[time-nuts] Frequency counter questions
magnus at rubidium.dyndns.org
Wed Apr 26 03:45:32 EDT 2017
On 04/26/2017 06:29 AM, Jerry Hancock wrote:
> Do typical frequency counters start their gate in phase with the incoming signal? I guess the
> answer would be, "It depends." I was just thinking about how I would program the STM32F7
> counter I am designing.
No. The start of the gate arms the "start" event where you time-stamp
the start event. The end of the gate arms the "stop" event. Variation
can be that you start counting the gate time and arm it with a start
event. Typically the internal gate time is counted in the coarse clock,
so the time-resolution as given by interpolators always guarantee that
the wished gate-time and actual gate time is never really the same.
Rather, gate time is a guidance value but you then measure the actual
length, and neither start or stop is on the same edge.
> btw, Gilbert, a local time-nut, sold me a 5335 today so I will be able to buiild one great one
> out of the two I will have.
Not a bad first counter. It still does some tricks that none of my other
counters do, and I kind of have a bunch of them by now.
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