Chris Hastie wrote:
Perhaps drifting a little OT, but I suspect there will be people here
who have a lot more idea than I do about this.
I'm toying with the idea of getting a Garmin GPS18 LVC. The problem I
have is that all the places I can reasonably put machines to connect
it to are on the north side of the building, which is at a latitude of
52.275036 N. This gives me a rather limited view of bits of the sky
that GPS satellites actually turn up in.
So what I want to know is how easy is it to extend the cable of these
units, and what are the implications? I'd probably need an extra 8 -
10m to mount the unit on the south facing side of the building.
Presumably this will
1) Introduce losses. Will the signal still be useably strong?
2) Introduce delays. What sort of level of delay is involved, and is
it significant compared to, say, those introduced by the OS
(FreeBSD)
Thanks for any help
Chris,
The cable carries just 5V power and RS-232 signals, so extending 8 - 10m
should be no problem. There is no RF signal on the cable itself. Use a
screened multi-core cable.
At 5ns/m (about, for cable allowing for the velocity factor), the extra
delay (say, 50ns) is completely negligible compared to the accuracy of the
unit (~1 microsecond).
Cheers,
David
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