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AWR1843: ADC sampling rate impact on signal and noise

Andy Yin
Genius 9320 points
Part Number: AWR1843

Hi Champion,

My customer reduce the sampling rate, increase the Tchirp, both signal and noise reduce, noise reduce more which would get stronger SNR. The question is why reducing ADC sampling rate would cause noise reduce, will noise reduce more if reduce ADC sampling rate more?

Suggest customer change HPF for try, increase the HPF, found the noise would firstly increase, then reduce. 

Would u pls help comment on above two test reports to help understand?

Look forward to your reply.

Andy

  • 0
    TI__Mastermind 20605 points

    Hi Andy,

    Can the customer share plots of the sampling rate to SNR noise in dB that they observed by changing the sampling rate? I can have the same looked at once internally and see if it is within expected boundaries. 

    Can you also confirm if the customer is using the AWR1843 EVM?

    Typically, the maximum variation in the noise would be around 1 dB across sampling rates.

    Regards,

    Kaushik

  • 0 in reply to Kaushik Gowda
    TI__Mastermind 20605 points

    Hi Andy,

    Thank you for sharing your plots. Here is some general information regarding the impact on signal and noise power based on an internal discussion:

    1. Signal Strength:
      1. ADC Sampling rate: Does not impact the signal strength.
      2. HPF: It can impact the signal strength only if the IF Signal frequency is less than 2* HPF Cutoff frequency.
    2. Noise power:
      1. ADC Sampling rate: This will directly impact the noise power with the following relation.
        Noise Power= (Noise Power spectral density * IF BW of ADC signal)
      2. HPF: The impact of HPF cutoff shifting on the noise is supposed to be negligible.

    Let us please continue the discussion over email.

    Regards,

    Kaushik