Method and system for ladar pulse deconfliction

Patent metadata

Field	Value
Publication number	US-11835658-B2
Application number	US-202117394104-A
Country	US
Kind code	B2
Filing date	Aug 4, 2021
Priority date	Feb 17, 2017
Publication date	Dec 5, 2023
Grant date	Dec 5, 2023

Abstract

Disclosed herein are a number of example embodiments that employ controllable delays between successive ladar pulses in order to discriminate between “own” ladar pulse reflections and “interfering” ladar pulses reflections by a receiver. Example embodiments include designs where a sparse delay sum circuit is used at the receiver and where a funnel filter is used at the receiver. Also, disclosed are techniques for selecting codes to use for the controllable delays as well as techniques for identifying and tracking interfering ladar pulses and their corresponding delay codes. The use of a ladar system with pulse deconfliction is also disclosed as part of an optical data communication system.

First claim

What is claimed is:

1. An apparatus comprising:
a ladar receiver comprising:
a photodetector that senses incoming light and generates a signal representative of the sensed incoming light, wherein the incoming light comprises a combination of an own pulse reflection and noise, wherein the own pulse reflection comprises a plurality of pulses separated by a known delay; and
a signal processing circuit that (1) computes a delay sum signal based on the generated signal and the known delay and (2) detects the own pulse reflection within the generated signal, wherein the signal processing circuit detects the own pulse reflection based on:
a comparison of the delay sum signal with a first threshold;
a comparison that determines whether the generated signal is less than the delay sum signal multiplied by a second threshold; and
a comparison that determines whether the delay sum signal is less than the generated signal multiplied by the second threshold.

2. The apparatus of claim 1 wherein the delay sum signal is based on a doublet pulse separated by the known delay.

3. The apparatus of claim 1 wherein the known delay comprises a first delay and a second delay, wherein the delay sum signal is based on a triplet pulse, wherein a first pulse and a second pulse of the triplet pulse are separated by the first delay, and wherein the second pulse and a third pulse of the triplet pulse are separated by the second delay.

4. The apparatus of claim 3 wherein the first and second delays are different values.

5. The apparatus of claim 1 wherein the known delay comprises a plurality of N−1 delays, and wherein the delay sum signal is based on an N-tuple pulse, wherein the N pulses are separated respectively by the N−1 delays.

6. The apparatus of claim 1 wherein the second threshold is a value greater than 1.

7. The apparatus of claim 1 wherein the first and second thresholds are adjustable.

8. The apparatus of claim 1 wherein the known delay is adjustable.

9. A ladar method comprising:
sensing incoming light, wherein the incoming light comprises a combination of an own pulse reflection and noise, wherein the own pulse reflection comprises a plurality of pulses separated by a known delay;
generating a signal representative of the sensed incoming light;
computing a delay sum signal based on the generated signal and the known delay; and
detecting the own pulse reflection within the generated signal based on (1) a comparison of the delay sum signal with a first threshold, (2) a comparison that determines whether the generated signal is less than the delay sum signal multiplied by a second threshold, and (3) a comparison that determines whether the delay sum signal is less than the generated signal multiplied by the second threshold.

10. The method of claim 9 wherein the delay sum signal is based on a doublet pulse separated by the known delay.

11. The method of claim 9 wherein the known delay comprises a first delay and a second delay, wherein the delay sum signal is based on a triplet pulse, wherein a first pulse and a second pulse of the triplet pulse are separated by the first delay, and wherein the second pulse and a third pulse of the triplet pulse are separated by the second delay.

12. The method of claim 11 wherein the first and second delays are different values.

13. The method of claim 9 wherein the known delay comprises a plurality of N−1 delays, and wherein the delay sum signal is based on an N-tuple pulse, wherein the N pulses are separated respectively by the N−1 delays.

14. The method of claim 9 wherein the second threshold is a value greater than 1.

15. The method of claim 9 further comprising:
adjusting the first threshold and/or the second threshold.

16. The method of claim 9 further comprising:
adjusting the known delay.

17. An apparatus comprising:
a ladar transmitter comprising a plurality of scannable mirrors, wherein the ladar transmitter transmits a plurality of ladar pulses toward a plurality of targets in a field of view via the scannable mirrors, wherein the ladar transmitter is operable to switch between transmitting the ladar pulses via the scannable mirrors in a ladar mode and an optical communication mode, wherein the ladar pulses encode data messages when the ladar transmitter is operating in the optical communication mode;
a ladar receiver that receives and processes reflections of the ladar pulses transmitted by the ladar transmitter when operating in the ladar mode to perform range point measurements with respect to targets that were targeted by the ladar transmitter when operating in the ladar mode;
a memory for storing a data structure that tracks laser dosages delivered by the ladar transmitter to a plurality of different locations in the field of view over time; and
a processor that controls the ladar transmitter when operating in the ladar mode and when operating in the optical communication mode based on the tracked laser dosages from the data structure.

18. The apparatus of claim 17 wherein the data structure comprises a heat map data structure that tracks the laser dosages for the locations in the field of view over a defined time window, wherein the heat map data structure comprises a plurality of data values indexed by azimuth and elevation locations, and wherein the data values represent the tracked laser dosage for the indexed azimuth and elevation locations.

19. The apparatus of claim 17 wherein the processor schedules a plurality of the ladar pulses based on the tracked laser dosages from the data structure.

20. The apparatus of claim 17 wherein the processor controls the ladar transmitter based on the tracked laser dosages from the data structure to avoid transmitting a ladar pulse to a location in the field of view that would cause the tracked laser dosage for that location to exceed a defined threshold.

21. The apparatus of claim 17 wherein the ladar pulses used for the optical communication mode exhibit a different frequency or wavelength than a frequency or wavelength exhibited by the ladar pulses used for the ladar mode.

22. The apparatus of claim 21 wherein the apparatus is arranged as an optical transceiver, the optical transceiver further comprising:
a beam splitter; and
a sensor;
wherein the beam splitter (1) directs incident light that exhibits a frequency or wavelength corresponding to the frequency or wavelength for the ladar mode to the ladar receiver and (2) directs incident light that exhibits a frequency or wavelength corresponding to the frequency or wavelength for the optical data communication mode to the sensor; and
wherein the sensor and the processor cooperate to detect and extract data from an incoming optical data signal.

23. The apparatus of claim 21 wherein the processor (1) determines a location in the field of view where a device is located that is capable of receiving the data messages and (2) identifies the determined location as a target for one or more ladar pulses in the optical communication mode that encode one or more data messages to be communicated to the device.

Assignees

• Aeye Inc

Inventors

• Dussan Luis Carlos
• Steinhardt Allan
• Cook David
• Lacorte Blair B

Classifications

• G01S7/4861 Primary

  Circuits for detection, sampling, integration or read-out · CPC title

• G01S7/006 Primary

  using shared front-end circuitry, e.g. antennas (G01S13/765, G01S13/825 take precedence) · CPC title

• G01S7/484

  Transmitters · CPC title

• G01S7/487

  Extracting wanted echo signals {, e.g. pulse detection} · CPC title

• G01S7/4816

  of receivers alone · CPC title