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EVM430-FR6047: About UPS and DNS Gap

M_K_T
Prodigy 160 points

Part Number: EVM430-FR6047

I would like to confirm something about UPS and DNS Gap.

I am aware that if this value is too small, the UPS echoes will remain as noise and affect the DNS waveform, am I right?

We did an experiment to see how this difference would affect the waveforms by varying the value of UPS and DNS Gap from 100us to 2000us and checked the ADCcapture. However, there was no significant change in any of the waveforms. Does this mean that at 100us, the ultrasonic waves are sufficiently attenuated and no longer have any effect? Or is the noise removed by the software?

In general, how long does it take for the ultrasonic signal from a 1 MHz transducer to attenuate and become less affected by noise?

Thank you in advance for your time.

  • +1
    TI__Genius 10060 points
    M_K_T said:
    I am aware that if this value is too small, the UPS echoes will remain as noise and affect the DNS waveform, am I right?

    Yes

    M_K_T said:
    We did an experiment to see how this difference would affect the waveforms by varying the value of UPS and DNS Gap from 100us to 2000us and checked the ADCcapture. However, there was no significant change in any of the waveforms. Does this mean that at 100us, the ultrasonic waves are sufficiently attenuated and no longer have any effect? Or is the noise removed by the software?

    If you are seeing clean data for both UPS and DNS data then there is probably no cross stimulation issues. You should be able to tell how long it take for the pulse to decay by looking at the ADC capture in the GUI. 

    M_K_T said:
    In general, how long does it take for the ultrasonic signal from a 1 MHz transducer to attenuate and become less affected by noise?

    I don't have an exact number for this since it will depend on the pipe, transducer, and drive strength. Like I noted above, you can get a good idea based on the pulse decay.

    Regards,

    Evan

  • 0 in reply to Evan Lew
    Prodigy 160 points

    Thank you for your answer Evan.
    Let me ask one last question.

    I am aware that the smaller the value, the more accurate the measurement, as long as it is confirmed that the noise due to reflection does not affect the waveform. Am I right in my thinking?
    For example, if it is confirmed that the ultrasound is completely attenuated at 900us, is it possible that setting it at 1000us is more accurate than setting it at 2000us or 3000us?

    Also, I am very sorry, but I would like to prevent my name from being found in searches. If you post your name in a reply, could you please use your initials instead of your first name, etc.?

  • +1 in reply to M_K_T
    TI__Genius 10060 points

    I would think that minimizing the time between the DNS and UPS sampling would be the most accurate, however I'm not sure how much it matters in practice. I would suggest giving your design a bit of margin in case the the reflections change in different scenarios (pipe material, temperature, etc.)

    Regards,

    EL

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