On 4/7/19 6:48 AM, Fons Adriaensen wrote:
> On Sat, Apr 06, 2019 at 12:32:29PM -0400, Tim wrote:
>
>> So the software would be able to deal with sines better,
>> and measure phase differences rather than a pulse edge.
>
> Sure, the pulse will be 'smeared out' a bit, and its actual
> position may seem to be ambiguous. But that's no problem.
>
> What you get in the sample stream is the impulse response
> of the A/D converter. Assuming that this is a linear and
> time-invariant system, the IR contains all information.
>
> If the pulse is smeared out, one way to find the delay is
>
> 1. Compute the FFT of the part of the sample stream that
> contains the smeared-out pulse.
>
> 2. Compute the phase of each frequency bin. If the delay
> is independent of frequency (it should be if the A/D
> is any good), then the phase will be a linear function
> of frequency. The slope of that function indicates
> the delay (relative to the start of the FFT input).
>
> The only advantage of using sine waves is that your test
> signal has much higher energy than a single short pulse,
> so you get a better S/N ratio. But for this test, the
> S/N will be very good anyway.
>
>
> Ciao,
>
Awesome, thank you!
Tim.
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Received on Mon Apr 8 00:15:01 2019
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