Phase noise compensation for frequency-modulated continuous wave (FMCW) light detection and ranging (LIDAR) systems

Abstract

Phase noise compensation for frequency-modulated continuous-wave optical detection and ranging (LIDAR) systems. [Solution] The system includes a detector that receives an optical signal from the light source of a LIDAR system, separates the optical signal into a first optical signal and a second optical signal into a first path and a second path having a preset delay, and detects the optical signal combined with an optical interferometer that combines the optical signals that have passed through the first path and the second path; a phase noise determination module that receives the detected signal and determines a plurality of phase noise signals corresponding to an integer multiple of a preset delay; and a phase noise compensation module that receives a LIDAR response signal, compensates for the phase noise in the LIDAR response signal for each branch using one of the phase noise signals, determines a Fast Fourier Transform (FFT) for a specific distance range to the target for the compensated signal, and is configured so that each branch determines an FFT for a different range.

Claims

1. A device for phase noise compensation in a frequency-modulated continuous wave (FMCW) optical detection and ranging (LIDAR) system, wherein the device is An optical interferometer configured to receive an optical signal, wherein the optical signal is an FMCW optical signal generated by the light source of the FMCW Lidar system, and the optical interferometer is configured to separate the optical signal into a first optical signal propagating in a first path and a second optical signal propagating in a second path, wherein the first path has a preset delay relative to the second path, and combines the first optical signal and the second optical signal that have passed through the first path and the second path, respectively. A detector for detecting the combined first optical signal and the second optical signal, A phase noise determination module configured to receive a detected signal from the detector and determine a plurality of phase noise signals corresponding to an integer multiple of the predetermined delay, A phase noise compensation module is configured to receive a LIDAR response signal and process the LIDAR response signal in a plurality of branches, wherein for each branch, the phase noise compensation module is configured to compensate for the phase noise in the LIDAR response signal using one of the plurality of phase noise signals, and to determine a Fast Fourier Transform (FFT) for the compensated LIDAR response signal for a specific distance range to a target, and the branches are configured to determine FFTs for different ranges from each other. A device equipped with the following features.

2. The apparatus according to claim 1, wherein the phase noise compensation module is further configured to combine the FFTs of the compensated LiDAR response signals from all of the branches to thereby compile the FFT of the compensated LiDAR response signals for the entire distance range to the target.

3. For each branch, the phase noise compensation module is configured to determine one of a plurality of phase noise signals used to compensate for the phase noise in the LIDAR response signal, wherein the determination comprises selecting a candidate phase noise signal from the plurality of phase noise signals and testing the candidate phase noise signal, according to claim 1.

4. The apparatus according to claim 3, wherein the determination comprises iteratively selecting a candidate phase noise signal from a plurality of phase noise signals and testing the candidate phase noise signal.

5. For each branch, the phase noise compensation module is configured to determine one of a plurality of phase noise signals used to compensate for the phase noise in the LIDAR response signal, where the determination is as follows: Selecting a set of candidate phase noise signals from multiple phase noise signals, wherein the candidate phase noise signals in the set are distributed such that they correspond to non-consecutive integer values. For each of the candidate phase noise signals, Compensating the LIDAR response signal using the candidate phase noise signal, and To determine the FFT of the compensated LIDAR response signal, By doing so, the candidate phase noise signal is tested. Identifying the candidate phase noise signal with the highest maximum peak power after FFT, Selecting the identified candidate phase noise signal, selecting a new set of candidate phase noise signals around the identified candidate phase noise signal, testing the candidate phase noise signals of the new set, and updating the identification of the candidate phase noise signal with the highest maximum peak power after the FFT, are repeated iteratively. At the end of the iterative process, one of several phase noise signals used to compensate for the phase noise in the LIDAR response signal is determined based on the candidate phase noise signal with the highest maximum peak power after the FFT. The apparatus according to claim 1, comprising:

6. The apparatus according to claim 5, wherein the new set of candidate phase noise signals includes two new candidate phase noise signals selected symmetrically around the identified candidate phase noise signal, the distance to the identified candidate phase noise signal is less than the distance between the identified candidate phase noise signal and adjacent candidate phase noise signals in the preceding set of candidate phase noise signals, and the distance from any one of the two new candidate phase noise signals to the identified candidate phase noise signal is iteratively smaller.

