anti-aliasing



Suppose one (actually, me) were firing an adc at some fixed rate,
ballpark 12 KHz in this case, and the input to the adc was a sine wave
of fixed but unknown frequency. The adc will take a bunch of samples,
ballpark 1000 maybe, and I want to compute the mean (ie, dc value) and
the mean of the abs value of the samples (ie, the ac value). That
works, but sometimes the input frequency aliases against the sample
rate and messes up the data, like gives a big average dc value when
there's really none there.

(This is not a Nyquist issue; the sample rate may be above or below
the sinewave frequency.)

So maybe I can fuzz up the sample rate so that it can't alias against
any constant sinewave frequency.

I could add a pseudo-random delay after every adc sample shot; but the
mean sample rate wouldn't change a lot. Or I could add successive
delays, essentially sweeping the sample rate down.

Any ideas?

John

.

Relevant Pages

  • Re: anti-aliasing
    ... Suppose one were firing an adc at some fixed rate, ... ballpark 12 KHz in this case, and the input to the adc was a sine wave ... So maybe I can fuzz up the sample rate so that it can't alias against ...
    (sci.electronics.design)
  • Re: anti-aliasing
    ... ballpark 12 KHz in this case, and the input to the adc was a sine wave ... The adc will take a bunch of samples, ... So maybe I can fuzz up the sample rate so that it can't alias against ... "Applied Control Theory for Embedded Systems" gives you just what it says. ...
    (sci.electronics.design)
  • Re: anti-aliasing
    ... ballpark 12 KHz in this case, and the input to the adc was a sine wave ... The adc will take a bunch of samples, ... So maybe I can fuzz up the sample rate so that it can't alias against ... I could add a pseudo-random delay after every adc sample shot; ...
    (sci.electronics.design)
  • Re: anti-aliasing
    ... ballpark 12 KHz in this case, and the input to the adc was a sine wave ... The adc will take a bunch of samples, ... So maybe I can fuzz up the sample rate so that it can't alias against ...
    (sci.electronics.design)
  • Re: anti-aliasing
    ... ballpark 12 KHz in this case, and the input to the adc was a sine wave ... The adc will take a bunch of samples, ... So maybe I can fuzz up the sample rate so that it can't alias against ... The success rate will be a function of something called the density of useful solutions... ...
    (sci.electronics.design)