US 12,436,245 B2
Linearization of chirp in coherent lidar systems
Sunil Khatana, Sunnyvale, CA (US); and Tyler Banas, Alameda, CA (US)
Assigned to VELODYNE LIDAR USA, INC., San Jose, CA (US)
Filed by VELODYNE LIDAR USA, INC., San Jose, CA (US)
Filed on May 12, 2021, as Appl. No. 17/318,441.
Prior Publication US 2022/0365184 A1, Nov. 17, 2022
Int. Cl. G01S 7/497 (2006.01); G01S 7/4911 (2020.01); G01S 17/34 (2020.01); G01S 17/58 (2006.01)
CPC G01S 7/497 (2013.01) [G01S 7/4911 (2013.01); G01S 17/34 (2020.01); G01S 17/58 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A method for linearizing frequency chirp in a frequency-modulated continuous wave (FMCW) coherent LiDAR system, the method comprising:
generating a continuous wave laser signal having a frequency characteristic, the frequency characteristic comprising a frequency chirp over a frequency band in at least one period;
receiving a signal based on the generated laser signal;
mixing the received signal with a local oscillator signal, the local oscillator signal having the frequency characteristic;
determining at least one beat frequency based on the mixed signal;
sampling the mixed signal at a rate equal to at least two times the beat frequency;
determining a correction signal based on the sampled signal; and
providing the correction signal to a modulator coupled to a laser, the laser configured to generate the continuous wave laser signal, wherein an ideal signal has an ideal frequency characteristic, the ideal frequency characteristic comprising a linear frequency chirp over the frequency band in the at least one period, and for a given sample in the sampled signal, the correction signal indicates a difference between the frequency characteristic of the laser signal and the ideal frequency characteristic.