Lidar system and method of operation

Abstract

A method of lidar system operation, preferably including: determining a signal, outputting the signal, receiving a return signal, and/or analyzing the return signal. A lidar system, preferably including one or more: optical emitters, optical detectors, beam directors, and/or processing modules. A class of spectrally decimated encodings, wherein multiple codes of this class, all preferably mutually spectrally-orthogonal, can be generated based on a single input encoding.

We claim: 
     
         1 . A method for environment mapping, comprising:
 selecting an input encoding;   generating, via spectral decimation of the input encoding, a set of spectrally-orthogonal encodings comprising a first encoding and a second encoding, wherein generating the set comprises, based on a frequency-domain representation of the input encoding, the frequency-domain representation of the input encoding defining a first number n of frequency bins of non-zero amplitude:
 generating a frequency-domain representation of the first encoding, the frequency-domain representation of the first encoding defining a second number of frequency bins, wherein the second number is equal to or greater than 2n−1; and 
 generating a frequency-domain representation of the second encoding, the frequency-domain representation of the second encoding defining a third number of frequency bins, wherein the third number is equal to or greater than 2n−1; 
   generating a first optical output representative of a first output signal, comprising modulating a first carrier signal based on the first encoding;   generating a second optical output representative of a second output signal, comprising modulating a second carrier signal based on the second encoding;   during a time period:
 transmitting the first optical output into an environment; and 
 transmitting the second optical output into the environment; 
   at an optical sensor, receiving a return signal, the return signal comprising:
 a first reflection, from a first object within the environment, of the first optical output; and 
 a second reflection, from a second object within the environment, of the second optical output; 
   determining a sample by selecting a contiguous time window of the return signal;   generating a first filtered sample, comprising filtering the sample based on the first encoding;   determining a first phase delay associated with the first filtered sample; and   based on the first phase delay, determining a relative location of the first object.   
     
     
         2 . The method of  claim 1 , further comprising:
 generating a second filtered sample, comprising filtering the sample based on the second encoding;   determining a second delay time associated with the second filtered sample; and   based on the second delay time, determining a relative location of the second object.   
     
     
         3 . The method of  claim 2 , wherein the first output signal is periodic and the second output signal is periodic. 
     
     
         4 . The method of  claim 3 , wherein:
 the first output signal comprises:
 a first encoding portion representative of the first encoding; and 
 a first temporal gap; and 
   the second output signal comprises:
 a second encoding portion representative of the second encoding; and 
 a second temporal gap. 
   
     
     
         5 . The method of  claim 4 , wherein a first duration of the first output signal is substantially equal to a second duration of the second output signal. 
     
     
         6 . The method of  claim 2 , wherein transmitting the first and second optical outputs is performed substantially concurrently. 
     
     
         7 . The method of  claim 1 , further comprising:
 determining a second sample by selecting a second contiguous time window of the return signal;   generating a second filtered sample, comprising filtering the second sample based on the second encoding;   determining a second delay time associated with the second filtered sample; and   based on the second delay time, determining a relative location of the second object.   
     
     
         8 . The method of  claim 7 , wherein the first output signal is periodic and the second output signal is periodic. 
     
     
         9 . The method of  claim 8 , wherein:
 the first output signal comprises:
 a first encoding portion representative of the first encoding; and 
 a first temporal gap; and 
   the second output signal comprises:
 a second encoding portion representative of the second encoding; and 
 a second temporal gap. 
   
     
     
         10 . The method of  claim 1 , wherein:
 the number of frequency bins of non-zero amplitude in the frequency-domain representation of the first encoding is n; and   the number of frequency bins of non-zero amplitude of non-zero amplitude in the frequency-domain representation of the second encoding is n.   
     
     
         11 . The method of  claim 10 , wherein:
 generating the frequency-domain representation of the first encoding is performed based on a first bijective mapping from the frequency bins of non-zero amplitude of the frequency-domain representation of the input encoding to the frequency bins of non-zero amplitude of the frequency-domain representation of the first encoding, wherein the amplitudes of each pair of frequency bins of non-zero amplitude defined by the first bijective mapping are equal; and   generating the frequency-domain representation of the second encoding is performed based on a second bijective mapping from the frequency bins of non-zero amplitude of the frequency-domain representation of the input encoding to the frequency bins of non-zero amplitude of the frequency-domain representation of the second encoding, wherein the amplitudes of each pair of frequency bins of non-zero amplitude defined by the second bijective mapping are equal, wherein the second bijective mapping differs from the first bijective mapping.   
     
     
         12 . The method of  claim 1 , wherein the second number is equal to the third number. 
     
     
         13 . The method of  claim 12 , wherein:
 generating the set of spectrally-orthogonal encodings is performed via d-fold spectral decimation of the input encoding; and   the second number is equal to or greater than nd−d+1.   
     
     
         14 . The method of  claim 13 , wherein the set of spectrally-orthogonal encodings has a cardinality equal to d. 
     
     
         15 . The method of  claim 1 , further comprising:
 selecting a second input encoding;   generating, via spectral decimation of the second input encoding, a second set of spectrally-orthogonal encodings comprising a third encoding and a fourth encoding;   generating a third optical output representative of a third output signal, comprising modulating a third carrier signal based on the third encoding;   generating a fourth optical output representative of a fourth output signal, comprising modulating a fourth carrier signal based on the fourth encoding;   during the time period, transmitting the third and fourth optical outputs into the environment; wherein the return signal further comprises:
 a third reflection, from a third object within the environment, of the third optical output; and 
 a fourth reflection, from a fourth object within the environment, of the fourth optical output; 
   generating a third filtered sample, comprising filtering a portion of the return signal based on the third encoding;   determining a third phase delay associated with the third filtered sample; and   based on the third phase delay, determining a relative location of the third object.   
     
     
         16 . The method of  claim 15 , wherein the portion of the return signal is the sample. 
     
     
         17 . The method of  claim 15 , wherein transmitting the first and third optical outputs is performed substantially concurrently. 
     
     
         18 . The method of  claim 15 , wherein transmitting the third and fourth optical outputs is performed substantially concurrently, the method further comprising:
 generating a fourth filtered sample, comprising filtering the based on the fourth encoding;   determining a fourth phase delay associated with the fourth filtered sample; and   based on the fourth phase delay, determining a relative location of the fourth object.   
     
     
         19 . The method of  claim 18 , wherein transmitting the first, second, third, and fourth optical outputs is performed substantially concurrently. 
     
     
         20 . The method of  claim 15 , wherein the first, second, third, and fourth output signals are periodic.