# US 11,906,338 B2 · Flow measurement by combining 3L echo with delta time-of-flight cross correlation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,906,338 B2 - Document ID: US11906338B2 - Status: Granted - Kind: B2 - Application number: 17/188,645 - Filed: 2021-03-01 - Published: 2021-12-09 - Granted: 2024-02-20 - Earliest claimed: 2020-06-05 - Assignees: Honeywell International Inc. - Applicants: Honeywell International Inc. - Inventors: Tobias Meimberg; Christian Lampe-Jürgens; Ralf Heinrich Schröder genannt Berghegger; Andreas Wuchrer - Web page: https://patentgrep.com/patent/US11906338B2 ## CPC - G01F 1/662: {Constructional details} - G01F 1/668: {Compensating or correcting for variations in velocity of sound} - G01F 1/661: using light - G01F 1/666: {by detecting noise and sounds generated by the flowing fluid} - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME ## Abstract Methods and systems for flow measurement can involve calculating an absolute-time-of-flight with respect to a flow of a fluid in a flow channel by reflected signals, reflected and unreflected signals, or a pulse train, determining a delta-time-of-flight with a cross correlation of two signals with respect to the flow of the fluid in the flow channel, and calculating the flow rate of the flow of the fluid in the flow channel based on the absolute-time-of-flight and the cross correlation of the delta-time-of-flight. ## Claims ### Claim 1 A method for flow measurement in a flow channel associated with a first transducer and a second transducer, the method, comprising: calculating an absolute-time-of-flight with respect to a flow of a fluid in the flow channel by reflected signals, reflected and unreflected signals, or a pulse train; determining a delta-time-of-flight with a cross correlation of two signals with respect to the flow of the fluid in the flow channel; and calculating a flow rate of the flow of the fluid in the flow channel based on the absolute-time-of-flight and the delta-time-of-flight, wherein calculating the flow rate of the flow of the fluid in the flow channel comprises measuring the absolute-time-of-flight of 3×length between the first transducer and the second transducer and subtracting the absolute-time-of-flight of 1×length between the first transducer and the second transducer, to eliminate electrical and acoustic delays and wherein measuring the absolute-time-of-flight of 3L between the first transducer and the second transducer includes dividing 2×length (2L) between the first transducer and the second transducer by a first term ‘c+v’, and dividing 1×length between the first transducer and the second transducer by a second term ‘c−v’, and wherein the first term and the second term are based on a speed of sound and a medium velocity of the fluid in the flow channel. ### Claim 2 (depends on 1) The method of claim 1 wherein calculating the flow rate of the flow of the fluid based on the absolute-time-of-flight and the cross correlation of the delta-time-of-flight, further comprises: calculating the flow rate of the flow of the fluid based on the absolute-time-of-flight measured upstream and downstream in the flow channel, and the delta-time-of-flight. ### Claim 3 (depends on 2) The method of claim 2 wherein the absolute-time-of-flight measured upstream and the absolute-time-of-flight measured downstream are used to calculate the delta-time-of-flight and/or the flow rate. ### Claim 4 (depends on 2) The method of claim 2 wherein different acoustic paths comprise different input signals with different gains or output signals with different gains. ### Claim 5 (depends on 1) The method of claim 1 wherein calculating the absolute-time-of-flight with respect to the flow of the fluid in the flow channel by reflected signals, reflected signals, reflected and unreflected signals, or the pulse train, further comprises: measuring the absolute-time-of-flight with respect to the flow of the fluid in the flow channel across a first acoustic path of the flow channel from the first transducer to the second transducer to determine a first absolute-time-of-flight; and measuring the absolute-time-of-flight with respect to the flow of the fluid in the flow channel across a second acoustic path of the flow channel from the first transducer to the second transducer to determine a second absolute-time-of-flight, and calculating a third absolute-time-of-flight by the difference between the first absolute-time-of-flight and the second absolute-time-of-flight. ### Claim 6 (depends on 5) The method of claim 5 wherein: an acoustic path including the first acoustic path or the second acoustic path comprises reflected or reflected and unreflected signals between the first transducer and the second transducer. ### Claim 7 (depends on 1) The method of claim 1 wherein the reflected signals, the reflected and unreflected signals or the pulse train comprise at least one of: ultrasound; acoustic sound; or light. ### Claim 8 (depends on 7) The method of claim 7 wherein the absolute-time-of-flight is used to calculate the speed of sound by dividing a length of the acoustic path with the absolute-time-of-flight. ### Claim 9 (depends on 1) The method of claim 1 wherein the flow channel is associated with a gas meter comprising an ultrasonic gas meter. ### Claim 10 A system for flow measurement, comprising: a gas meter having a first transducer, a second transducer, and a flow channel between the first transducer and the second transducer, wherein: an absolute-time-of-flight with respect to a flow of a fluid in the flow channel is calculated by reflected signals, reflected and unreflected signals, or a pulse train; a delta-time-of-flight with respect to the flow of the fluid in the flow channel is determined with a cross correlation of two signals; and a flow rate of the