DSO vs Spectrum analysers for 100 MHz

Discussion in 'Analog & Mixed-Signal Design' started by yesilovethis, Sep 5, 2016.

  1. yesilovethis

    Thread Starter New Member

    Jul 28, 2016
    23
    2
    Hi everyone,
    I am planning to buy a DSO (Siglent 1000X most likely). I am curious how good is the FFT function of these scopes? are they able to show the harmonics and their relative powers (not accurate but approximate) of a RF device whose frequencies (e.g. 144 MHz) are higher than the Analog bandwidth of the scope itself (e.g. -3db bandwidth of 50 or 100 MHz)?
    How good is the resolution power and relative power measurement capability of these scopes in the lower RF band (< 30 MHz) for a DSO with 100Mhz analog bandwidth?
    Many thanks in advance.
     
  2. SLK001

    Well-Known Member

    Nov 29, 2011
    819
    228
    A FFT is only as good as the sample. I would say that you will not see anything useful beyond twice the sampling frequency. The analog BW has little to do with the digital capabilities of the scope.
     
    yesilovethis likes this.
  3. yesilovethis

    Thread Starter New Member

    Jul 28, 2016
    23
    2
    So a dso with 2GHz sampling rate has better fft resolution than a scope with 1GHz sampling rate? Thanks for information.
     
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