Method and system for sidelobe suppression in phase encoded doppler lidar

Abstract

A method for controlling a light detection and ranging (LIDAR) sensor system includes determining a code that has a first set of symbols having a first number of symbols. An optical signal generated based on the code is transmitted to an environment. The first set of symbols are transmitted as part of the optical signal in a first duration. In response to transmitting the optical signal, a returned optical signal that is reflected from an object in the environment is received. A second number of symbols to be sampled is determined, the second number of symbols being different than the first number of symbols. A second set of symbols having the second number of symbols is sampled in a second duration based on the returned optical signal. A range to the object is determined based on the second set of symbols.

What is claimed: 
     
         1 . A method for controlling a light detection and ranging (LIDAR) sensor system including one or more processors, the method comprising:
 determining, by the one or more processors, a code that has a first set of symbols having a first number of symbols;   transmitting, by the one or more processors to an environment, an optical signal generated based on the code, wherein the first set of symbols are transmitted as part of the optical signal in a first duration;   in response to transmitting the optical signal, receiving, by the one or more processors, a returned optical signal that is reflected from an object in the environment;   determining, by the one or more processors, a second number of symbols to be sampled, the second number of symbols being different than the first number of symbols;   sampling, by the one or more processors based on the returned optical signal, a second set of symbols in a second duration, wherein the second set of symbols have the second number of symbols; and   determining, by the one or more processors based on the second set of symbols, a range to the object.   
     
     
         2 . The method as recited in  claim 1 , wherein a length of the second duration is the same as or substantially similar to a length of the first duration. 
     
     
         3 . The method as recited in  claim 1 , wherein
 the second set of symbols are sampled based on a first clock signal, and   the method further comprising:
 adjusting the first clock signal to generate a second clock signal based on which another set of symbols are to be transmitted, wherein the another set of symbols have the first number of symbols. 
   
     
     
         4 . The method as recited in  claim 1 , wherein transmitting the first set of symbols comprises:
 padding the code by adding one or more symbols to the code such that the code has the second number of symbols.   
     
     
         5 . The method as recited in  claim 4 , further comprising:
 inserting the one or more symbols to the code at an insertion location such that a symbol of the inserted symbols matches at least one of symbols that are adjacent to the insertion location.   
     
     
         6 . The method as recited in  claim 1 , wherein transmitting the first set of symbols comprises:
 performing an interpolation on the first set of symbols to generate a third set of symbols in the code, such that the code has the second number of symbols.   
     
     
         7 . The method as recited in  claim 1 , wherein transmitting the first set of symbols comprises:
 up-sampling the code to generate a sample signal; and   filtering the sample signal to generate a smoothed signal.   
     
     
         8 . The method as recited in  claim 1 , wherein the smoothed signal is generated using a low-pass digital filter. 
     
     
         9 . The method as recited in  claim 1 , wherein sampling the second set of symbols comprises:
 sampling, from the returned optical signal, a fourth set of symbols; and   performing an interpolation on the fourth set of symbols to generate the second set of symbols.   
     
     
         10 . The method as recited in  claim 1 , further comprising:
 generating, based on the returned optical signal, an electrical signal; and   determining the range to the object based on a Fourier Transform of the electrical signal.   
     
     
         11 . The method as recited in  claim 1 , further comprising:
 providing operation signals to a vehicle control system of a vehicle such that the vehicle control system controls the vehicle using the range to the object.   
     
     
         12 . A method for controlling a vehicle using a light detection and ranging (LIDAR) sensor system and one or more processors, comprising:
 determining, by the LIDAR sensor system, a code that has a first set of symbols having a first number of symbols;   transmitting, by the LIDAR sensor system to an environment, an optical signal generated based on the code, wherein the first set of symbols are transmitted as part of the optical signal in a first duration;   in response to transmitting the optical signal, receiving, by the LIDAR sensor system, a returned optical signal that is reflected from an object in the environment;   determining, by the LIDAR sensor system, a second number of symbols to be sampled, the second number of symbols being different than the first number of symbols;   sampling, by the LIDAR sensor system based on the returned optical signal, a second set of symbols in a second duration, wherein the second set of symbols have the second number of symbols; and   determining, by the LIDAR sensor system based on the second set of symbols, a range to the object; and   controlling, by the one or more processors, operation of the vehicle using the range to the object.   
     
     
         13 . The method as recited in  claim 12 , wherein a length of the second duration is the same as or substantially similar to a length of the first duration. 
     
     
         14 . The method as recited in  claim 12 , wherein
 the second set of symbols are sampled based on a first clock signal, and   the method further comprising:
 adjusting the first clock signal to generate a second clock signal based on which another set of symbols are to be transmitted, wherein the another set of symbols have the first number of symbols. 
   
     
     
         15 . The method as recited in  claim 12 , wherein transmitting the first set of symbols comprises:
 padding the code by adding one or more symbols to the code such that the code has the second number of symbols.   
     
     
         16 . The method as recited in  claim 15 , further comprising:
 inserting the one or more symbols to the code at an insertion location such that a symbol of the inserted symbols matches at least one of symbols that are adjacent to the insertion location.   
     
     
         17 . The method as recited in  claim 12 , wherein transmitting the first set of symbols comprises:
 performing an interpolation on the first set of symbols to generate a third set of symbols in the code, such that the code has the second number of symbols.   
     
     
         18 . The method as recited in  claim 12 , wherein transmitting the first set of symbols comprises:
 up-sampling the code to generate a sample signal; and   filtering the sample signal using a low-pass digital filter to generate a smoothed signal.   
     
     
         19 . The method as recited in  claim 12 , wherein sampling the second set of symbols comprises:
 sampling, from the returned optical signal, a fourth set of symbols; and   performing an interpolation on the fourth set of symbols to generate the second set of symbols.   
     
     
         20 . The method as recited in  claim 12 , further comprising:
 generating, based on the returned optical signal, an electrical signal; and   determining the range to the object based on a Fourier Transform of the electrical signal.