[time-nuts] Re: building a frequency counter.. use 1PPS, ,or 10 MHz reference from GPS?

[Bob Camp]

Hi

The raw 1 pps pulse out of the typical module will have a sawtooth error on it. 
How big that error is depends on the module. It could / should / might contribute
several ppb of error when used as a 1 second gate. 

Bob

> On Jun 23, 2023, at 2:58 PM, Tyler H via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Hello!  
> 
> 
> 
> I'm building a frequency counter for some amateur radio microwave
> transverters to measure the local oscillators.  
> 
> 
> 
> I am designing towards a capability of directly counting up to 100 MHz and
> up to 200 MHz with a prescaler.  
> 
> 
> 
> For a time base, I'd like to use a 1PPS pulse from a GPS, but how accurate
> are they?   Should I just count a 10 MHz GPS reference and use that to
> generate a gate for the counter? 
> 
> 
> 
> Yes, there will be propagation delays in dedicated logic gates, but they
> don't appear to be too bad.  I should be able to get down to 100 Hz or so,
> which will be fine for what I need to do. 
> 
> 
> 
> I'd rather stick with dedicated counters and gates than move to an FPGA.  
> 
> 
> 
> Thoughts? 
> 
> 
> 
> Thanks!
> 
> 
> 
> Tyler
> 
> KM3G
> 
> Shrewsbury, PA
> 
> 
> 
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