[time-nuts] Thunderbolt reception problems
Magnus Danielson
magnus at rubidium.dyndns.org
Sun Nov 22 23:39:58 UTC 2009
GandalfG8 at aol.com wrote:
>
> In a message dated 22/11/2009 21:23:49 GMT Standard Time, bg at lysator.liu.se
> writes:
>
> 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.
>
> 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.
>
>
> ----------------------
> Ah, that explains it, I wasn't aware there were two options but you're
> quite right.
>
> I don't recall switching it, and Thunderbolt Monitor doesn't seem to have
> the option to switch it anyway, but I found the option in GPSMon 1v05 and
> 1v6 and it can indeed be toggled.
The Thunderbolt Monitor does have it, I just ticked the box and had my
C/N measures instead. In the "Setup" menu, select "Packet Masks and
Options..." where you in the "Packer 35 Options" frame, the "Auxiliary
(Byte 3)" sub-frame find a tick-box for "Output dBc/Hz". Tick the
tick-box and press the "Set Options" button and you get dBc/Hz values
rather than AMU values.
> Whereas GPSMon changes the label of the field to suit it doesn't help that
> Thunderbolt Monitor leaves it described as AMU regardless of the setting:-)
A bit confusing indeed, but the values should never really overlap, so
values should be a good hint on what to expect.
Bottom line, use C/N values whenever you can.
Cheers,
Magnus
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