Re: ProgRock not working #progrock

Robin Midgett

Hi Sid,
If you read back through the email chain you'll find Hans' statement concerning 1Hz./µS latency; that's how I became informed of the factor. He did say variable latency which certainly would bring error with it. I'm of the opinion that I do not have variable latency, but rather fixed latency as shown in my most recent email with the 'scope display showing the 1PPS from my Trimble T & the 555 rising output. That latency is on the order of 750nS, and if it's steady in it's timing, shouldn't introduce any error.

My QLG1 arrived yesterday, so I hope to have more insight into the situation soon. I'm interested in seeing what is the cause of the error you're experiencing since, as I understand it, you already have a QLG1 GPS in the lash up.
Robin Midgett K4IDC

On Sun, Jul 21, 2019 at 9:58 AM w7qjq <sbjknox@...> wrote:

Regarding 'latency' is my understanding that the value of the latency of the 1PPS has no relevence to the CLK0 frequency accuracy. What is revalent is that the latency be a constant value and that the 1PPS pulse width be at least several mS (the QLG1, and many other GPS receivers' 1PPS is 100 mS),  and very importantly that the positive-going leading edge be very fast and clean.


73,  Sid  W7QJQ

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