Vehicular radar system with self-interference cancellation

• US 9,989,627 B2
• Filed: 10/12/2017
• Issued: 06/05/2018
• Est. Priority Date: 04/25/2016
• Status: Active Grant

• Current Assignee: Uhnder, Inc.
• Original Assignee: Uhnder, Inc.
• Inventors: Eshraghi, Aria, Bordes, Jean P., Davis, Curtis, Rao, Raghunath K., Ali, Murtaza, Dent, Paul W.
• Primary Examiner(s): Bythrow, Peter M
• Application Number:
  US15/782,305
• Publication Number:
  US 20180031675A1
• Time in Patent Office: 236 Days
• CPC Class Codes: G01S 13/347 using more than one modulation frequency
• CPC Class Codes: G01S 13/87 Combinations of radar systems, e.g. primary radar and secondary radar
• CPC Class Codes: G01S 13/931 of land vehicles
• 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 7/0232 Avoidance by frequency multiplex
• CPC Class Codes: G01S 7/0234 Avoidance by code multiplex
• CPC Class Codes: G01S 7/038 Feedthrough nulling circuits
• CPC Class Codes: G01S 7/2813 Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays specially adapted to secondary radar systems G01S13/762; aerials or aerials systems H01Q21/29, H01Q25/00
• CPC Class Codes: G01S 7/292 Extracting wanted echo-signals
• CPC Class Codes: G01S 7/354 Extracting wanted echo-signals Doppler systems G01S13/50
• CPC Class Codes: G01S 7/358 using I/Q processing
• CPC Class Codes: G01S 7/4021 of receivers

Abstract

A radar system is described that comprises a transmitter, a receiver, a spillover cancellation unit, and a combiner. The transmitter transmits radio signals. The receiver receives interfering signals due to local signal coupling of transmitted signals. The local signal coupling comprises at least one interfering path or mechanism. The spillover cancellation unit is configured to output a replica of each of the interfering signals. Each replica is configured to replicate a particular interfering signal received through a particular interfering path or mechanism. The combiner is configured to combine into a signal path of the receiver, a replica of an interfering signal to subtract the interfering signal from the receiver'"'"'s signal path. The receiver receives the transmitted radio signals reflected from objects in the environment without saturating the signal path of the receiver due to the subtraction of the interfering signal from the receiver'"'"'s signal path.

Claims

1. A radar system for a vehicle, the radar system comprising:

a transmitter configured for installation and use on a vehicle, wherein the transmitter is configured to transmit radio signals;

a receiver configured for installation and use on the vehicle, wherein the receiver is configured to receive at least one interfering signal due to local signal coupling of transmitted signals, and wherein the local signal coupling comprises at least one interfering path or mechanism;

a spillover cancellation unit configured to output a replica of each of the at least one interfering signal, wherein each replica is configured to replicate a particular interfering signal received through a particular interfering path or mechanism;

a combiner configured to combine into a signal path of the receiver the replica of each of the at least one interfering signal from which interference is to be suppressed to subtract the at least one interfering signal from the receiver'"'"'s signal path; and

wherein the receiver receives the transmitted radio signals reflected from objects in the environment without saturating the signal path of the receiver due to the subtraction of the at least one interfering signal from the receiver'"'"'s signal path.

2. The radar system of claim 1, wherein the transmitter and receiver are configured to operate simultaneously in a same frequency spectrum during an operational period.

3. The radar system of claim 1, wherein the transmitter is configured to transmit digitally modulated radio signals.

4. The radar system of claim 3, wherein the digitally modulated radio signal is frequency modulated with digital code sequences.

5. The radar system of claim 4, wherein the spillover cancellation unit comprises a digital modulator configured to output a delayed, amplitude weighted, and phase-changed replica of each of the at least one interfering signal, and wherein a particular delayed, amplitude weighted, and phase-changed signal replicates a particular interfering signal received through a particular interfering path or mechanism.

6. The radar system of claim 5, wherein the transmitter is configured to be digitally modulated by a bit stream by means of a first waveform memory addressed by bits of the bit stream, and wherein the modulator comprises a second waveform memory addressed with the same bits of the same bit stream, and wherein the second waveform memory is configured to create the particular delayed, amplitude weighted, and phase-changed replica of the particular interfering signal as received through the particular interfering path or mechanism.

7. The radar system of claim 5, wherein the digital modulator is a replica of a digital modulator of the transmitter from which interference is to be suppressed.

8. The radar system of claim 5, wherein the transmitter is configured to be digitally modulated by a bit stream by means of a first waveform memory addressed by bits of the bit stream, and wherein the modulator comprises a second waveform memory addressed with the same bits of the same bit stream, and wherein the second waveform memory is configured to create the delayed, amplitude weighted, and phase changed replica of the interfering signal as received through the particular interfering path or mechanism.

9. The radar system of claim 5 comprising a re-addition combiner configured to re-add into a later point of the receiver'"'"'s signal path a signal constructed that at least in part adds back the interference which was subtracted earlier in the receiver'"'"'s signal path.

