Method and system for fluid flow rate measurement

1. A method of measuring fluid flow parameters of fluids flowing through lumens, the method comprising:

transmitting through a fluid flowing through a lumen, by a first transducer of a sensor secured to a structure defining the lumen, a plurality of transmit (TX) signals, each of the plurality of TX signals transmitted with a respective time delay from a clock signal of an analog-to-digital converter;

receiving, by a second transducer of the sensor, a plurality of receive (RX) signals, each one corresponding to a respective one of the plurality of transmitted TX signals;

sampling, by the analog-to-digital converter, at a first sampling rate, the plurality of RX signals received by the second transducer;

generating, by a processor, a fine resolution signal using sampled versions of the plurality of RX signals generated by the analog-to-digital converter, the fine resolution signal associated with a second sampling rate higher than the first sampling rate;

computing, by the processor, a cross-correlation signal indicative of cross-correlation between the fine resolution signal and a reference waveform; and

determining, by the processor, an estimate of a fluid flow parameter of the fluid based on the computed cross-correlation signal.

2. The method of claim 1 , wherein the fluid flow parameter includes fluid flow rate or fluid flow velocity.

3. The method of claim 1 , wherein the plurality of TX signals are transmitted with distinct jitter delays with respect to periods of the clock signal of the analog-to-digital converter.

4. The method of claim 3 , wherein determining an estimate of the fluid flow parameter includes:

determining, by the processor, multiple first estimates of the fluid flow parameter based on the plurality of RX signals corresponding to the TX signals transmitted with distinct jitter delays with respect to the periods of the clock signal of the analog-to-digital converter; and

generating, by the processor, a final estimate of the fluid flow parameter by averaging the multiple first estimates.

5. The method of claim 1 , wherein generating a fine resolution signal includes up-sampling a signal associated with the sampled versions of the plurality of RX signals, the up-sampling includes applying interpolation using a truncated sinc function.

6. The method of claim 1 , wherein the plurality of TX signals are transmitted with distinct incremental delays with respect to periods of the clock signal of the analog-to-digital converter.

7. The method of claim 6 , wherein generating the fine resolution signal includes interleaving samples of the plurality of RX signals corresponding to the plurality of TX signals transmitted with distinct incremental delays with respect to the periods of the clock signal of the analog-to-digital converter.

8. The method of claim 7 , wherein generating the fine resolution signal further includes up-sampling an interleaved signal generated by interleaving the samples of the plurality of RX signals corresponding to the plurality of TX signals transmitted with distinct incremental delays with respect to the periods of the clock signal of the analog-to-digital converter.

9. The method of claim 1 , wherein the reference waveform is associated with a RX signal received by the first transducer responsive to transmitting a TX signal by the second transducer.

10. The method of claim 1 , wherein the reference waveform represents a signal component associated with the plurality of TX signals.

11. The method of claim 1 , wherein the reference waveform is associated with a zero-flow RX signal.

12. The method of claim 1 , wherein computing the cross-correlation signal includes:

computing a first cross-correlation signal between a first reference waveform and a signal associated with the sampled versions of the plurality of RX signals, the first reference waveform different from the reference waveform and the first cross-correlation signal different from the cross-correlation signal;

determining a time window based on the first cross-correlation signal; and

computing the cross-correlation signal by computing a plurality of cross-correlation values within the time window indicative of cross-correlations between the reference waveform and the fine resolution signal.

13. The method of claim 12 , wherein determining the time window includes:

determining a first reference point associated with the first cross-correlation signal; and

determining a second reference point associated with the cross-correlation signal based on the first reference point; and

determining the time window based on the second reference point.

14. The method of claim 12 , wherein samples of the first reference waveform that are less than a threshold value are nullified.

15. The method of claim 12 , wherein the signal associated with the sampled versions of the plurality of RX signals includes at least one of:

a sampled version of a RX signal of the plurality of RX signals;

an up-sampled version of a RX signal of the plurality of RX signals;

an interleaved version of the sampled versions of plurality of RX signals; and

the fine resolution signal.

16. The method of claim 12 further comprising:

locating, by the processor, a maximum cross-correlation value of the plurality of cross-correlation values within the time window;

in response to locating the maximum cross-correlation value at a boundary point of the time window, shifting the time window towards that boundary point; and

in response to locating the maximum cross-correlation value inside the time window, determining a second time delay between the reference waveform and the fine resolution signal using a location of the maximum cross-correlation inside the time window.

17. The method of claim 16 , wherein locating a maximum cross-correlation value inside the time window includes applying a ternary search process.

18. The method of claim 16 comprising:

determining, by the processor, the estimated fluid flow parameter based on the time delay between the reference waveform and the fine resolution signal.

19. The method of claim 18 comprising:

determining, by the processor, the estimated fluid flow parameter based on the time delay between the reference waveform and the fine resolution signal using a lookup table.

20. The method of claim 1 comprising:

determining, by the processor, multiple estimates of the fluid flow parameter based on downstream and up-stream RX signals.