[time-nuts] Frequency counter questions

Magnus Danielson 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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