System and method for sensing distance and/or movement

Abstract

A method (e.g., a method for measuring a separation distance to a target object) includes transmitting an electromagnetic first transmitted signal from a transmitting antenna toward a target object that is a separated from the transmitting antenna by a separation distance. The first transmitted signal includes a first transmit pattern representative of a first sequence of digital bits. The method also includes receiving a first echo of the first transmitted signal that is reflected off the target object, converting the first echo into a first digitized echo signal, and comparing a first receive pattern representative of a second sequence of digital bits to the first digitized echo signal to determine a time of flight of the first transmitted signal and the echo.

What is claimed is: 
     
         1 . A method comprising:
 obtaining a two-dimensional image of an imaged object;   determining a calculated size of the imaged object from the two-dimensional image;   transmitting an electromagnetic signal toward the imaged object, the electromagnetic signal representative of a first digital sequence;   receiving an echo of the electromagnetic signal;   determining a separation distance to the imaged object by digitally comparing a digital echo signal that is representative of the echo with the first digital sequence that is represented by the electromagnetic signal; and   correcting the calculated size of the imaged object that was determined using the separation distance.   
     
     
         2 . The method of  claim 1 , wherein the two-dimensional image of the imaged object is obtained from an optical sensor. 
     
     
         3 . The method of  claim 1 , wherein correcting the calculated size of the imaged object includes increasing the calculated size when the separation distance is longer and decreasing the calculated size when the separation distance is shorter. 
     
     
         4 . The method of  claim 1 , wherein the separation distance to the imaged object is determined by identifying mismatch between the first digital sequence represented by the electromagnetic signal and the digital echo sequence in the digital echo signal. 
     
     
         5 . The method of  claim 1 , further comprising:
 determining an in-phase component of the digital echo signal;   determining an in-phase correlation value of the in-phase component of the digital echo signal; and   wherein correcting the calculated size of the imaged object is based on the separation distance that is determined and also is based on the in-phase correlation value.   
     
     
         6 . The method of  claim 1 , further comprising:
 determining a quadrature component of the digital echo signal;   determining a quadrature correlation value of the quadrature component of the echo signal,   wherein correcting the calculated size of the imaged object is based on the separation distance that is determined and also is based on the quadrature correlation value.   
     
     
         7 . The method of  claim 1 , further comprising:
 determining an in-phase component of the digital echo signal;   determining a quadrature component of the digital echo signal;   determining an in-phase correlation value of the in-phase component of the digital echo signal; and   determining a quadrature correlation value of the quadrature component of the echo signal,   wherein correcting the calculated size of the imaged object is based on the separation distance that is determined and also is based on the in-phase correlation value and the quadrature correlation value.   
     
     
         8 . A system comprising:
 one or more processors configured to obtain a two-dimensional image of an imaged object and to determine a calculated size of the imaged object from the two-dimensional image; and   one or more antennas configured to transmit an electromagnetic signal toward the imaged object, the electromagnetic signal representative of a first digital sequence and to receive an echo of the electromagnetic signal,   wherein the one or more processors also are configured to determine a separation distance to the imaged object by digitally comparing a digital echo signal that is representative of the echo with the first digital sequence that is represented by the electromagnetic signal, the one or more processors also configured to correct the calculated size of the imaged object that was determined using the separation distance.   
     
     
         9 . The system of  claim 8 , wherein the one or more processors are configured to obtain the two-dimensional image of the imaged object from an optical sensor. 
     
     
         10 . The system of  claim 8 , wherein the one or more processors are configured to correct the calculated size of the imaged object by increasing the calculated size when the separation distance is longer and decreasing the calculated size when the separation distance is shorter. 
     
     
         11 . The system of  claim 8 , wherein the one or more processors are configured to determine the separation distance to the imaged object by identifying mismatch between the first digital sequence represented by the electromagnetic signal and the digital echo sequence in the digital echo signal. 
     
     
         12 . The system of  claim 8 , wherein the one or more processors also are configured to determine an in-phase component of the digital echo signal and determine an in-phase correlation value of the in-phase component of the digital echo signal,
 wherein the one or more processors are configured to correct the calculated size of the imaged object based on the separation distance that is determined and also based on the in-phase correlation value.   
     
