# US 2021/0333390 A1 · Method and system for ultrasound time-of-flight measurement > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0333390 A1 - Document ID: US20210333390A1 - Status: Published application - Kind: A1 - Application number: 17/367,383 - Filed: 2021-07-04 - Published: 2021-10-28 - Earliest claimed: 2015-08-17 - Assignees: Texas Instruments Incorporated - Applicants: Texas Instruments Incorporated - Inventors: Yuming Zhu; Srinath Ramaswamy; Domingo Garcia; Sujeet Milind Patole - Web page: https://patentgrep.com/patent/US20210333390A1 ## CPC - G01S 15/10: using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurement G01S15/32) - G01N 29/07: by measuring propagation velocity or propagation time of acoustic waves - G01N 29/075: {by measuring or comparing phase angle (measuring frequencies or phase angles per se G01R23/00, G01R25/00)} - G01N 29/11: by measuring attenuation of acoustic waves - G01N 29/12: by measuring frequency or resonance of acoustic waves {(measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00)} - G01N 29/14: using acoustic emission techniques {(echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00)} - G01S 7/539: using analysis of echo signal for target characterisation; Target signature; Target cross-section - G01S 15/582: {using transmission of interrupted pulse-modulated waves and based upon the Doppler effect resulting from movement of targets} - G01N 2291/011: Velocity or travel time - G01N 2291/014: Resonance or resonant frequency - G01N 2291/0258: Structural degradation, e.g. fatigue of composites, ageing of oils - G01S 15/003: {Bistatic sonar systems; Multistatic sonar systems} - 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 - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A transducer system with transducer and circuitry for applying a pulse train at a single frequency to excite the transducer. The transducer is operable to receive an echo waveform in response to the pulse train. The system also comprises circuitry for determining a time of flight as between a first reference time associated with the pulse train and a second reference time associated with the echo waveform. ## Claims ### Claim 1 A method comprising: receiving a set of samples associated with an echo waveform; determining an amplitude envelope of the echo waveform using the set of samples; determining a threshold crossing time based on the amplitude envelope crossing a threshold; identifying a subset of the set of samples proximate in time to the threshold crossing time; determining a phase of each sample in the subset; performing a line fit on the phases of the samples in the subset to determine a zero phase time of the echo waveform proximate to the threshold crossing time; and determining a time of flight associated with the echo waveform using the zero phase time proximate to the threshold crossing time. ### Claim 2 (depends on 1) The method of claim 1, wherein the determining of the zero phase time proximate to the threshold crossing time includes determining whether the threshold crossing time is closer to: a first zero phase crossing time in a same cycle as the threshold crossing time, a second zero phase crossing time in a cycle prior to the threshold crossing time, or a third zero phase crossing time in a cycle after the threshold crossing time. ### Claim 3 (depends on 1) The method of claim 1 further comprising determining a fractional portion of the threshold crossing time based on a difference between the threshold crossing time and a time of a nearest sample of the set of samples, wherein the determining of the zero phase time proximate to the threshold crossing time includes determining, based on the fractional portion of the threshold crossing time, whether the threshold crossing time is closer to: a first zero phase crossing time in a same cycle as the threshold crossing time, a second zero phase crossing time in a cycle prior to the threshold crossing time, or a third zero phase crossing time in a cycle after the threshold crossing time. ### Claim 4 (depends on 1) The method of claim 1, wherein the time of flight is between a first reference time associated with a set of pulses used to excite a transducer and the zero phase time. ### Claim 5 (depends on 4) The method of claim 4, wherein the first reference time is a time of a first pulse transition in the set of pulses. ### Claim 6 (depends on 4) The method of claim 4 further comprising providing the set of pulses to the transducer. ### Claim 7 (depends on 1) The method of claim 1 further comprising converting each sample of the set of samples into an (I,Q) sample pair, wherein the determining of the amplitude envelope of the echo waveform is based a square root of a square of the respective (I,Q) sample pair of each sample in the