7. The phase noise determination module is Extracting the phase angle ramp of the detected signal, The condition that the phase difference between a certain phase angle of the phase angle lamp and the consecutive phase angles of the phase angle lamp is greater than or equal to 2π, then a multiple of 2π is added to the consecutive phase angles of the phase angle lamp, Subtracting a reference phase angle ramp from the extracted phase angle ramp, wherein the slope of the reference phase angle ramp is determined by the preset delay in order to determine the phase noise signal among a plurality of phase noise signals, corresponding to the preset delay. The apparatus according to claim 1, further configured to perform the following:

8. The apparatus according to claim 1, wherein the preset delay of the first path with respect to the second path is one of a fixed preset delay or an adjustable preset delay.

9. The apparatus according to claim 1, wherein the phase noise determination module is further configured to determine the plurality of phase noise signals, further including phase noise signals corresponding to non-integer multiples of the preset delay.

10. The apparatus according to claim 1, wherein the detector is a balanced photodiode.

11. A frequency-modulated continuous wave (FMCW) optical detection and ranging (LIDAR) system, The apparatus for phase noise compensation according to claim 1, A light source configured to generate an optical signal, wherein the light source is A laser configured to generate an optical carrier signal, A frequency modulation module configured to modulate the frequency of the optical carrier signal, An optical beam splitter is positioned in the path of the modulated optical carrier signal and configured to separate the modulated optical carrier signal into a lidar radiation signal emitted from the FMCW lidar system and the optical signal sent to the optical interferometer of the device for phase noise compensation. Equipped with, A LiDAR detector configured to detect light from the LiDAR emission signal reflected back toward the FMCW LiDAR system in order to detect the LiDAR response signal. A frequency-modulated continuous wave (FMCW) optical detection and ranging (LIDAR) system comprising the following features.

12. A method for phase noise compensation in a frequency-modulated continuous wave (FMCW) optical detection and ranging (LIDAR) system, wherein the method is: The optical interferometer receives an optical signal, and the optical signal is an FMCW optical signal generated by the light source of the FMCW LIDAR system. The optical interferometer separates the optical signal into a first optical signal propagating along a first path and a second optical signal propagating along a second path, wherein the first path has a predetermined delay relative to the second path. The optical interferometer combines the first optical signal and the second optical signal that have passed through the first path and the second path, respectively. The detector detects the combined first optical signal and the second optical signal, The phase noise determination module receives the detected signal from the detector, The phase noise determination module determines a plurality of phase noise signals corresponding to an integer multiple of the predetermined delay, The phase noise compensation module receives the LIDAR response signal, The phase noise compensation module processes the LIDAR response signal at multiple branches, and here, for each branch, Compensating for the phase noise in the LIDAR response signal using one of the multiple phase noise signals, The Fast Fourier Transform (FFT) is determined for a specific distance range to the target for the compensated LiDAR response signal, and the branch is configured to determine the FFT for different ranges. A method that includes [a certain feature].

13. The phase noise compensation module combines the FFTs of the compensated LiDAR response signals from all the branches, thereby compiling the FFT of the compensated LiDAR response signals for the entire distance range to the target. The method according to claim 12, further comprising:

14. For each branch, The method according to claim 12, further comprising determining one of a plurality of phase noise signals used to compensate for the phase noise in the LIDAR response signal, wherein the determination comprises selecting a candidate phase noise signal from the plurality of phase noise signals and testing the candidate phase noise signal.

15. For each branch, the phase noise compensation module further determines one of a plurality of phase noise signals used to compensate for the phase noise in the LIDAR response signal, wherein the determination is Selecting a set of candidate phase noise signals from multiple phase noise signals, wherein the candidate phase noise signals in the set are distributed such that they correspond to non-consecutive integer values. For each of the candidate phase noise signals, Compensating the LIDAR response signal using the candidate phase noise signal, and To determine the FFT of the compensated LIDAR response signal, This involves testing the candidate phase noise signal, Identifying the candidate phase noise signal with the highest maximum peak power after FFT, Selecting the identified candidate phase noise signal, selecting a new set of candidate phase noise signals around the identified candidate phase noise signal, testing the candidate phase noise signals of the new set, and updating the identification of the candidate phase noise signal with the highest maximum peak power after the FFT, are repeated iteratively. At the end of the aforementioned iterative process, one of a plurality of phase noise signals used to compensate for the phase noise in the LIDAR response signal is determined based on the candidate phase noise signal with the highest maximum peak power after the FFT. The method according to claim 12, comprising:

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