[time-nuts] Thunderbolt reception problems
Magnus Danielson
magnus at rubidium.dyndns.org
Sun Nov 22 15:05:26 UTC 2009
bg at lysator.liu.se wrote:
> Hi Said,
>
> With your background, I assumed you would know better...
>
> What is your antenna gain? What is your antenna cable loss? Does the Tbolt
> work correctly connected directly to the GPS antenna? Do you have an
> inline LNA to add close to the antenna? Do you have a higher gain antenna
> available?
>
> If 10dB is a lot or nost... that DO depend on the circumstances.
If you already moved the signal towards the lower end of the input
sensitivity range, then adding additional loss is an issue. GPS
receivers degrade their performance gracefully with lower input signal
to the point where it degrades more and more ungracefully. It's one of
the tests that one should do.
I have come to realize that my rig suffers severly from cable-loss and
the lack of antenna gain to be followed by a passive splitter before it
hits an active splitter. I had to build a gain-rig to overcome part of
that, but it doesn't feel right to use two LNAs in series. It's just
darkness before my eyes but it works.
The first fix to this is an inline amplifier to be inserted at the
antenna. Another fix would be to use a better antenna cable.
Cheers,
Magnus
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