Flow measurement by combining 3L echo with delta time-of-flight cross correlation

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.

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.