Re: ProgRock OCXO and GPS locked frequency accuracy.

Phil Crockford

I have done investigation on the accuracy of the GPS control using the Synth module in both the PRO-ROCK and the VFO Sig-gen and I also confirm a frequency difference between an off air standard and the GPS locked frequency derived by the two products.

If a synth module is used in the PRO-Rock it produces a frequency which deviates from the programed frequency by around 2 Hz and does not seem to attempt to correct any further in order to align with the off air standard. However if the same synth module is used in the VFO SIG-Gen and corrected by the same GPS used for the PRO-Rock the Sig-Gen produces an accuracy of better than .5Hz from the programmed frequency and continues to correct itself from then on.

Until now I have resolved to apply a correction to the programmed frequency when using in the Pro-Rock and was content not to communicate my findings to the group. I have a number of Synth modules , OCXO and standard and find the same with all modules when compared in this manner.

The initial acquisition process in the Pro-Rock seems to work well but once this is achieved it seems reluctant to control the frequency any further.

This test have been done with the correction set to 001 and also set to 000 but the pro-rock seems to fail to control the frequency to within less than 2Hz.

Both the Sig-Gen and the Pro-Rock have been run at the same time and controlled by the same GPS using two Synth modules known to exhibit the 2Hz error. The Sig-Gen produces a frequency that is correct to within less than .5Hz but he Pro-Rock Controls to within 2Hz.


This email is by way of information and is not intended a criticism of any  product.





From: [] On Behalf Of Mark Horn
Sent: 09 May 2020 19:26
Subject: Re: [QRPLabs] ProgRock OCXO and GPS locked frequency accuracy.



Forget my last message after three hours of being within 0.5ppm I went for dinner and when I came back it was off by 1.5Hz again.  :-(  I'll leave it run for another hour and see what it measures then.

73 Mark

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