1. gary1wang

    Thread Starter Member

    Sep 18, 2008
    23
    0
    Hi guys


    I programmed a microcontroller and it samples 200 times on a value of voltage, I want to reduce the noise affecting on the signal, so i sum samples and then divide by 200. But result is not very good, it still have some variation.


    Can you recommand a better way to do it


    Thanks

    Gary Wang
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    External RC filter.
     
  3. Mark_T

    Member

    Feb 7, 2012
    47
    8
    To answer this one correctly we need to know the nature of the signal being sampled. Is it DC with noise, and how much noise. But RC filter close to micro is the start and make sure Vref is clean to.
     
  4. Mark_T

    Member

    Feb 7, 2012
    47
    8
    Also, if its line noise 50Hz make sure you sample over many cycles. Put a delay between the samples.
     
  5. gary1wang

    Thread Starter Member

    Sep 18, 2008
    23
    0
    It output by DAC, and each step, It measures 200 times and I placed a simple RC filter at the ADC input. and also the RC low pass filter cutoff frequency is twice of ADC sampling rate
     
  6. MrChips

    Moderator

    Oct 2, 2009
    12,446
    3,362
    If it is line frequency noise, make sure that you sample over an exact integral number of complete cycles. For example, if it is 50Hz AC noise, sample for a complete cycle of 20ms duration or any multiple of 20ms.
     
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