# US 2022/0035031 A1 · Time-varying template for improved short-distance performance in coded ultrasonic ranging

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- Number: US 2022/0035031 A1
- Document ID: US20220035031A1
- Status: Published application
- Kind: A1
- Application number: 17/503,407
- Filed: 2021-10-18
- Published: 2022-02-03
- Earliest claimed: 2019-11-25
- Assignees: Texas Instruments Incorporated
- Applicants: Texas Instruments Incorporated
- Inventors: LEI DING; SRINATH MATHUR RAMASWAMY; ANAND GOPALAN
- Web page: https://patentgrep.com/patent/US20220035031A1

## CPC

- G01S 15/931: of land vehicles
- B25J 19/026: {Acoustical sensing devices}
- G01S 3/808: using transducers spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
- G01S 7/524: Transmitters
- G01S 7/527: Extracting wanted echo signals {(Doppler systems G01S15/50)}
- G01S 15/102: {using transmission of pulses having some particular characteristics}
- G01S 15/325: {using transmission of coded signals, e.g. of phase-shift keyed [PSK] signals}
- G01S 15/582: {using transmission of interrupted pulse-modulated waves and based upon the Doppler effect resulting from movement of targets}
- G01S 15/87: Combinations of sonar systems
- G02B 7/40: using time delay of the reflected waves, e.g. of ultrasonic waves
- G01S 15/104: {wherein the transmitted pulses use a frequency- or phase-modulated carrier wave}
- G01S 2015/938: {in the bumper area}
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- B25J: MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES ({manipulators specially adapted for use in surgery A61B34/70; manipulators used in cleaning hollow articles B08B9/04}; manipulators associated with rolling mills B21B39/20; manipulators associated with forging machines B21J13/10; {manipulators associated with picking-up and placing mechanisms B23P19/007}; means for holding wheels or parts thereof B60B30/00; {vehicles with ground-engaging propulsion means, e.g. walking members B62D57/02, B62D57/032; devices for picking-up and depositing articles or materials between conveyors B65G47/90, B65G47/91; manipulators with gripping or holding means for transferring packages B65H67/065}; cranes B66C; {manipulators used in the protection or supervision of pipe-line installations F17D5/00; walking equipment adapted for nuclear steam-generators F22B37/006}; manipulators specially adapted for, or associated with, nuclear reactors G21C; {apparatus used for handling wafers during manufacture or treatment of semiconductor H10P72/50})
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

Ultrasonic ranging systems and methods that emit coded bursts and correlate transduced acoustical echoes of the bursts with a receive template characterizing a burst code to determine time-of-flight information use receive templates of time-variable length to improve short-range object detection. The template length is based on a time index measured from the start of the burst emission. The detection can account for a dead zone of transducer ringing following a burst. A time-variable gain that is also based on the time index can be applied to the correlated signal. The length and gain can be adjusted with reduced temporal frequency to reduce computation cost.

## Claims

### Claim 1

An ultrasonic ranging system comprising:
time-varying template generation circuitry configured to generate a time-varying coded receive template based on a full-length template and a time index from a start of a burst signal provided to an ultrasonic transducer, the length of the time-varying coded receive template depending on the time index; and
correlator circuitry coupled to the time-varying template generation circuitry and configured to correlate a received transduced reflected signal with the time-varying coded receive template to produce a correlated signal, an envelope of the correlated signal containing a peak indicative of a distance between the ultrasonic transducer and a detected object.

### Claim 2 (depends on 1)

The system of claim 1, further comprising a time-varying gain multiplier coupled to the correlator circuitry and configured to adjust a gain of the correlated signal in an amount that is based on the time index from the start of the burst signal.

### Claim 3 (depends on 1)

The system of claim 1, the time-varying template generation circuitry being configured to generate the time-varying coded receive template further based on a programmable dead zone duration parameter indicative of a period of transducer ringing that follows the end of the burst signal.

### Claim 4 (depends on 1)

The system of claim 1, the time-varying template generation circuitry being configured to re-generate the time-varying coded receive template with a frequency that is less than once every sample.

### Claim 5

A method of ultrasonic ranging comprising:
emitting from an ultrasonic transducer a coded ultrasonic acoustic burst signal coded with a code;
transducing, by the ultrasonic transducer or another ultrasonic transducer, a reflected acoustic signal coded with the code;
generating a time-varying receive template characterizing the code, the length of the receive template being based on a time index measured from the start of emission of the burst signal;
correlating the transduced reflected acoustic signal with the time-varying receive template to produce a correlated signal; and
computing, based on the correlated signal, a time of flight of the reflected acoustic signal, the time of flight being indicative of a distance between the ultrasonic transducer and a detected object.

### Claim 6 (depends on 5)

The method of claim 5, the time-varying receive template being generated further based on a full-length template that is resampled from a coded excitation signal at point prior to its transduction into the coded ultrasonic acoustic burst signal.

### Claim 7 (depends on 5)

The method of claim 5, further comprising adjusting a gain of the correlated signal based on the time index.

### Claim 8

An ultrasonic detection system comprising:
excitation circuitry configured to induce an ultrasonic transducer to emit a coded ultrasonic acoustic burst signal, coded with a code;
listening circuitry configured to the receive from the ultrasonic transducer or another ultrasonic transducer a transduced reflected acoustic signal coded with the code;
a time-varying template generator configured to generate a time-varying receive template characterizing the code, based on a time index measured from the start of emission of the burst signal;
a correlator coupled to the listening circuitry and to the time-varying template generator and configured to correlate the transduced reflected signal with the time-varying receive template to produce a correlated signal; and
time-of-flight circuitry coupled to the correlator and configured to compute a time of flight of the reflected acoustic signal based on the correlated signal, the time of flight being indicative of a distance between the ultrasonic transducer and a detected object;
the time-varying template generator being configured to generate the time-varying receive template further based on a full-length template that is generated by sampling acoustic output of the coded ultrasonic acoustic burst signal including a period of transducer ringing that follows the end of the acoustic burst signal.

### Claim 9

An ultrasonic detection system comprising:
excitation circuitry configured to induce an ultrasonic transducer to emit a coded ultrasonic acoustic burst signal, coded with a code;
listening circuitry configured to the receive from the ultrasonic transducer or another ultrasonic transducer a transduced reflected acoustic signal coded with the code;
a time-varying template generator configured to generate a time-varying receive template characterizing the code, based on a time index measured from the start of emission of the burst signal;
a correlator coupled to the listening circuitry and to the time-varying template generator and configured to correlate the transduced reflected signal with the time-varying receive template to produce a correlated signal;
time-of-flight circuitry coupled to the correlator and configured to compute a time of flight of the reflected acoustic signal based on the correlated signal, the time of flight being indicative of a distance between the ultrasonic transducer and a detected object; and
a time-varying gain multiplier coupled between the correlator and the time-of-flight circuitry and configured to adjust a gain of the correlated signal based on the time index.