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Original question:

MSP430FR6047: there is a problem with the ultrasonic echo signal captured by the ADC

MSP430FR6047: USS echo signals in water pipe

Paolo Costantini
Prodigy 20 points
Part Number: MSP430FR6047

Tool/software:

Hi,

I have a question related to USS signal echo captured by MSP430FR6047

If I extend sampling window, I notice the reported additional signal after the useful signal.

Sometimes the additional signal merges in the final part of useful signal, so it becomes difficult to distinguish them.

Do you have any idea of ​​the possible causes? Is this an echo phenomenon?

Could this be a problem for the acquisition accuracy?

How can the phenomenon be eliminated/reduced?

Thank you so much.

  • 0
    TI__Mastermind 19787 points

    Hi, 

    Paolo Costantini said:
    signal echo captured by MSP430FR6047

    Setting sampling time too long can cause this problem.

    Paolo Costantini said:
    Sometimes the additional signal merges in the final part of useful signal, so it becomes difficult to distinguish them.

    The ultrasonic emission time is too long which can cause this problem.

    Paolo Costantini said:
    Do you have any idea of ​​the possible causes? Is this an echo phenomenon?

    In addition to the above two points, this is also related to your pipe's structure.

    Please try to optimize pipeline structure, set a smaller ultrasonic emission time, also set a reasonable ultrasonic sampling time.

    Reagrds,

    Helic

  • 0 in reply to Helic Chi
    Prodigy 20 points

    Hi, Helic,

    Thanks for your reply.

    Sure, sampling time has to be set to a reasonable interval, closing window at the end of useful signal.

    I have set a large sampling window in order to observe the problem on entire signal: useful + echo.

    As shown in this image, echo signal merges with the end of useful signal, so useful signal never goes to zero. 

    I wonder this phenomenon represents a problem for the final sampling resolution, I think so..

    What do you think about?

    Smaller ultrasonic emission time doesn't resolve the issue:

    - number of pulses reduced from 30 to 10

    - UPS to DNS gap reduced from 3ms to 1ms

    Regards,

    Paolo

  • 0 in reply to Paolo Costantini
    TI__Mastermind 46765 points

    Hi,

    Use less excitation pulses could help to resolve the issue. In water meter application, we actually do not need that much pulses here. 

    Best regards,

    Cash Hao

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