Direct detection LiDAR system and method with pulse amplitude modulation (AM) transmitter and quadrature receiver

• US 10,838,062 B2
• Filed: 08/02/2016
• Issued: 11/17/2020
• Est. Priority Date: 05/24/2016
• Status: Active Grant

• Current Assignee: Veoneer, Inc. (SSW Partners LP)
• Original Assignee: Veoneer US Inc. (SSW Partners LP)
• Inventors: de Mersseman, Bernard, Puglia, Kenneth V.
• Primary Examiner(s): Hulka, James R
• Application Number:
  US15/226,435
• Publication Number:
  US 20170343671A1
• Time in Patent Office: 1,568 Days
• Field of Search: 356 501
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/26 wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals
• CPC Class Codes: G01S 17/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/486 Receivers

Abstract

A LiDAR system and method includes a pulse modulation circuit and an amplitude modulation circuit for applying pulse modulation and amplitude modulation to a continuous signal to generate a plurality of amplitude-modulated pulses of the continuous signal. An optical modulation circuit applies the amplitude-modulated pulses of the continuous signal to an optical signal to generate a pulse amplitude-modulated (PAM) optical signal. Optical transmission elements transmit the PAM optical signal into a region, and optical receiving elements receive reflected optical signals from the region. Receive signal processing circuitry uses quadrature detection to process the reflected optical signals.

Claims

1. A direct detection LiDAR system, comprising:

a signal generator for generating a continuous periodic signal;

a pulse modulation circuit for applying a pulse modulation signal to the continuous periodic signal to convert the continuous periodic signal into a plurality of pulses of the continuous periodic signal;

an amplitude modulation circuit for generating a sinusoidal amplitude modulation envelope signal and applying the sinusoidal amplitude modulation envelope signal to the plurality of pulses to generate a plurality of amplitude-modulated pulses of the continuous periodic signal;

an optical modulation circuit for receiving the plurality of amplitude-modulated pulses of the continuous periodic signal and applying the amplitude-modulated pulses of the continuous periodic signal to an optical signal to generate a pulse amplitude-modulated (PAM) optical signal;

optical transmission elements for transmitting the PAM optical signal into a region;

optical receiving elements for receiving reflected optical signals from the region; and

receive signal processing circuitry for receiving the reflected optical signals and using quadrature detection to process the reflected optical signals, the receive signal processing circuitry comprising light detection elements which demodulate the reflected optical signals to recover a portion of a reflected version of the continuous periodic signal from a reflected version of the pulse amplitude modulated optical signal.

2. The direct detection LiDAR system of claim 1, wherein the receive signal processing circuitry includes a pair of I/Q mixers, each of the pair of I/Q mixers comprising a first input, the first inputs of the pair of I/Q mixers being coupled to the light detection elements to receive the portion of the reflected version of the continuous periodic signal, each of the I/Q mixers comprising an output, the outputs of the I/Q mixers being coupled to respective analog-to-digital converter circuits to provide a pulse modulation envelope signal to the respective analog-to-digital converter circuits.

3. The direct detection LiDAR system of claim 2, wherein the receive signal processing circuitry includes phase shifting circuitry for splitting the continuous periodic signal from the signal generator into a pair of split signals and applying a phase shift to one of the pair of split signals to generate a first local oscillator (LO) signal and a second phase-shifted LO signal, the first LO signal and the second phase shifted LO signal being applied to respective second inputs of respective ones of the pair of I/Q mixers.

4. The direct detection LiDAR system of claim 3, wherein the phase shift is 90 degrees, such that the first LO signal and the second phase-shifted LO signal are in quadrature.

5. The direct detection LiDAR system of claim 1, wherein the continuous periodic signal is a sinusoidal signal.

6. The direct detection LiDAR system of claim 1, wherein the continuous periodic signal is a square wave signal.

7. The direct detection LiDAR system of claim 1, wherein the LiDAR system is installed and operates in an automobile.

8. A direct detection LiDAR method, comprising:

generating a continuous periodic signal;

applying a pulse modulation signal to the continuous periodic signal to convert the continuous periodic signal into a plurality of pulses of the continuous periodic signal;

generating a sinusoidal amplitude modulation envelope signal and applying the sinusoidal amplitude modulation envelope signal to the plurality of pulses to generate a plurality of amplitude-modulated pulses of the continuous periodic signal;

applying the plurality of amplitude-modulated pulses of the continuous periodic signal to an optical signal to generate a pulse amplitude-modulated (PAM) optical signal;

transmitting the PAM optical signal into a region;

receiving reflected optical signals from the region; and

processing the reflected optical signals using quadrature detection, the processing comprising demodulating the reflected optical signals to recover a portion of a reflected version of the continuous periodic signal from a reflected version of the pulse amplitude modulated optical signal.

9. The direct detection LiDAR method of claim 8, wherein each of a pair of I/Q mixers comprises a first input for receiving the portion of the reflected version of the continuous periodic signal, each of the I/Q mixers comprising an output, the outputs of the I/Q mixers being couple to respective analog-to-digital converter circuits to provide pulse modulation envelope signal to the respective analog-to-digital converter circuits.

10. The direct detection LiDAR method of claim 9, further comprising splitting the continuous periodic signal from the signal generator into a pair of split signals and applying a phase shift to one of the pair of split signals to generate a first local oscillator (LO) signal and a second phase-shifted LO signal, the first LO signal and the second phase shifted LO signal being applied to respective second inputs of respective ones of the pair of I/Q mixers.

11. The direct detection LiDAR method of claim 10, wherein the phase shift is 90 degrees, such that the first LO signal and the second phase-shifted LO signal are in quadrature.

12. The direct detection LiDAR method of claim 8, wherein the continuous periodic signal is a sinusoidal signal.

13. The direct detection LiDAR method of claim 8, wherein the continuous periodic signal is a square wave signal.

14. The direct detection LiDAR method of claim 8, wherein the method is performed in an automobile.