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ADS1281: Is ADS1281 fittable for a signal with 0.1Hz ~2Hz?

user3677382
Prodigy 200 points
Part Number: ADS1281

HI TIer,

      I would like to samle a signal with 0.1Hz~2Hz bandwith. At first I thought ADS1281/2 is the one I need. However, th Figure 21 in ADS1281 datasheet confused me. Does it mean ADS1281 is not a good one for this case?

  • 0
    TI__Mastermind 44550 points

    Hi user3677382,

    Excellent question! Yes, the ADS1281/2 is suitable for 0.1 to 2 Hz signals...

    Unfortunately, Figure 21 shows what happens when you forget to subtract the DC offset from the FFT before applying a Window. A 20mV DC offset voltage was applied to the inputs and then the data was windowed by a 7-term Blackman-Harris window function. The signal amplitude of -40 dBFS results from the ratio of the input voltage to full-scale range:  20*log10(20mV / 2.5V), and the spectral leakage across 7 FFT bins (i.e. 7 Hz, since each FFT bin is 1 Hz wide in Figure 21) results from the wide main lobe of the window function. 

    Image result for 7 term blackman harris window

    I hope that helps!

  • 0 in reply to Christopher Hall
    Prodigy 200 points

    Got it with thanks!