10. The radar system of claim 9, wherein the re-addition combiner is configured to add the interference into the signal path in the digital domain so that the spillover cancellation in the digital signal processing domain will remove the spillover components.

11. The radar system of claim 1 comprising a re-addition combiner configured to re-add into a later point of the receiver'"'"'s signal path a signal constructed that at least in part adds back the interference which was subtracted earlier in the receiver'"'"'s signal path.

12. The radar system of claim 1 comprising one or more semiconductor chips attached to a printed circuit board comprising printed antennas and installed in the vehicle, the at least one interfering path comprising at least one of (i) an on-chip or chip-to-chip transmitter to receiver coupling path, (ii) a transmitter antenna to receiver antenna coupling path, and (iii) a reflective path that reflects a signal transmitted by a transmitter antenna from a nearby part of the receiver to the receiver antenna.

13. The radar system of claim 1, wherein the combiner is located at a point in the receive signal path prior to a down-converter configured to down-convert the radar frequency to an intermediate frequency or to a complex (I, Q) baseband.

14. A continuous wave, multiple-input, multiple-output (MIMO) radar system for use on a vehicle, the MIMO radar system comprising:

a plurality of transmitters configured for installation and use on a vehicle, and configured to transmit radio signals;

a plurality of receivers configured for installation and use on the vehicle, wherein a first receiver of the plurality of receivers receives interfering signals via local signal coupling of transmitted signals, and wherein the local signal coupling comprises a plurality of interfering paths or mechanisms;

a spillover cancellation unit configured to output a replica of each interfering signal, wherein a particular replica replicates a particular interfering signal received by the first receiver via a particular interfering path or mechanism;

a plurality of combiners, wherein a first combiner of the plurality of combiners is configured to combine into a signal path of the first receiver each replica of the interfering signals to subtract the interfering signals from the signal path of the first receiver; and

wherein the first receiver is configured to receive transmitted radio signals reflected from objects in the environment without saturating the signal path of the first receiver due to the subtraction of the interfering signals from the signal path of the first receiver.

15. The radar system of claim 14, wherein the plurality of transmitters is configured to transmit digitally modulated radio signals.

16. The radar system of claim 15, wherein the digitally modulated radio signals are frequency modulated with digital code sequences.

17. The radar system of claim 15, wherein the spillover cancellation unit comprises a digital modulator configured to output a delayed, amplitude weighted, and phase-changed replica of each interfering signal, and wherein a particular delayed, amplitude weighted, and phase-changed signal replicates a particular interfering signal received through a particular interfering path or mechanism.

18. The radar system of claim 14 comprising second combiners associated with the spillover cancellation unit, wherein the second combiners are configured to combine back into respective signal paths of the plurality of receivers, at a point after respective down-converters and analog-to-digital converters down-convert and digitize the received signals, signals that correspond to the signals subtracted by the first combiners.

19. The radar system of claim 14, wherein the local signal coupling comprises components of different delays due to one or more of on-chip transmit-receive coupling, antenna-to-antenna transmit-receive coupling, and transmit-receive coupling due to reflections of transmitted signals from a nearby part of the radar system, and wherein a replica of an interfering signal approximates the sum of all of the components of the different delays.

20. A method for preventing receivers of a radar system from being saturated by local spillover from transmitters of the radar system, the method comprising:

providing a transmitter for installation and use on a vehicle, wherein the transmitter is configured to transmit radio signals;

providing a receiver configured for installation and use on the vehicle, wherein the receiver is configured to receive interfering signals due to local signal coupling of transmitted signals, and wherein the local signal coupling comprises a plurality of interfering paths or mechanisms;

replicating the interfering signals, wherein replicating the interfering signals comprises producing a replica of each interfering signal as received via their respective particular paths or mechanisms;

combining the replicas into a signal path of the receiver, wherein combining the replicas into the signal path of the receiver subtracts the corresponding interfering signals from the signal path of the receiver; and

receiving with the receiver, transmitted radio signals reflected from objects in the environment without saturating the signal path of the receiver due to the subtraction of the interfering signals from the signal path of the receiver.

21. The method of claim 20, wherein the transmitter is configured to transmit digitally modulated radio signals.

22. The method of claim 21, wherein replicating the interfering signals comprises producing a delayed, amplitude weighted, and phase shifted replica of each interfering signal, and wherein a particular delayed, amplitude weighted, and phase-changed signal replicates a particular interfering signal received through a particular interfering path or mechanism.

23. The method of claim 20 comprising recombining back into the signal path of the receiver, at a later point, a signal constructed that at least in part adds back the interference which was subtracted earlier in the receiver'"'"'s signal path.

24. The method of claim 20, wherein the local signal coupling comprises components of different delays due to one or more of on-chip transmit-receive coupling, antenna-to-antenna transmit-receive coupling, and transmit-receive coupling due to reflections of transmitted signals from a nearby part of the radar system, and wherein a replica of an interfering signal approximates the sum of all of the components of the different delays.