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ADC4229 test with tsw1400

tao chang1
Prodigy 110 points

When i test ADC4229 with tsw1400 , I have set the "adc sample rate" and the" analysis window "in the GUI ,i want to konw when should i select the "auto caculation of coherent frequencies"?

I only have a 20MHZ (maximum frequency）signal generator , i can't avoids an artifact of the FFT calculation from presenting a smeared power spectrum (when i give a Single-frequency Analog input )

  • 0
    TI__Genius 12965 points

    Hi Tao Chang,

    The Coherent Frequency selection is only used to help calculate the coherent frequency based on the number of samples in the FFT Analysis and the sample rate.  It is more of a calculator to help you find the closest coherent frequency to the one that is entered.  For example if you select the Coherent Frequency check box, then if you enter 10M it will give you the closest frequency you should use at the ADC input for it to be coherent with respect to the sample rate and the number of FFT samples.

    If you do not have a way to enter the coherent frequency in your signal generator then this check box does not need to be used.  You will have to apply a window to your samples to avoid spectral smearing/leakage issues in the FFT analysis.

    Ken.