Techniques for subband processing for a lidar system

Abstract

A frequency modulated continuous wave (FMCW) light detection and ranging (LIDAR) system includes a memory and a processor, operatively coupled to the memory, to generate a set of frequency subbands in a time domain based on an electrical signal from one or more optical detectors and filter the set of frequency subbands in the time domain based on one or more characteristics of each of the set of frequency subbands to obtain a subset of the set of frequency subbands based on at least two separate signal thresholds. The processor is further to convert the subset of the plurality of frequency subbands in the time domain to one or more subband signals in a frequency domain and detect signal peaks in the one or more subband signals in the frequency domain corresponding to target ranges in a field of view of the FMCW LIDAR system.

What is claimed is: 
     
         1 . A frequency modulated continuous wave (FMCW) LIDAR system, comprising:
 a memory; and   a processor, operatively coupled to the memory, to:
 generate a plurality of frequency subbands in a time domain based on an electrical signal from one or more optical detectors; 
 filter the plurality of frequency subbands in the time domain based on one or more characteristics of each of the plurality of frequency subbands to obtain a subset of the plurality of frequency subbands based on at least two separate signal thresholds; 
 convert the subset of the plurality of frequency subbands in the time domain to one or more subband signals in a frequency domain; and 
 detect signal peaks in the one or more subband signals in the frequency domain corresponding to target ranges in a field of view of the FMCW LIDAR system. 
   
     
     
         2 . The FMCW LIDAR system of  claim 1 , wherein the processor is further to:
 resample and combine the plurality of frequency subbands in the time domain into a combined time domain signal.   
     
     
         3 . The FMCW LIDAR system of  claim 1 , wherein to filter the plurality of frequency subbands, the processor is to:
 select the subset of frequency subbands in the time domain based on a set of subband selection criteria.   
     
     
         4 . The FMCW LIDAR system of  claim 1 , wherein the processor is further to:
 select a subset of the one or more subband signals in the frequency domain, wherein the signal peaks are detected from the subset of the one or more subband signals in the frequency domain.   
     
     
         5 . The FMCW LIDAR system of  claim 4 , wherein the subset of the one or more subband signals in the frequency domain is selected based on at least one of characteristics of the electrical signal, characteristics of the plurality of frequency subbands in the time domain, characteristics of the one or more subband signals in the frequency domain, and characteristics of a scene in a field of view of the LIDAR system. 
     
     
         6 . The FMCW LIDAR system of  claim 1 , wherein the one or more characteristics used to filter the plurality of frequency subbands in the time domain comprise at least one of:
 a total energy in a subband, a signal to noise ratio in the subband, a number of zero crossings, a number of clipped samples, energy variation over time, an azimuth angle of a scan associated with the subband, an elevation angle of the scan associated with the subband, a relative velocity of a detected target, scene characteristics, detection of objects in a previous LIDAR time segment, and a maximum number of allowed subbands.   
     
     
         7 . The FMCW LIDAR system of  claim 1 , wherein the signal peaks comprise at least one of a peak energy or a peak signal to noise ratio within the frequency domain. 
     
     
         8 . A method, comprising:
 generate, by a light detection and ranging (LIDAR) system, a plurality of frequency subbands in a time domain based on an electrical signal from one or more optical detectors;   filter, by a processing device of the LIDAR system, the plurality of frequency subbands in the time domain based on one or more characteristics of each of the plurality of frequency subbands to obtain a subset of the plurality of frequency subbands based on at least two separate signal thresholds;   convert, by the processing device, the subset of the plurality of frequency subbands in the time domain to one or more subband signals in a frequency domain; and   detect, by the processing device, signal peaks in the one or more subband signals in the frequency domain corresponding to target ranges in a field of view of the LIDAR system.   
     
     
         9 . The method of  claim 8 , further comprising:
 resampling and combining the plurality of frequency subbands in the time domain into a combined time domain signal.   
     
     
         10 . The method of  claim 8 , wherein filtering the plurality of frequency subbands, comprises:
 selecting the subset of frequency subbands in the time domain based on a set of subband selection criteria.   
     
     
         11 . The method of  claim 8 , further comprising:
 selecting a subset of the one or more subband signals in the frequency domain, wherein the signal peaks are detected from the subset of the one or more subband signals in the frequency domain.   
     
     
         12 . The method of  claim 11 , wherein the subset of the one or more subband signals in the frequency domain is selected based on at least one of characteristics of the electrical signal, characteristics of the plurality of frequency subbands in the time domain, characteristics of the one or more subband signals in the frequency domain, and characteristics of a scene in a field of view of the LIDAR system. 
     
     
         13 . The method of  claim 8 , wherein the one or more characteristics used to filter the plurality of frequency subbands in the time domain comprise at least one of:
 a total energy in a subband, a signal to noise ratio in the subband, a number of zero crossings, a number of clipped samples, energy variation over time, an azimuth angle of a scan associated with the subband, an elevation angle of the scan associated with the subband, a relative velocity of a detected target, scene characteristics, detection of objects in a previous LIDAR time segment, and a maximum number of allowed subbands.   
     
     
         14 . The method of  claim 8 , wherein the signal peaks comprise at least one of a peak energy or a peak signal to noise ratio within the frequency domain. 
     
     
         15 . A light detection and ranging (LIDAR) system, comprising:
 an optical source to transmit an optical beam toward a target;   an optical receiver to receive a return beam from the target comprising a reflection of the optical beam from the target, the optical receiver to produce an electrical signal in a time domain by combining the return beam with a local oscillator;   a circuitry; and   a memory to store instructions that, when executed by the circuitry, cause the system to:
 generate a plurality of frequency subbands in the time domain based on the electrical signal from the optical receiver; 
 filter the plurality of frequency subbands in the time domain based on one or more characteristics of each of the plurality of frequency subbands to obtain a subset of the plurality of frequency subbands based on at least two separate signal thresholds; 
 convert the subset of the plurality of frequency subbands in the time domain to one or more subband signals in a frequency domain; and 
 detect signal peaks in the one or more subband signals in the frequency domain corresponding to target ranges in a field of view of the LIDAR system. 
   
     
     
         16 . The LIDAR system of  claim 15 , wherein the circuitry is further to:
 resample and combine the plurality of frequency subbands in the time domain into a combined time domain signal.   
     
     
         17 . The LIDAR system of  claim 15 , wherein to filter the plurality of frequency subbands, the circuitry is to:
 select the subset of frequency subbands in the time domain based on a set of subband selection criteria.   
     
     
         18 . The LIDAR system of  claim 15 , wherein the circuitry is further to:
 select a subset of the one or more subband signals in the frequency domain, wherein the signal peaks are detected from the subset of the one or more subband signals in the frequency domain.   
     
     
         19 . The LIDAR system of  claim 18 , wherein the subset of the one or more subband signals in the frequency domain is selected based on at least one of characteristics of the electrical signal, characteristics of the plurality of frequency subbands in the time domain, characteristics of the one or more subband signals in the frequency domain, and characteristics of a scene in a field of view of the LIDAR system. 
     
     
         20 . The LIDAR system of  claim 15 , wherein the one or more characteristics used to filter the plurality of frequency subbands in the time domain comprise at least one of:
 a total energy in a subband, a signal to noise ratio in the subband, a number of zero crossings, a number of clipped samples, energy variation over time, an azimuth angle of a scan associated with the subband, an elevation angle of the scan associated with the subband, a relative velocity of a detected target, scene characteristics, detection of objects in a previous LIDAR time segment, and a maximum number of allowed subbands.