[time-nuts] Thunderbolt SV and AMU Signal levels

[Mike S]

At 07:14 PM 7/22/2008, David Ackrill wrote...
>So, my guess is that my poor old counter is +/- 10Hz out, but that may 
>
>be due to the age and non-calibration of my frequency counter over the 
>
>years.
>
>Or... The Thunderbolt 10MHz output is moving up and down by 0.00001 
>MHz
>within a 10MHz band.

That would be extremely unlikely. Your counter timebase is changing, 
probably temperature related.

Oh, SV is "Space Vehicle," and is probably being used incorrectly - the 
Thunderbolt is likely reporting the PRN (Pseudo Random Noise) number 
for each of the signals received. For the first GPS satellites, SV 
typically equalled the PRN, but that is not required to be the case, 
and it isn't always. For example, in 1993, SV-32's PRN number was 
changed from PRN#32 to PRN#01, due to poor programming in some GPS 
receivers.

AMU are "amplitude measurement units," (aka "arbitrary mystery units") 
and are used to report S/N of received signals.