GPS trackers - a potential weapon from hell

Actually, it is not that bad. The L1 and L2 signals are about the same level (in terms of bandwidth*power) vs current noise levels (for ordinary antennas [no larger than 100 mm on a side, smaller antennas may have lower performance]) (at 1.2 GHz and 1.5 GHz, 1/4 wave antennas are not very large, and seeing as you do not want directionality in the receive antenna, good narrow band LNA'a become very worthwhile). 10-bit chipping gives about 6 dB usable gain.

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

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).

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.

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

on

satellites

plane

GPS

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 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.

Ken

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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.

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

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

Who said Iridium *wasn't* LEO?? And what has 'beeper' traffic got to do with anything?

Traffic has moved from GEO to fibre where possible not because of the delays being 'disturbing' (I challenge you to tell the difference on a single-hop satellite voice call) but because of economics.

Just >>>>every 200 msek when blazing past the base stations. I.O.W: it will not >>>>work).

And your crap about link budgets still exposes your inadequate grasp on the topic.

Ken

IBM's internal voice network was GSO satellite back in the '80s. It was next to unusable with the 3/4 second round-trip delay. People had to train themselves to use it. It was almost to the point that people would say "over" when they were done with a phrase, then wait. Interestingly, if the content of the phone call was Confidential, we were supposed to use the ATT dial network since it was more "secure". Guess what percentage of the calls ended up being classified as Confidential. ;-)

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  Keith

Early analog systems had pretty poor echo-cancellation, which tended to exaggerate delays. Plus of course the GEO delay when added to any terrestrial delay can become a problem. But modern digital stuff sounds like next door, until you start double-hopping, which even then is still acceptable if the alternative is an envelope and a stamp. If terrestrial capacity is available though, it gets everyone's nod, as you note. :-)

Cheers.

Ken

It was a digital system (IBM isn't known for analogs), though pretty poor.

3/4 second is still enough to confuse the untrained (and no one wants to be "trained" how to speak). One PHB even demanded that the satellite be moved closer to eliminate the delay. The alternative proposed by the engineer (a friend) was to change C.

Available? It's always available, perhaps at a different cost. As long as it's not *my* cost...

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  Keith

Love it - did you get funding for the c change? Maybe a C programmer required.....

I had a very senior sales rep from a certain undersea fibre company travel many thousands of miles over several days to visit me and extort the value of his fibre-laying division, and how the cable would pay for itself so quickly. He was most embarrassed when I pointed out he'd dropped a zero in his calculations! Begged me not to tell anyone it had happened - it's a promise I kept.... mostly. :)

Cheers.

Ken