Ultrasonic ranging system and method for improving accuracy thereof
First Claim
1. A method of measuring distance to a target using ultrasonic sound waves, said method comprising the steps of:
- generating an electrical drive signal having a series of signal pulses at an ultrasonic frequency;
applying said drive signal as an input to an ultrasonic transducer to produce ultrasonic sound waves;
transmitting said ultrasonic sound waves in a desired transmission path;
receiving ultrasonic sound waves reflected from a target in the transmission path of said transmitted sound waves;
converting said received reflected sound waves to an electrical signal;
determining a middle time value of the drive signal;
determining a middle time value of the received electrical signal;
determining a time period from the middle time value of the received electrical signal to the middle time value of the drive signal; and
determining distance to the target as a function of one-half of said time period and speed of travel of said ultrasonic sound waves.
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Accused Products
Abstract
An ultrasonic ranging system and method for detecting the presence of and distance to a target using ultrasonic sound waves generated by an ultrasonic transducer with reduced audible noise. Electrical ultrasonic signal pulses are modulated according to a smooth modulation envelope and a transducer drive signal is generated from the modulated signal pulses. The transducer drive signal drives an ultrasonic transducer which generates ultrasonic sound waves for transmission in a desired path, and further receives ultrasonic sound waves reflected from targets in the transmission path. The received ultrasonic sound waves are converted to an electrical signal that is processed by a processor to provide time and distance information to the target. The distance information is computed by using a middle time value for the transmitted and received signals.
20 Citations
13 Claims
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1. A method of measuring distance to a target using ultrasonic sound waves, said method comprising the steps of:
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generating an electrical drive signal having a series of signal pulses at an ultrasonic frequency;
applying said drive signal as an input to an ultrasonic transducer to produce ultrasonic sound waves;
transmitting said ultrasonic sound waves in a desired transmission path;
receiving ultrasonic sound waves reflected from a target in the transmission path of said transmitted sound waves;
converting said received reflected sound waves to an electrical signal;
determining a middle time value of the drive signal;
determining a middle time value of the received electrical signal;
determining a time period from the middle time value of the received electrical signal to the middle time value of the drive signal; and
determining distance to the target as a function of one-half of said time period and speed of travel of said ultrasonic sound waves. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An ultrasonic ranging system comprising:
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a drive signal generator for producing an electrical drive signal having a series of signal pulses at an ultrasonic frequency;
an ultrasonic transducer for converting said electrical drive signal to ultrasonic sound waves and for transmitting said ultrasonic sound waves in a desired transmission path, said ultrasonic transducer further receiving ultrasonic sound waves reflected from a target in said transmission path and converting said received reflected sound waves to an electrical signal; and
a processor for processing said drive signal and said received electrical signal and producing a distance measurement to said target, wherein said processor computes a middle time value of said drive signal and a middle time value of said received electrical signal and determines a time period between said middle time values, and computes the distance measurement as a function of said time period. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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Specification