Two-step return calibration for lidar cross-talk mitigation

Patent metadata

Field	Value
Publication number	US-12372627-B2
Application number	US-202117644994-A
Country	US
Kind code	B2
Filing date	Dec 17, 2021
Priority date	Dec 17, 2021
Publication date	Jul 29, 2025
Grant date	Jul 29, 2025

Abstract

An optical receiver includes a plurality of photodetectors, a shared memory, and a pulse calibration processing unit communicatively coupled to the shared memory. The optical receiver also includes a hardware accelerator module configured to accept input waveforms from the plurality of photodetectors and compare an amplitude of the respective input waveforms with a predetermined threshold. Based on the comparison, the hardware accelerator module could determine subsets of the input waveforms and determine information indicative of characteristic aspects of the subsets of the input waveforms. The optical receiver is additionally operable to store the determined information in the shared memory and trigger an interrupt for the pulse calibration processing unit to initiate a pulse calibration process on the determined information.

First claim

What is claimed is:

1. An optical receiver comprising:
a plurality of photodetectors;
a shared memory;
a pulse calibration processing unit communicatively coupled to the shared memory; and
a hardware accelerator module configured to:
during an initial phase:
accept input waveforms from the plurality of photodetectors;
compare an amplitude of the respective input waveforms with a predetermined threshold; and
based on the comparison, determine subsets of the input waveforms; and

during a subsequent phase:
determine information indicative of characteristic aspects of the subsets of the input waveforms;
store the determined information in the shared memory; and
trigger an interrupt for the pulse calibration processing unit to initiate a pulse calibration process on the determined information.

2. The optical receiver of claim 1 , wherein the characteristic aspects comprise at least one of:
a pulse integral, a pulse width, a maximum amplitude, a number of extrema, or a location of extrema.

3. The optical receiver of claim 1 , wherein storing the determined information in the shared memory comprises performing a direct memory access procedure to store the determined information in the shared memory.

4. The optical receiver of claim 1 , further comprising:
a plurality of optical channels associated with an application-specific integrated circuit (ASIC) and a shot planning processing unit, wherein each optical channel is associated with:
a hardware accelerator; and
a pulse calibration processing unit.

5. The optical receiver of claim 4 , wherein the shot planning processing unit is configured to:
analyze the characteristic aspects of the subsets of the input waveforms; and
send the characteristic aspects of the subsets of the input waveforms to a binary classifier configured to determine whether the input waveforms are excessively bright.

6. The optical receiver of claim 5 , wherein the shot planning processing unit is configured to:
in response to an indication that the input waveforms are excessively bright, initiate a crosstalk mitigation process in the respective optical channels.

7. The optical receiver of claim 6 , wherein the crosstalk mitigation process comprises turning off at least one light-emitter device associated with the respective optical channels.

8. The optical receiver of claim 7 , wherein the crosstalk mitigation process comprises subsequently turning on at least one light-emitter device after at least one of: a predetermined elapsed time or a lack of crosstalk returns in the respective optical channel.

9. A method comprising:
during an initial phase:
receiving, at a hardware accelerator module, input waveforms from a plurality of photodetectors;
comparing an amplitude of the respective input waveforms with a predetermined threshold; and
based on the comparison, determining subsets of the input waveforms; and

during a subsequent phase:
determining information indicative of characteristic aspects of the subsets of the input waveforms;
storing the determined information in a shared memory; and
triggering an interrupt for a pulse calibration processing unit to initiate a pulse calibration process on the determined information.

10. The method of claim 9 , wherein the characteristic aspects comprise at least one of: a pulse integral, a pulse width, a maximum amplitude, a number of extrema, or a location of extrema.

11. The method of claim 9 , wherein storing the determined information in the shared memory comprises performing a direct memory access procedure to store the determined information in the shared memory.

12. The method of claim 9 , further comprising:
analyzing, at a shot planning processing unit, the characteristic aspects of the subsets of the input waveforms; and
sending the characteristic aspects of the subsets of the input waveforms to a binary classifier configured to determine whether the input waveforms are excessively bright.

13. The method of claim 12 , further comprising:
in response to an indication that the input waveforms are excessively bright, initiating a crosstalk mitigation process in respective optical channels.

14. The method of claim 13 , wherein the crosstalk mitigation process comprises turning off at least one light-emitter device associated with the respective optical channels.

15. The method of claim 14 , wherein the crosstalk mitigation process further comprises subsequently turning on at least one light-emitter device after at least one of: a predetermined elapsed time or a lack of crosstalk returns in the respective optical channel.

16. A non-transitory computer-readable medium having encoded thereon instructions executable to carry out operations, the operations comprising:
during an initial phase:
receiving, at a hardware accelerator module, input waveforms from a plurality of photodetectors;
comparing an amplitude of the respective input waveforms with a predetermined threshold; and
based on the comparison, determining subsets of the input waveforms; and

during a subsequent phase:
determining information indicative of characteristic aspects of the subsets of the input waveforms;
storing the determined information in a shared memory; and
triggering an interrupt for a pulse calibration processing unit to initiate a pulse calibration process on the determined information.

17. The non-transitory computer-readable medium of claim 16 , wherein the characteristic aspects comprise at least one of: a pulse integral, a pulse width, a maximum amplitude, a number of extrema, or a location of extrema.

18. The non-transitory computer-readable medium of claim 16 , wherein storing the determined information in the shared memory comprises performing a direct memory access procedure to store the determined information in the shared memory.

19. The non-transitory computer-readable medium of claim 16 , further comprising:
analyzing, at a shot planning processing unit, the characteristic aspects of the subsets of the input waveforms; and
sending the characteristic aspects of the subsets of the input waveforms to a binary classifier configured to determine whether the input waveforms are excessively bright.

20. The non-transitory computer-readable medium of claim 19 , further comprising:
in response to an indication that the input waveforms are excessively bright, initiating a crosstalk mitigation process in respective optical channels.

Assignees

• Waymo Llc

Inventors

• Kapsenberg Pieter
• Goetz Georges

Classifications

• H04B10/697

  Arrangements for reducing noise and distortion · CPC title

• G01S17/931

  of land vehicles · CPC title

• G01S7/4865

  Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487) · CPC title

• G01S7/497

  Means for monitoring or calibrating · CPC title

• G01S7/4868

  Controlling received signal intensity or exposure of sensor · CPC title