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over sampling

Discussion in 'Microcontrollers, Programming and IoT' started by dcac, Mar 16, 2016.

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  1. dcac

    dcac

    56
    1
    Jul 10, 2013
    Hi there!

    I have a project where I need to analyse the code. The guy uses feature oversampling. The problems is that the guy uses oversampling on DC to get extra bits of accuracy. I have tried to look on the Internet but all I have found was different sources saying it can and others saying cannot be. I am quite confused. What is the truth? Can it be or not? If yes, how would determine oversampling frequency for ADC?

    Cheers!
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    11,702
    2,717
    Nov 17, 2011
    It can.

    Any ADC generated quantization noise. By oversampling and consequent decimation to a lower output frequency you effectively spread the noise from the A/D conversion over a much wider band of frequencies. Since decimation and downsampling reduce the spectrum contained in the output signal, the noise at higher frequencies is greatly reduced. As the noise power of the original spectrum doesn't change, the removal of noise at highe rfrequencies is equivalent toa a redcution of noise at lower frequencies which in turn is equivalent to an increase in resolution.

    The drawback is that the ADC's sampling frequency has to be much higher than the required output sampling frequency. A factor of 10 or more is not uncommon.
    On the other hand, this high sampling frequency on the input relaxes requirements on the analog anti-aliasing filter on teh ADC's front end.

    Wen you look at modern high resolution ADCS (20 bit and more), they mostly are Sigma/Delta types, the prnciple of which is based on oversampling.
     
    hevans1944 likes this.
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