flow of the fluid in the flow channel is calculated based on the absolute-time-of-flight and the delta time-of-flight, wherein calculating the flow rate of the flow of the fluid in the flow channel comprises measuring the absolute-time-of flight of 3×length between the first transducer and the second transducer and subtracting the absolute-time-of-flight of 1×length between the first transducer and the second transducer, to eliminate the electrical and acoustic delays and wherein measuring the absolute-time-of-flight of 3L between the first transducer and the second transducer includes dividing 2×length (2L) between the first transducer and the second transducer by a first term ‘c+v’, and dividing 1×length between the first transducer and the second transducer by a second term ‘c−v’, and wherein the first term and the second term are based on a speed of sound and a medium velocity of the fluid in the flow channel. ### Claim 11 (depends on 10) The system of claim 10 wherein the flow rate of the flow of the fluid is calculated based on the absolute-time-of-flight measured upstream and downstream in the flow channel, and the delta-time-of-flight. ### Claim 12 (depends on 11) The system of claim 11 wherein the absolute-time-of-flight measured upstream and the absolute-time-of-flight measured downstream are used to calculate the delta-time-of-flight and/or the flow rate. ### Claim 13 (depends on 11) The system of claim 11 wherein different acoustic paths comprise different input signals with different gains or output signals with different gains. ### Claim 14 (depends on 10) The system of claim 10 wherein: the absolute-time-of-flight is measured with respect to the flow of the fluid in the flow channel across a first acoustic path of the flow channel from the first transducer to the second transducer to determine a first absolute-time-of-flight; the absolute-time-of-flight with respect to the flow of the fluid in the flow channel is measured across a second acoustic path of the flow channel from the first transducer to the second transducer to determine a second absolute-time-of-flight and calculating a third absolute-time-of-flight by the difference between the first absolute-time-of-flight and the second absolute-time-of-flight. ### Claim 15 (depends on 14) The system of claim 14 wherein: an acoustic path including the first acoustic path or the second acoustic path comprises reflected or reflected and unreflected signals between the first transducer and the second transducer. ### Claim 16 (depends on 10) The system of claim 10 wherein the reflected signals, the reflected and unreflected signals or the pulse train comprise at least one of: ultrasound; acoustic sound; or light. ### Claim 17 (depends on 16) The system of claim 16 wherein the absolute-time-of-flight is used to calculate the speed of sound by dividing a length of the acoustic path with the absolute-time-of-flight. ### Claim 18 A system for flow measurement, comprising: at least one processor; and a non-transitory computer-usable medium embodying computer program code, said computer-usable medium capable of communicating with the at least one processor, the computer program code comprising instructions executable by the at least one processor and configured for: calculating an absolute-time-of-flight with respect to a flow of a fluid in a flow channel by reflected signals, reflected and unreflected signals, or a pulse train; determining a delta-time-of-flight with a cross correlation of two signals with respect to the flow of the fluid in the flow channel; and calculating a flow rate of the flow of the fluid in the flow channel based on the absolute-time-of-flight and the delta-time-of-flight, wherein calculating the flow rate of the flow of the fluid in the flow channel includes measuring the absolute-time-of-flight of 3×length between the first transducer and the second transducer, and then subtracting the absolute-time-of-flight of 1×length between the first transducer and the second transducer, to eliminate the electrical and acoustic delays and wherein measuring the absolute-time-of-flight of 3L between the first transducer and the second transducer includes dividing 2×length (2L) between the first transducer and the second transducer by a first term ‘c+v’, and dividing 1×length between the first transducer and the second transducer by a second term ‘c−v’, and wherein the first term and the second term are based on a speed of sound and a medium velocity of the fluid in the flow channel. ### Claim 19 (depends on 18) The system of claim 18 wherein the instructions for calculating the absolute-time-of-flight with respect to the flow of the fluid in the flow channel by reflected signals, reflected signals, reflected and unreflected signals, or a pulse train, are further configured for: calculating the flow rate of the flow of the fluid based on the absolute-time-of-flight measured upstream and downstream in the flow channel, and the delta-time-of-flight. ### Claim 20 (depends on 18) The system of claim 18 wherein the instructions for measuring the absolute-time-of-flight with respect to the flow of the fluid in the flow channel, are further configured for: measuring the absolute-time-of-flight with respect to the flow of the fluid in the flow channel across a first acoustic path of the flow channel from the first transducer to the second transducer to determine a first absolute-time-of-flight; and measuring the absolute-time-of-flight with respect to the flow of the fluid in the flow channel across a second acoustic path of the flow channel from the first transducer to the second transducer to determine a second absolute-time-of-flight, and calculating a third absolute-time-of-flight by the difference between the first absolute-time-of-flight and the second absolute-time-of-flight.