Re: GPS trackers - a potential weapon from hell

Ken Taylor wrote:

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"Joseph2k" <joseph2k@xxxxxxxxxx> wrote in message
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Frithiof Andreas Jensen wrote:


"Paul Hovnanian P.E." <Paul@xxxxxxxxxxxxx> wrote in message
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Richard the Dreaded Libertarian wrote:

[snip]

Well, if cell phones can work from inside an airplane, then somebody
evidently has some pretty sophisticated RF technology in place.

Cell phones only have to see a single base station 5 to 10 miles away
on
the ground. GPS receivers have to see at least 3 (or is it 4)
satellites
simultaneously, orbiting at several hundred miles altitude.

Nothing so sophisticated, "they" place a mobile base station on the
plane
and bundle the traffic into another protocol that goes over sattelite.
(The mobile network will not like it very much when the planeload of
cellphones travels at 600 km/hour and each phone does a location update
every 200 msek when blazing past the base stations. I.O.W: it will not
work).

Getting the sattelite link to work is the hard bit - sattelites are
good for massive downlink capacity but the uplink suck.


Let's discuss up link vs down link: for TV, data, Telephone (mostly gone
now (GEO), but resurging at leo), etc. everything but sensor sat's, and
GPS
up link = down link, almost exactly (to be expected of "flying"
repeaters).

Uhuh. I suggest you do some research - plenty of phone on GEO,
comparitively little on LEO and not resurging or even surging. Uplink <>
downlink - you clearly don't know the subject.


If you are talking about Iriduim or its main competitor they are both leo.
expected you to know. lots of beepers are geo. If you are talking about
transoceanic or transcontinental telephone it is mostly on fiber. The
customers found the geo delay disturbing.

Cell phones do not work well in airplanes (mid flight) because normal
cell phone site antennas are oriented (and have emission patterns) for
surface traffic.
--
If a microcell is placed on a plane I would suggest that ground station
antenna patterns are irrelevant. There are some well-documented instances
of perfectly adequate calls taking place from aircraft, and FAA released
estimates only yesterday of an average of 3-4 calls per flight over the
US. I think it can be safely said that cell phones will work perfectly
well in an aircraft in flight.

I did not say they would not work, i was pointing out that the ground
station antenna paterns were not in favor of it.

JosephKK

Ken


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--
JosephKK
Gegen dummheit kampfen die Gotter Selbst, vergebens.
--Schiller
.

Relevant Pages

  • Re: GPS trackers - a potential weapon from hell
    ... Cell phones only have to see a single base station 5 to 10 miles away ... perfectly adequate calls taking place from aircraft, ... estimates only yesterday of an average of 3-4 calls per flight over the US. ...
    (sci.electronics.design)
  • Re: GPS trackers - a potential weapon from hell
    ... Cell phones only have to see a single base station 5 to 10 miles away on ... "they" place a mobile base station on the plane ... Cell phones do seem to work marginally. ... Much to the chagrin of the FAA and network operators, ...
    (sci.electronics.design)
  • Re: GPS trackers - a potential weapon from hell
    ... Cell phones only have to see a single base station 5 to 10 miles away on ... "they" place a mobile base station on the plane ... Getting the sattelite link to work is the hard bit - sattelites are good ... Cell phones do not work well in airplanes because normal cell ...
    (sci.electronics.design)
  • Re: GPS trackers - a potential weapon from hell
    ... Cell phones only have to see a single base station 5 to 10 miles away ... I suggest you do some research - plenty of phone on GEO, ... comparitively little on LEO and not resurging or even surging. ...
    (sci.electronics.design)
  • Re: Any wireless broadband providers about?
    ... TV antenna] would be the best way to eliminate collisions at the node ... connection, as you'd have to be directly between the base station and the ... As for a mobile wireless service, ...
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