bob-
you coming to greylock?
-Brian, WA1ZMS
On Jun 11, 2011, at 12:13 AM, bownes <[email protected]> wrote:
That small hemispherical antenna could also have been 900mhz. I have
one here @ home that is a combined gps/900mhz antenna from an
ambulance tracking system.
On Jun 10, 2011, at 22:01, Hal Murray <[email protected]> wrote:
[email protected] said:
There's an enormous amount of gear out there that gets timing off
of GPS.
That's an interesting claim. Does anybody have any data on the
usage of GPS
for timing?
I assume there is one in every cell tower and one in every 911 call
center.
Are there other large categories of users?
What would it cost to replace all of it? If you wanted to do
something like
that, what would "it" cover? How about people like us running old
recycled
gear? (Z3801A, ThunderBolt, ...)
I think I saw one last week. It was on a river level measuring
station on
the Sacramento River. It was a small block building. There was an
antenna
pointing up into the sky. I assume there is a satellite up there.
There was
also a small (~3 inch dia) hemisphere antenna. I assume it was
GPS. (They
had power going into the building (no solar panels) so it should
have been
simple to get a phone line too.)
I'm not sure why they need GPS at the recording house. They know
where it is
so timing is the only use I can think of. But they could also get
that at
the receiving end. Millisecond accuracy isn't helpful. Second level
accuracy might be interesting if something breaks and you want to
know when
the wave got to downstream stations. The risetime is probably over
a second.
--
These are my opinions, not necessarily my employer's. I hate spam.
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