[time-nuts] Zero-Crossing Detector Design?

[Magnus Danielson]

On 07/21/2012 12:09 AM, Azelio Boriani wrote:
> OK, very interesting. Now is it possible to measure/verify this? I think
> that using any test equipment, the comparator-style approach is
> unavoidable: the trigger of the scope or the counter cannot be an
> amplifier/limiter.

If you like to verify what I described, a scope is a good 
starting-point. Using a sine of say 10 MHz and then adding a sine of say 
1 kHz, you can fool around with trigger point, noise-signal level and 
source level and essentially learn it. Try trigger at zero-crossing, try 
trigger near the peaks. Vary the modulation signal amplitude.

> How to tell what is up to my design under test and what
> is the trigger contribution? Maybe only by comparison: test design A then
> design B and see which is better...

Varying the amplitudes is one thing. It's a good stress test. I assume 
you have means to measure it. Doing what I proposed above is also a good 
stress-test, add a noise signal and see how much you must have for it to 
cause serious harm.

I got myself a TimePod for a reason. I also use a CSA-803A scope when I 
need to.

Cheers,
Magnus