# US 2021/0278536 A1 · Method and system for time separated quadrature detection of doppler effects in optical range measurements > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0278536 A1 - Document ID: US20210278536A1 - Status: Published application - Kind: A1 - Application number: 17/331,362 - Filed: 2021-05-26 - Published: 2021-09-09 - Earliest claimed: 2017-07-10 - Assignees: Blackmore Sensors & Analytics, LLC - Applicants: Blackmore Sensors & Analytics, LLC - Inventors: Stephen C. CROUCH; Krishna Rupavatharam - Web page: https://patentgrep.com/patent/US20210278536A1 ## CPC - G01S 17/26: wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals - G01S 7/4866: {by fitting a model or function to the received signal} - G01S 7/4915: Time delay measurement, e.g. operational details for pixel components (signal extraction and conditioning G01S7/493); Phase measurement - G01S 17/34: using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal - G01S 17/89: for mapping or imaging - G01S 17/931: of land vehicles - G08G 1/04: using optical or ultrasonic detectors - G08G 1/16: Anti-collision systems (road vehicle drive control systems for predicting or avoiding probable or impending collision otherwise than by control of a particular sub-unit B60W30/08) - G08G 1/165: {for passive traffic, e.g. including static obstacles, trees} - G08G 1/166: {for active traffic, e.g. moving vehicles, pedestrians, bikes} - H04B 10/505: {using external modulation} - H04B 10/516: Details of coding or modulation - H04L 12/2801: {Broadband local area networks} - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - G08G: TRAFFIC CONTROL SYSTEMS (guiding railway traffic, ensuring the safety of railway traffic B61L; arrangement of road signs or traffic signals E01F9/00; radar or analogous systems, sonar systems, lidar systems specially adapted for traffic control G01S13/91, G01S15/88, G01S17/88; {radar or analogous systems, sonar systems, lidar systems specially adapted for anti-collision purposes G01S13/93, G01S15/93, G01S17/93}) - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract In some implementations, a light detection and ranging (LIDAR) system includes a transmitter configured to transmit an optical signal that is output from a laser and modulated based on a modulating signal, a receiver configured to receive a returned optical signal in response to transmitting the optical signal, and a processor. The processor is configured to produce a first optical signal based on the returned optical signal and a first version of the modulating signal, produce a second optical signal based on the returned optical signal and a second version of the modulating signal, generate a digital signal based on the first optical signal and the second optical signal, determine a Doppler frequency shift of the returned optical signal based, at least in part, on the digital signal, and provide data indicative of the Doppler frequency shift to a vehicle. ## Claims ### Claim 1 A light detection and ranging (LIDAR) system comprising: a transmitter configured to transmit an optical signal that is output from a laser and modulated based on a modulating signal; a receiver configured to receive a returned optical signal in response to transmitting the optical signal; a processor configured to: produce a first optical signal based on the returned optical signal and a first version of the modulating signal; produce a second optical signal based on the returned optical signal and a second version of the modulating signal; generate a digital signal based on the first optical signal and the second optical signal; determine a Doppler frequency shift of the returned optical signal based, at least in part, on the digital signal; and provide data indicative of the Doppler frequency shift to a vehicle. ### Claim 2 (depends on 1) The LIDAR system according to claim 1, wherein the processor is further configured to operate the vehicle based on the Doppler frequency shift. ### Claim 3 (depends on 1) The LIDAR system according to claim 1, further comprising a mixer configured to: mix, during a first time interval, the returned optical signal with a first reference optical signal that is modulated based on the first version of the modulating signal, to produce the first optical signal; and mix, during a second time interval, the returned optical signal with a second reference optical signal that is modulated based the second version of the modulating signal, to produce the second optical signal. ### Claim 4 (depends on 3) The LIDAR system according to claim 3, wherein the second time interval is non-overlapping with the first time interval. ### Claim 5 (depends on 4) The LIDAR system according to claim 4, wherein the first time interval and the second time interval occur an equal number of times randomly during a processing time interval. ### Claim 6 (depends on 3) The LIDAR system according to claim 3, wherein the first time interval and the second time interval alternate an equal number of times during a