Radar I-Q mismatching measurement and calibration

Patent metadata

Field	Value
Publication number	US-10527713-B2
Application number	US-201715450549-A
Country	US
Kind code	B2
Filing date	Mar 6, 2017
Priority date	Mar 6, 2017
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

A method of calibrating a radar system of a vehicle is disclosed. A source signal is transmitted from a transmitter at a target at a selected location from the radar system. An echo signal is received as a reflection of the source signal from the target at an in-phase channel and quadrature channel of a receiver. A range space for the echo signal is obtained that includes a target peak corresponding to the target, wherein the range space includes a ghost peak for the target resulting from an IQ difference between the in-phase and quadrature channels. The IQ difference between the in-phase and quadrature channels is adjusted to reduce an amplitude of the ghost frequency peak.

First claim

What is claimed is:

1. A method of calibrating a radar system, comprising:
generating a reference signal related to a source signal transmitted, from a transmitter, the reference signal having an in-phase reference component and a quadrature reference component;
receiving an echo signal as a reflection of the source signal from a target at a selected location, the echo signal having an in-phase echo component and a quadrature echo component;
combining the in-phase reference signal with the in-phrase echo signal at an in-phase channel of the receiver;
combining the quadrature reference signal with the quadrature echo signal at a quadrature channel of the receiver;
obtaining a range space for the echo signal that includes a target peak corresponding to the target, wherein the range space includes a ghost peak for the target resulting from an IQ difference between the in-phase channel and the quadrature channel; and
adjusting the IQ difference between the in-phase reference signal and the quadrature reference signal to reduce an amplitude of the ghost frequency peak.

2. The method of claim 1 , further comprising estimating a difference in an intensity of the target peak and an intensity of the ghost peak, and adjusting the IQ difference to increase the difference in intensities.

3. The method of claim 1 , wherein an IQ corrector circuit receives the in-phase reference signal and the quadrature reference signal and provides the IQ difference between the in-phase reference signal and the quadrature reference signal.

4. The method of claim 3 , further comprising adjusting the IQ difference at the IQ corrector circuit.

5. The method of claim 1 , wherein the IQ difference is at least one of: (i) a difference between a phase of the in-phase channel and the quadrature channel; and (ii) a difference between a gain of the in-phase channel and a gain of the quadrature channel.

6. The method of claim 1 , wherein a range of the target is within a maximum range of the radar system.

7. The method of claim 1 , further comprising determining one of a range and a Doppler frequency of an object using the calibrated radar system and providing the one of the range and the Doppler frequency to an autonomous driving system of a vehicle in order to provide a signal that the autonomous driving system uses to maneuver the vehicle with respect to the target.

8. A radar system, comprising:
a transmitter circuit that transmits a source signal and a related reference signal, the reference signal having an in-phase reference component and a quadrature reference component;
a receiver circuit for receiving an echo signal that is a reflection of the source signal from a target, wherein the receiver circuit receives an in-phase echo component of the echo signal at an in-phase channel and a quadrature echo component of the echo signal at a quadrature channel;
an IQ corrector circuit that provides an IQ difference between the in-phase reference signal and the quadrature reference signal;
a digital signal processor for obtaining a range space for the echo signal that includes a target peak corresponding to the target, wherein the range space includes a ghost peak resulting from the IQ difference between the in-phase and quadrature channels; and
a correction module that adjusts the IQ difference between the in-phase reference signal and the quadrature reference signal at the IQ corrector circuit to reduce an amplitude of the ghost peak.

9. The radar system of claim 8 , wherein the correction module further estimates a difference in an intensity of the target peak and an intensity of the ghost peak, and adjusts the IQ difference to increase the difference in intensities.

10. The radar system of claim 8 , wherein the IQ corrector circuit receives the in-phase reference signal and the quadrature reference signal from the transmitter circuit.

11. The radar system of claim 8 , wherein the IQ difference is at least one of: (i) a difference between a phase of the in-phase channel and the quadrature channel; and (ii) a difference between a gain of the in-phase channel and a gain of the quadrature channel.

12. The radar system of claim 8 , wherein the selected location of the target is within a maximal range of the radar system.

13. The radar system of claim 8 , wherein the digital signal processor provides at least one of a range and a Doppler frequency of an object using the calibrated radar system and providing the at least one of the range and the Doppler frequency to an autonomous driving system of a vehicle in order to provide a signal that the autonomous driving system uses to maneuver the vehicle with respect to the target.

14. A vehicle, comprising:
a radar system including:
a transmitter circuit that transmits a source signal and a related reference signal, the reference signal having an in-phase reference component and a quadrature reference component;
a receiver circuit for receiving a reflection of the source signal from the target, wherein the receiver circuit receives an in-phase echo component of the echo signal at an in-phase channel and a quadrature echo component of the echo signal at a quadrature channel,
an IQ corrector circuit that provides an IQ difference between the in-phase reference signal and the quadrature reference signal,
a digital signal processor for obtaining a range space for the echo signal that includes a target peak corresponding to the target, wherein the range space includes a ghost peak resulting from the IQ difference between the in-phase and quadrature channels,
a correction module that adjusts the IQ difference between the in-phase reference signal and the quadrature reference signal at the IQ corrector circuit to reduce an amplitude of the ghost peak, and
a driving system of the vehicle that maneuvers with respect to an object detected using the radar system, wherein the calibration of the radar system increases an accuracy of a radar signal obtained using the radar system.

15. The vehicle of claim 14 , wherein the correction module further estimates a difference in an intensity of the target peak and an intensity of the ghost peak, and adjusts the IQ difference to increase the difference in intensities.

16. The vehicle of claim 14 , wherein the IQ corrector circuit receives the in-phase reference signal and the quadrature reference signal from the transmitter circuit.

17. The vehicle of claim 14 , wherein the IQ difference is at least one of: (i) a difference between a phase of the in-phase channel and the quadrature channel; and (ii) a difference between a gain of the in-phase channel and a gain of the quadrature channel.

18. The vehicle of claim 14 , wherein the selected location of the target is within a maximal range of the radar system.

19. The vehicle of claim 14 , wherein the digital signal processor provides at least one of a range and a Doppler frequency of an object using the calibrated radar system and providing the at least one of the range and the Doppler frequency to an autonomous driving system of a vehicle in order to provide a signal that the autonomous driving system uses to maneuver the vehicle with respect to the target.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Bilik Igal
• Pokrass Alexander
• Villeval Shahar

Classifications

• G01S7/4004 Primary

  of parts of a radar system · CPC title

• G01S13/931

  of land vehicles · CPC title

• G01S7/4021 Primary

  of receivers · CPC title

• G01S13/58

  Velocity or trajectory determination systems; Sense-of-movement determination systems · CPC title

• G01S13/32

  using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated · CPC title