     
         13 . The system of  claim 8 , wherein the one or more processors also are configured to determine a quadrature component of the digital echo signal and determine a quadrature correlation value of the quadrature component of the echo signal,
 wherein the one or more processors are configured to correct the calculated size of the imaged object based on the separation distance that is determined and also based on the quadrature correlation value.   
     
     
         14 . The system of  claim 8 , wherein the one or more processors are configured to determine an in-phase component of the digital echo signal, determine a quadrature component of the digital echo signal, determine an in-phase correlation value of the in-phase component of the digital echo signal, and determine a quadrature correlation value of the quadrature component of the echo signal,
 wherein the one or more processors are configured to correct the calculated size of the imaged object based on the separation distance that is determined and also based on the in-phase correlation value and the quadrature correlation value.   
     
     
         15 . A method comprising:
 transmitting an electromagnetic waveform representative of a designated sequence of digital bits;   receiving one or more echoes of the waveform;   digitizing the one or more echoes that are received into an echo signal representative of an echo sequence of digital bits;   comparing different first and second portions of the echo sequence of digital bits with a coarse stage receive pattern of digital bits, the coarse stage receive pattern being a different sequence of digital bits than the designated sequence of digital bits represented by the electromagnetic waveform that was transmitted;   selecting the first portion of the echo sequence of digital bits as more closely matching the coarse stage receive pattern of digital bits than the second portion of the echo sequence of digital bits;   determining a time delay between a start of the echo sequence of digital bits and the first portion of the echo sequence of digital bits; and   determining a time of flight of the electromagnetic waveform that was transmitted using the time delay that is determined.   
     
     
         16 . The method of  claim 15 , wherein the coarse stage receive pattern is different from the designated sequence of digital bits represented by the electromagnetic waveform by the coarse stage receiving pattern having one or more of a different length of digital bits or a different sequence of digital bits. 
     
     
         17 . The method of  claim 15 , further comprising:
 generating a baseband echo signal based on the one or more echoes that were received, the baseband echo signal representing a fine stage receive pattern of digital bits;   temporally shifting the fine stage receive pattern of digital bits relative to the echo sequence of digital bits by the time delay that is determined;   determining an amount of overlap or an amount of mismatch between the fine stage receive pattern of digital bits are is temporally shifted with the baseband echo signal;   correlating the amount of overlap or the amount of mismatch with a time delay; and   modifying the time of flight that was determined by the time delay.   
     
     
         18 . The method of  claim 15 , further comprising:
 determining one or more of an in-phase component or a quadrature component of the echo signal;   determining an amount of overlap or an amount of mismatch between the echo sequence of digital bits and the one or more of the in-phase component or the quadrature component of the echo signal;   correlating the amount of overlap or the amount of mismatch with a time delay; and   modifying the time of flight that was determined by the time delay.   
     
     
         19 . The method of  claim 15 , further comprising:
 changing one or more of the first portion or the second portion of the echo sequence of digital bits by applying a receive pattern mask to the echo sequence of digital bits,   wherein comparing the different first and second portions of the echo sequence of digital bits includes comparing the one or more of the first portion or the second portion of the echo sequence of digital bits that was changed with the coarse stage receive pattern of digital bits.   
     
     
         20 . The method of  claim 15 , further comprising:
 generating a baseband echo signal based on the one or more echoes that were received, the baseband echo signal representing a fine stage receive pattern of digital bits;   temporally shifting the fine stage receive pattern of digital bits relative to the echo sequence of digital bits by the time delay that is determined;   determining a first amount of overlap or a first amount of mismatch between the fine stage receive pattern of digital bits are is temporally shifted with the baseband echo signal;   correlating the first amount of overlap or the first amount of mismatch with a first additional time delay;   determining one or more of an in-phase component or a quadrature component of the echo signal;   determining a second amount of overlap or a second amount of mismatch between the echo sequence of digital bits and the one or more of the in-phase component or the quadrature component of the echo signal;   correlating the second amount of overlap or the second amount of mismatch with an additional second time delay; and   modifying the time of flight that was determined by both the additional first time delay and the additional second time delay.