[time-nuts] Thunderbolt reception problems

[Magnus Danielson]

bg at lysator.liu.se wrote:
> Hi Nigel,
> 
> AMU and SNR are two different scales. I do not have a translation. A
> Kepler award recepient once explained Trimbles AMU as "a meaningless
> unit". That said, SNR or C/N0 values cannot be directly compared between
> different receivers since the measures might be taken at different points
> in the receiver.

AMU is just a scaled linear correlation measure. Either this is Ip or 
the vector sum of Ip and Qp. Ip would suffice onces locked in. C/N 
measure is a combination of that and that of the pre-correlator noise. 
Wither this has been done or not is unknown.

> The Trimble monitor program can be made to switch between AMU and SNR in
> one of the configuration menues. I think you might have switched to SNR.
> 
> With above uncertanty of specific SNR definitions noted, most receivers
> are enjoying an excellent signal if the highest elevation receivers have a
> SNR above 50. If the highest SVs get +45dB that is still decent.

This is where C/N excel over AMU, it's easier to compare to other receivers.

Cheers,
Magnus