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# MSP430FR6047: Waveform Capture Based Ultrasonic Sensing Water Flow Metering Technology

Part Number: MSP430FR6047
Hi there,
Our company is planning to use MSP430FR6047 for ultrasonic water metering application and we appreciate it if you guys try to help us figure out the listed below questions ASAP;
1. The absolute time of flight (absToF) is determined by a two-stage process, namely Acquisition, and tracking, The question at hand is: How does the tracking algorithm determine whether a signal is arriving or not and whether it is the same as a prior signal?
2. how to select the effective Toffset value?
3. Please attach a reference textbook that describes the correlationinterpolation, and time of flight calculation algorithms in depth.

• Hi,

https://www.ti.com/lit/an/slaa889a/slaa889a.pdf

Thanks!

Best Regards

Johnson

• Hi Johnson,

Thank you. But, I reviewed all of the documents from Texas Instruments on this subject, but I couldn't find any paper that explains everything in depth, which is why I asked here. I really need a reference textbook or someone who can explain the calculation in depth.

• Hi Ashenafi,

Below is the thoery:

Step1: Search all peak point.

Step2: Do some interpolation to get the curve

Step3: we can find the Toffset based on threashold

Thanks!

Best Regards

Johnson

• Hi Johnson,

Thanks, But what I want to know is;

1. why didn't the Toffset range start from zero? from the graph, it starts from around 0.5 microseconds.

2. how to get/set the threshold?

3. The absolute time of flight (absToF) is determined by a two-stage process, namely Acquisition, and tracking, The question at hand is: How does the tracking algorithm determine whether a signal is arriving or not and whether it is the same as a prior signal?

please try to elaborate on all the questions thoroughly.

• Hi Ashenafi,

For AbsTOF, include those items:

1. Pulse time Tp
3. From ADC capture to threshold time -> Toffset

Thus the AbsTOF = Tadc-Tp+Toffset.

And actuall,  dTOF accuracy will have the greatest impact for measurement accuracy, not AbsTOF.

How to select a good threshold:

We set11% of the peak point as the threshold default. In fact, the best point should be the peak point, that point have a large gap with the former and the latter.

Thanks!

Best Regards

Johnson

• Hi Johnson,

Thanks, Can you please say something about question number 1 and 3?

• Hi Ashenafi,

Thanks!

Best Regards

Johnson

• Hi Johnson,

Thank you, but I appreciate if you can explain question number 3.

• Hi Ashenafi,

Thanks!

Best Regards

Johnson

• Hi Johnson,

Okay Thanks

• Hi Johnson,

Can you please relate the formula that you mention above on the image and the formula in the attached image below?

• Hi Ashenafi,

Tnis formula report the method to calculate actual AbsTOF:

From the pulse sent out to transduce(T1), till got the waveform n*peak point(T2), this is Tprop.

Then there are alos have a time named: Tupscorr, this is calculated by Lobe algorithm.

Then the AbsTof is means that from first pulse sent out to get the first pulse:

Thanks!

Best Regards

Johnson

• Hi Johnson

Thank you for your response.

However, in the paper below that you previously sent, you added the Toffset, but it is subtracted in the Ti document which is discussed above and I got confused. So, could you please explain these two?

• Hi Ashenafi,

The picture I drew is based on some naming inside the USS code, so it will be different from the actual document. Please follow the description of the document.

Thanks!

Best Regards

Johnson

• Hi Johnson,

Ok

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