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

WA1ZMS wa1zms at att.net
Sat Jun 11 11:40:57 EDT 2011


bob-

you coming to greylock?


-Brian, WA1ZMS

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  
>> 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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