Reduction of ADC sampling rates in LIDAR systems

Patent metadata

Field	Value
Publication number	US-12535586-B2
Application number	US-201916395128-A
Country	US
Kind code	B2
Filing date	Apr 25, 2019
Priority date	Aug 31, 2018
Publication date	Jan 27, 2026
Grant date	Jan 27, 2026

Abstract

A LIDAR system includes a LIDAR chip that is configured to output a LIDAR output signal such that the LIDAR output signal can be reflected by an object located off the LIDAR chip. The LIDAR chip is also configured to receive a LIDAR input signal that includes light from the reflected LIDAR output signal. The LIDAR chip is configured to combine the LIDAR input signal with a reference signal so as to produce a beating signal. The electronics operate the LIDAR chip such that the effects of radial velocity between the reflecting object are reduced or removed from the beating signal while measuring the distance between the LIDAR chip and the reflecting object. The electronics operate the LIDAR chip such that the effects of the distance between the reflecting object are reduced or removed from the beating signal while measuring the radial velocity between the LIDAR chip and the reflecting object.

First claim

The invention claimed is:

1 . A LIDAR system, comprising:
a LIDAR chip having a waveguide configured to guide an outgoing LIDAR signal,
the LIDAR chip also configured to output a LIDAR output signal that includes light from the outgoing LIDAR signal,
the LIDAR chip also being configured to receive a LIDAR input signal,
the LIDAR chip including a signal combiner configured to combine a comparative signal with a reference signal so as to produce a composite signal beating at a beat frequency that is a difference between a frequency of the comparative signal and a frequency of the reference signal,
the comparative signal including light from the LIDAR input signal, and
the reference signal including light from the outgoing LIDAR signal and excluding light from the LIDAR input signal; and
electronics that calculate a distance between the LIDAR chip and an object that is moving with a radial velocity relative to the LIDAR system and that reflects the LIDAR output signal such that the LIDAR input signal includes light from the LIDAR output signal, the electronics calculating the distance as c*Δf/(2α) where c represents a speed of light, Δf represents the beat frequency, and α represents a rate of change in a frequency of the LIDAR output signal during the data period.

2 . The system of claim 1 , wherein the electronics operate the LIDAR system in a series of cycles that each has a distance period and a velocity period, the LIDAR output signal during each of the distance periods has a carrier signal with an amplitude modulated by an amplitude modulation signal that is a function of a sinusoid with a chirped frequency.

3 . The system of claim 2 , wherein during the distance periods a contribution of the radial velocity to the beat frequency is less than 10% of what the contribution to the beat frequency would be with LIDAR output signal replaced by a continuous wave with the same frequency as the LIDAR output signal.

4 . The system of claim 3 , wherein the LIDAR output signal during the distance periods has a carrier signal with an amplitude modulated by an amplitude modulation signal that is a function of a sinusoid with a chirped frequency.

5 . The system of claim 3 , wherein the LIDAR output signal generated during the distance periods can be represented by [M+N*cos(E+C*t+D*t 2 )] 1/2 cos(F*t) where M, N, C, D, E and F are constants, t represents time, M>0, N>0, M≥N, C≠0, D≠0, and F≠0.

6 . The system of claim 3 , wherein the beat frequency is not a function of the radial velocity between the LIDAR chip and the reflecting object.

7 . The system of claim 3 , wherein during the velocity periods the electronics generate the LIDAR output signal as a continuous wave and use the LIDAR input signal that results from the continuous wave LIDAR input signal to determine the radial velocity between the LIDAR chip and the reflecting object.

8 . The system of claim 2 , wherein the composite signal during the distance periods is an in-phase component of a complex signal.

9 . The system of claim 8 , wherein the electronics perform a real transform Fourier transform on the complex signal so as to identify the beat frequency of the composite signal.

10 . The system of claim 8 , wherein a complex transform is performed on the complex signal.

11 . The system of claim 2 , wherein the LIDAR output signal is a continuous wave during the velocity periods.

12 . The system of claim 1 , wherein the electronics receive an electrical signal beating at the beat frequency from a balanced detector.

13 . The system of claim 1 , wherein the electronics include a transform component that performs a mathematical transform on the electrical signal and outputs the beat frequency.

14 . The system of claim 1 , wherein the LIDAR output signal is represented by [M+N*cos(E+C*t+D*t 2 )] 1/2 cos(F*t) where M, N, C, D, E and F are constants, t represents time, M>0, N>0, M≥N, C≠0, D≠0, and F≠0.

15 . The system of claim 14 , wherein F>C.

16 . The system of claim 15 , wherein F represents 2πf c and C represents 2πf 1 and a ratio of f c : f 1 is greater than 2:1.

17 . The system of claim 16 , wherein the ratio of f c :f 1 is greater than 5×10 4 : 1.

18 . The system of claim 15 , wherein the LIDAR output signal is represented by [M+N*cos(E+C*t+D*t 2 )] 1/2 cos(F*t) where M, N, C, D, E and F are constants, t represents time, M>0, N>0, and M≥N, C≠0, D≠0, and F≠0.

19 . The system of claim 18 , wherein F represents 2 πf c and C represents 2 πf 1 and a ratio of f c :f 1 is greater than 5×10 4 :1.

20 . A system, comprising:
a LIDAR system that includes a LIDAR chip having a waveguide configured to guide an outgoing LIDAR signal,
the LIDAR chip also configured to output a LIDAR output signal that includes light from the outgoing LIDAR signal,
the LIDAR chip also being configured to receive a LIDAR input signal,
the LIDAR chip including a signal combiner configured to combine a comparative signal with a reference signal so as to produce a composite signal beating at a beat frequency that is a difference between a frequency of the comparative signal and a frequency of the reference signal,
the comparative signal including light from the LIDAR input signal, and
the reference signal including light from the outgoing LIDAR signal and excluding light from the LIDAR input signal;
an object moving with a radial velocity relative to the LIDAR system and reflecting the LIDAR output signal such that the LIDAR input signal includes light from the reflected LIDAR output signal that was reflected by the object; and the LIDAR system including electronics that calculate a distance between the LIDAR chip and the object as c*Δf/(2α) where c represents a speed of light, Δf represents the beat frequency, and a represents a rate of change in a frequency of the LIDAR output signal during the data period.

Assignees

• Silc Tech Inc

Inventors

• Boloorian Majid
• Feng Dazeng
• Asghari Mehdi

Classifications

• G01S17/32

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

• G01S7/4915

  Time delay measurement, e.g. operational details for pixel components (signal extraction and conditioning G01S7/493); Phase measurement · CPC title

• G01S7/4913

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

• G01S7/4911

  Transmitters · CPC title

• G01S17/58 Primary

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