I have seen some GPS Notams about likely unreliability in certain
areas over certain very narrowly-defined periods of time. Can anyone
tell me what sort of known activities create these conditions?


-Robert Scott
Ypsilanti, Michigan

Periodic uploads of ephemeris and clock data to the SV, testing,
maintenance, switching of clocks, etc. from Master Control at Schriever Air
Force Base.

J. Severyn KLVK

"Robert Scott" > wrote in message
...
>I have seen some GPS Notams about likely unreliability in certain
> areas over certain very narrowly-defined periods of time. Can anyone
> tell me what sort of known activities create these conditions?
>
>
> -Robert Scott
> Ypsilanti, Michigan

"J. Severyn" > wrote in
:

> Periodic uploads of ephemeris and clock data to the SV, testing,
> maintenance, switching of clocks, etc. from Master Control at
> Schriever Air Force Base.

And tests of jamming equipment. The only way to be sure whether a system
can be jammed is by jamming it.

--
Regards,

Stan

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety." B. Franklin

Robert,

tests and/or usage of ground-based jamming equipment.

As the people at Schriever AFB have explained to me, uploads of data
(each satellite has to be "touched" by the ground station at least once
per day - talk about maintenance intensive) do NOT disrupt service.
Also, it is not really possible to deny service to well defined
geographic areas by switching off satellites.

--
Thomas Borchert (EDDH)

J.,

> Periodic uploads of ephemeris and clock data to the SV, testing,
> maintenance, switching of clocks, etc. from Master Control at Schriever Air
> Force Base.
>

Hmm. What, if I may ask, is your source for that? The people at Schriever told
me specifically these kinds of things will not disrupt service.

--
Thomas Borchert (EDDH)

Get current status here:
http://www.navcen.uscg.gov/gps/gpsnotices/

"Thomas Borchert" > wrote in message
...
> J.,
>
>> Periodic uploads of ephemeris and clock data to the SV, testing,
>> maintenance, switching of clocks, etc. from Master Control at Schriever
>> Air
>> Force Base.
>>
>
> Hmm. What, if I may ask, is your source for that? The people at Schriever
> told
> me specifically these kinds of things will not disrupt service.
>
> --
> Thomas Borchert (EDDH)
>

That is a good question.

How can they tell a area will have a GPS problem for a short
amount of time??

If it is interference, it should be eliminated. Makes you
wonder about the stupid plan by the FAA to shut off VOR and
DME's around the country.

That would be very DUMB. I have also noticed more and more
VOR's, NDB's, ILS's and DME's broke and not in service
around the country on the NOTAM database. Scary.

Looks like the FAA can't keep their stuff running huh??


Robert Scott wrote:
> I have seen some GPS Notams about likely unreliability in certain
> areas over certain very narrowly-defined periods of time. Can anyone
> tell me what sort of known activities create these conditions?
>
>
> -Robert Scott
> Ypsilanti, Michigan

SolarSapien > wrote in news:nt9ke.11440$8S5.6401
@bignews3.bellsouth.net:

> Looks like the FAA can't keep their stuff running huh??

GPS does not belong to the FAA, and they don't run it.

--
Regards,

Stan

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety." B. Franklin

I was speaking of DME's, VOR's, ILS's, NDB's etc.

FAA does run the WAAS network however

Stan Gosnell wrote:
> SolarSapien > wrote in news:nt9ke.11440$8S5.6401
> @bignews3.bellsouth.net:
>
>
>>Looks like the FAA can't keep their stuff running huh??
>
>
> GPS does not belong to the FAA, and they don't run it.
>

Thomas Borchert wrote:
> Robert,
>
> tests and/or usage of ground-based jamming equipment.
>
> As the people at Schriever AFB have explained to me, uploads of data
> (each satellite has to be "touched" by the ground station at least
once
> per day - talk about maintenance intensive) do NOT disrupt service.
> Also, it is not really possible to deny service to well defined
> geographic areas by switching off satellites.
>
> --
> Thomas Borchert (EDDH)

I guess whether or not a disruption may occur would depend upon what
the definition of 'service' is. If it includes the 'availability of
integrity to conduct an approach' then:

There are cases where a satellite taken OTS, can affect availability of
integrity using standalone GPS (RAIM) as well as cases where
availability of integrity using WAAS is not guaranteed.

As 'GPS' is sometimes used as an umbrella term, it wasn't clear from
the original post whether the NOTAMs referred to, were GPS NOTAMs or
perhaps WAAS NOTAMs as the latter can contain the UNREL contraction.


Regards,
Jon