[time-nuts] GPS interference and history...
wa1zms at att.net
Sat Jun 11 11:40:57 EDT 2011
you coming to greylock?
On Jun 11, 2011, at 12:13 AM, bownes <bownes at gmail.com> 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 <hmurray at megapathdsl.net> wrote:
>> lists at rtty.us 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
>> 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
>> 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
>> 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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