processing time interval. ### Claim 7 (depends on 1) The LIDAR system according to claim 1, wherein the modulating signal is a digital signal. ### Claim 8 (depends on 1) The LIDAR system according to claim 1, wherein the transmitted optical signal is a phase-encoded optical signal. ### Claim 9 (depends on 1) The LIDAR system according to claim 1, wherein the transmitted optical signal is an up and down chirped optical signal. ### Claim 10 (depends on 3) The LIDAR system according to claim 3, wherein the processor is configured to: detect the first optical signal during the first time interval to produce a first electrical signal; and detect the second optical signal during the second time interval to produce a second electrical signal. ### Claim 11 (depends on 10) The LIDAR system according to claim 10, wherein in generating the digital signal, the processor is configured to generate the digital signal by using a digitized sample of one of the first electrical signal and the second electrical signal as a real part of the digital signal and a digitized sample of a different one of the first electrical signal and the second electrical signal as an imaginary part of the digital signal. ### Claim 12 (depends on 1) The LIDAR system according to claim 1, wherein the processor is configured to determine the Doppler frequency shift of the returned optical signal based on a Fourier transform of the digital signal. ### Claim 13 (depends on 1) The LIDAR system according to claim 1, wherein the first version of the modulating signal is an in-phase version of the modulating signal, and the second version of the modulating signal is a quadrature version of the modulating signal representing a quadrature local oscillator signal. ### Claim 14 An autonomous vehicle control system comprising one or more processors, wherein the one or more processors are configured to: cause a transmitter to transmit an optical signal that is output from a laser and modulated based on a modulating signal; cause a receiver to receive a returned optical signal in response to transmitting the optical signal; produce a first optical signal based on the returned optical signal and a first version of the modulating signal; produce a second optical signal based on the returned optical signal and a second version of the modulating signal; generate a digital signal based on the first optical signal and the second optical signal; determine a Doppler frequency shift of the returned optical signal based, at least in part, on the digital signal; and operate a vehicle based on the Doppler frequency shift. ### Claim 15 (depends on 14) The autonomous vehicle control system according to claim 14, wherein the processor is further configured to cause a mixer to: mix, during a first time interval, the returned optical signal with a first reference optical signal that is modulated based on the first version of the modulating signal, to produce the first optical signal; and mix, during a second time interval, the returned optical signal with a second reference optical signal that is modulated based the second version of the modulating signal, to produce the second optical signal. ### Claim 16 (depends on 14) The autonomous vehicle control system according to claim 14, wherein the modulating signal is a digital signal. ### Claim 17 (depends on 14) The autonomous vehicle control system according to claim 14, wherein the transmitted optical signal is a phase-encoded optical signal. ### Claim 18 (depends on 14) The autonomous vehicle control system according to claim 14, wherein the transmitted optical signal is an up and down chirped optical signal. ### Claim 19 (depends on 14) The autonomous vehicle control system according to claim 14, wherein the first version of the modulating signal is an in-phase version of the modulating signal, and the second version of the modulating signal is a quadrature version of the modulating signal representing a quadrature local oscillator signal. ### Claim 20 A autonomous vehicle, comprising: a light detection and ranging (LIDAR) system including: a transmitter configured to transmit an optical signal that is output from a laser and modulated based on a modulating signal; a receiver configured to receive a returned optical signal in response to transmitting the optical signal; a processor configured to produce a first optical signal based on the returned optical signal and a first version of the modulating signal, produce a second optical signal based on the returned optical signal and a second version of the modulating signal, generate a digital signal based on the first optical signal and the second optical signal, and determine a Doppler frequency shift of the returned optical signal based, at least in part, on the digital signal; at least one of a steering system or a braking system; and a vehicle controller comprising one or more processors configured to control operation of the at least one of the steering system or the braking system based on the Doppler frequency shift.