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

[Erik Kaashoek]

Tyler,
You did not mention what accuracy is needed.
With a PPS from a modern cheap GPS receiver with a good GPS signal you can
expect a 1 s ADEV of 1e-8
Direct usage of this PPS to directly gate and count 100MHz will give you a
bit worse performance for your counter, say 3e-8, or average error of 3 Hz
per second gate time when measuring the 100MHz
With a not so good GPS signal this average error may increase to 30 Hz.
Erik.


Op za 24 jun 2023 om 03:35 schreef Tyler H via time-nuts <
time-nuts at lists.febo.com>:

> 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
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe send an email to time-nuts-leave at lists.febo.com
>