[time-nuts] Missing GPS satellites

[Steve Rooke]

I'm at 43S, 172E and the minimum number of birds I'm seeing in the
middle of the days is 4 with a maximum of 12 each night. No sign of a
let up here, guano all over the place :)

Steve Rooke

On 26/03/2010, Raj <vu2zap at gmail.com> wrote:
> Rob, I am 13N 77E approx.
>
> Bob, I checked everytime and no birds. I setup two GPSDOs with seperate
> antennas and both went to hold over.
>
> Its been happening ever day at some times. Even I get the error on this page
> http://www.n2yo.com/whats-up/?c=20
>
> Lady heather says the doppler is high or something and satellites not
> usable. Sometimes there are 3 sats overhead and none usable!
>
> At 26-03-10, you wrote:
>>What's your latitude Raj?
>>
>>Rob K
>>
>>-----Original Message-----
>>From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>>Behalf Of Bob Camp
>>Sent: 25 March 2010 11:15 PM
>>To: Discussion of precise time and frequency measurement
>>Subject: Re: [time-nuts] Missing GPS satellites
>>
>>Hi
>>
>>I still think it's a bird on the antenna.
>>
>>Bob
>>
>>On Mar 25, 2010, at 7:11 PM, Magnus Danielson wrote:
>>
>>> J. Forster wrote:
>>>> From an unnamed, but VERY credible source:
>>>>
>>>> "> It might be that the DoD is turning the civilian signals off in
>>>> combat
>>>>
>>>>> areas to deny GPS to the Taliban and others.
>>>>>
>>>>
>>>> Quite possible.  This countermeasure was discussed more than ten years
>>>> ago.
>>>>
>>>> It is possible to turn of the civilian signals -- or to leave then on
>>>> but _jam_ them within a selected area -- without interfering with US
>>>> military use of the satellites.  A modern military does not need the C/
>>>> A code to acquire lock on a satellite.  It can acquire the encrypted P
>>>> code directly."
>>> The preferred method of controlling the access to GPS within a region is
>>> GPS jammers, and the full set of efforts being spent on strengthening
>>> the allied forces availability to signal is to ensure ability to survive
>>> from jamming signal, which includes removing need for C/A locking prior
>>> to Y-code lock with direct lock methods, transfer of time, solutions and
>>> ephemeris data, and eventually means to direct additional power towards
>>> the area and the improved M-code.
>>>
>>> Turning of the C/A code of a satellite will effect the 1/3 of the earth
>>> area that it sees, and for that to be effective in a certain area, you
>>> need to do that to 6-8 sats to turn it off, and that will significantly
>>> reduce the GPS availability for so large geographical areas that things
>>> they want to work will run closer to failure. So no, turning of C/A code
>>> is not what they want to do it. They can, but they want to avoid it.
>>>
>>> Cheers,
>>> Magnus
>>>
>>>
>
> --
> Raj, VU2ZAP
> Bangalore, India.
>
>
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-- 
Steve Rooke - ZL3TUV & G8KVD
A man with one clock knows what time it is;
A man with two clocks is never quite sure.