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TIDM-1019: ADC capture

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Replies: 7

Views: 287

Part Number: TIDM-1019

Hi,

1) Is this a good ADC capture at zero flow rate for following settings?

Transmit frequency :986 kHz

UPS0 to UPS1 gap :500 ms

Gain :6db

Capture duration : 50us

Envelope threshold :20

2) I noticed that I always have some waves in the ADC waveform capture that are "attenuated".Is there something I can do to make it look cleaner? 

Best Regards,

Divya Harikumar

  • Hi Divya,

    1. The capture itself looks good, but I'd recommend starting the ADC capture sooner to center the waveform more. Try decreasing the ADC gap start value by about 3us. 

    2. Can you clarify where exactly in your capture you see the attenuation?

    Thanks,

    Mitch

  • In reply to Mitch Ridgeway:

    Mitch,

    Well i have marked the points with attenuation.

    Best regards,

    Divya Harikumar

  • In reply to Divya Harikumar:

    Hi Divya,

    What you are seeing are artifacts of the sample rate you are using. This is normal and the capture itself looks good! If you wanted to clean up the signal, you can interpolate the data by exporting the capture data to a .csv file and importing it to Matlab. In Matlab, you can interpolate the signal.

    Thanks,

    Mitch

  • In reply to Mitch Ridgeway:

    Hi Mitch,

    I have a couple of questions 

    1)Which is a better ADC capture (A) or (B) and why?

    2) It was suggested that i should reduce the ADC gap start  .Is there any other importance of reducing gap between pulse start and ADC capture?

    Regards,

    Divya Harikumar

  • In reply to Divya Harikumar:

    Hey Divya,

    1. Your waveform is more centered in A, so I would say this capture is "better". Besides your ADC gap start parameter, are there any other parameters that are different between the two captures?

    2. Reducing the gap between pulse start and ADC capture will center your capture more. This is important because as temperature varies, you will notice your capture will shift left or right, depending on if temperature increases or decreases. Centering your captures initially will help alleviate this effect.

    Thanks,

    Mitch

  • In reply to Mitch Ridgeway:

    Hey Mitch,

    There are a few parameter changes besides ADC gap start.

    For, Waveform A: Capture duration = 60us , no:of pulses=30 and ADC gap start = 57us whereas

           Waveform B: Capture duration = 50us , no:of pulses=25 and ADC gap start = 60us

    Is waveform A still a better choice of ADC waveform?

    Best Regards,

    Divya Harikumar

  • In reply to Divya Harikumar:

    Hey Divya,

    Both waveforms are acceptable, but you might want to consider reducing the start gap for waveform B to 57us as well. This, along with the lower number of pulses, will give you a more centered reading along with lower power consumption. A more centered waveform will give you a more stable reading over a wider range of flow rates - as the waveform may shift as flow rate changes.

    Thanks,

    Mitch

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