set of samples. ### Claim 8 (depends on 1) The method of claim 1 further comprising converting each sample of the set of samples into an (I,Q) sample pair, wherein the determining of the phase of each sample in the subset is based on the respective (I,Q) sample pair. ### Claim 9 (depends on 1) The method of claim 1, wherein: the echo waveform is associated with a target; and the method further includes determining a distance between a transducer and the target based on the time of flight. ### Claim 10 A system comprising: an analog-to-digital converter configured to receive an electrical signal associated with an echo waveform and to produce a set of samples associated with the echo waveform in response to the electrical signal; and a processor coupled to the analog-to-digital converter and configured to: receive the set of samples from the analog-to-digital converter; determine an amplitude envelope based on the set of samples; determine a threshold crossing time for the amplitude envelope; identify a subset of the set of samples proximate in time to the threshold crossing time; determine a phase of each sample in the subset; perform a line fit on the phases of the samples in the subset to determine a zero phase time of the echo waveform proximate to the threshold crossing time; and determine a time of flight associated with the echo waveform using the zero phase time proximate to the threshold crossing time. ### Claim 11 (depends on 10) The system of claim 10, wherein the processor is configured to determine the zero phase time proximate to the threshold crossing time by determining whether the threshold crossing time is closer to: a first zero phase crossing time in a same cycle as the threshold crossing time, a second zero phase crossing time in a cycle prior to the threshold crossing time, or a third zero phase crossing time in a cycle after the threshold crossing time. ### Claim 12 (depends on 10) The system of claim 10, wherein the processor is configured to determine the zero phase time proximate to the threshold crossing time by: determining a fractional portion of the threshold crossing time based on a difference between the threshold crossing time and a time of a nearest sample of the set of samples; and determining, based on the fractional portion of the threshold crossing time, whether the threshold crossing time is closer to: a first zero phase crossing time in a same cycle as the threshold crossing time, a second zero phase crossing time in a cycle prior to the threshold crossing time, or a third zero phase crossing time in a cycle after the threshold crossing time. ### Claim 13 (depends on 10) The system of claim 10, wherein the time of flight is between a first reference time associated with a set of pulses used to excite a transducer and the zero phase time. ### Claim 14 (depends on 13) The system of claim 13, wherein the first reference time is a time of a first pulse transition in the set of pulses. ### Claim 15 (depends on 13) The system of claim 13 further comprising a transceiver that includes: the transducer coupled to the processor, wherein the processor is configured to provide the set of pulses to the transducer; and a receiver coupled to the analog-to-digital converter to provide the electrical signal. ### Claim 16 (depends on 10) The system of claim 10, wherein the processor includes: a bandpass filter coupled to the analog-to-digital converter and configured to: receive the set of samples; and provide, for each sample of the set of samples, an in-phase component of an (I,Q) sample pair; and a Herbert filter coupled to the bandpass filter and configured to provide for each sample of the set of samples, quadrature component of the (I,Q) sample pair; and an amplitude detection block coupled to the bandpass filter and to the Herbert filter and configured to determine the amplitude envelope based on the (I,Q) sample pairs of the set of samples. ### Claim 17 (depends on 10) The system of claim 10, wherein the processor includes: a bandpass filter coupled to the analog-to-digital converter and configured to: receive the set of samples; and provide, for each sample of the set of samples, an in-phase component of an (I,Q) sample pair; a Herbert filter coupled to the bandpass filter and configured to provide for each sample of the set of samples, quadrature component of the (I,Q) sample pair; and a phase angle detection block coupled to the bandpass filter and to the Herbert filter and configured to determine the phase of each sample in the subset based on the respective (I,Q) sample pair. ### Claim 18 (depends on 10) The system of claim 10, wherein: the echo waveform is associated with a target; and the processor is configured to determine a distance between a transducer and the target based on the time of flight.