325 for inter-vehicle distance regulation, e.g. navigating in platoons

Abstract

An automotive radar system for use with an automotive control system such as a collision avoidance or smart cruise control system, for example. A wide-bandwidth, random noise signal generated at an RF frequency that is transmitted by a transmitter and reflected from targets in the vicinity of the system. The random noise modulation is sampled prior to transmission in a noise source sampler and this sampled image of the transmitted noise is stored and passed through a series of delay stages that are formed in a correlator. The noise signal reflected from objects is processed by a homodyne receiver and also sampled in a receiver sampler. The noise samples from the signal return are passed to the correlator where they are cross correlated with the delayed images of the transmit noise. The output from the correlator for each unit of delay (range gate) is processed in a digital signal processor to find the range and closing velocity (Doppler frequency) of objects in the field of view. The output (range gate) of the correlator where the delay of the sampled transmit modulation equals the transmit delay of the signal transmitted from the radar system to the object and back, contains the range and closing velocity of the objects. At delays (ranges) where there are no objects to reflect the signal, the outputs of the correlator contain noise. Output signals from the digital signal processor are coupled to the automotive control system which processes the output signals to control the vehicle to avoid collision with the detected targets.

Claims

1. Radar apparatus for use with a vehicle, said apparatus comprising:

a random noise radar system for generating output signals that are indicative of the range and closing velocity of objects detected by the radar system that are in the vicinity of the vehicle, wherein the random noise radar system comprises

a random noise source,

a transmitter coupled to the random noise source for transmitting a random noise signal,

a homodyne receiver,

single bit analog to digital conversion means coupled to the random noise source and to the receiver,

a complex random noise correlator coupled to the single bit analog to digital conversion means for controlling the sampling rate thereof, and for generating a plurality of range gates, and

a digital signal processor coupled to the correlator for cross correlating modulation samples from the signal return with delayed images of the sampled transmit modulation to produce a plurality of range rate output signals that are indicative of the range and closing velocity of detected objects; and

a vehicle control system coupled to the random noise radar system for processing the output signals produced by the radar system to generate control signals that are responsive to the relative range and closing velocity of the objects detected by the radar system.

2. The radar apparatus of claim 1 wherein the vehicle control system processes the output signals from the radar system to activate an alarm.

3. The radar apparatus of claim 1 wherein the transmitter comprises:

a reference noise source at the operating frequency of the system;

a transmit amplifier coupled to the output of the noise source;

a transmit antenna coupled to the output of the transmit amplifier; and

a down converter coupled to the transmit power amplifier.

4. The radar apparatus of claim 1 wherein the homodyne receiver comprises:

a receive antenna;

a limiter-attenuator-amplifier network coupled to the receive antenna; and

a homodyne receiver down converter driven by the local oscillator.

5. The radar apparatus of claim 3 wherein the random noise source is hard limited before being coupled to the second port of the transmitter mixer.

6. The radar apparatus of claim 1 wherein the modulation on the return signal and the transmit modulation are sampled in the analog to digital conversion means at a rate less than or equal to twice the bandwidth of the noise modulation.

7. The radar apparatus of claim 1 wherein the random noise source outputs a continuous random noise signal.

8. The radar apparatus of claim 1 wherein the random noise source outputs a pulsed random noise signal.

9. The radar apparatus of claim 3 wherein the random noise source outputs a noise signal whose spectrum is centered at the desired RF operating frequency, which noise signal is directly coupled into the transmit amplifier.

10. The radar apparatus of claim 1 wherein the vehicle control system processes the output signals from the radar system to control the vehicle to avoid collision with detected objects.

11. Radar apparatus comprising:

a random noise radar system comprising;

a transmitter comprising;

a noise source at the operating frequency of the system;

a transmit amplifier coupled to the output of the noise source;

a transmit antenna coupled to the output of the transmit amplifier; and

a down converter coupled to the transmit power amplifier;

a random noise source coupled to a second port of the transmitter mixer;

a homodyne receiver comprising;

a receive antenna;

a limiter-amplifier-attenuator network coupled to the receive antenna; and

a homodyne receiver down converter driven by the local oscillator;

single bit analog to digital conversion means coupled to the random noise source by way of the down converter;

a complex random noise correlator coupled to the single bit analog to digital conversion means for controlling the sampling rate thereof, and for generating a plurality of range gates; and

a digital signal processor coupled to the correlator for cross correlating modulation samples from the signal return with delayed images of the sampled transmit modulation to produce a plurality of range gate output signals that are indicative of the range and closing velocity of objects detected by the radar system; and

a vehicle control system coupled to the automotive radar system for processing the output signals produced by the radar system to generate a control signal that is responsive to the relative range and closing velocity of objects detected by the radar system.

12. The radar apparatus of claim 11 wherein the vehicle control system processes the output signals from the radar system 10 to activate an alarm.

13. The radar apparatus of claim 11 wherein the random noise source is hard limited before being coupled to the second port of the transmitter mixer.

14. The radar apparatus of claim 11 wherein the modulation on the return signal and the transmit modulation are respectively sampled in the samplers at a rate less than or equal to twice the bandwidth of the noise modulation.

15. The radar apparatus of claim 11 wherein the random noise source outputs a continuous random noise signal.

16. The radar apparatus of claim 11 wherein the random noise source outputs a pulsed random noise signal.

17. The radar apparatus of claim 11 wherein the vehicle control system processes the output signals from the radar system 10 to control the vehicle to avoid collision with detected objects.