[time-nuts] GPS interference and history...

bownes bownes at gmail.com
Sat Jun 11 00:13:00 EDT 2011


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 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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