[hpsdr] FMT differences between Magister and Metis?

[Ron Mozer]

Very curious, using the PowerSDR v1.19.3.3 (W5WC 2/25/11) I did a little 
experiment using K1JT's FMT (Frequency Measuring Test) utility.   My 
setup includes an Excalibur feeding a 10 MHz reference to the Atlas buss 
from a Thunderbolt GPS with a short term error in the realm of 0.03 PPB.

By only changing the physical interface and matching it in the PowerSDR 
setup, I see about 0.35 Hz difference in the measured frequency between 
the USB interface on Magister and the IP interface on Metis when 
referencing WWV on 10MHz.

In fact Metis has a repeatable error of  about -0.35 Hz compared to a 
more respectable error of less than 0.007 Hz when using Magister.

If it makes a difference, I still have Metis V 1.0 installed and am 
running on a Windows 7 x64 platform.

Perhaps those playing with FMT can provide some insight as to tricks 
they do with the HPSDR to minimize error.  I was thinking of trying to 
use ghpsdr3 running multiple receivers.  Have a couple receivers locked 
to different WWV frequencies and one measuring the unknown frequency.  
This might allow one to zero out apparent frequency changes due to the 
Doppler effect.

73 de WY3D
Ron