Hi,
Juergen Specht wrote:
>Too much "I worked" and "I doubt" in your reply...how old is
>your information? The technology involved does not work
>by simply put some cells somewhere, you need to know the
>environment very well...simply spoken:
>
Okay.. can you point me to some resources so that I can better understand
what you are talking about then?
>Look ahead technology. Compare streetmaps, house locations,
>most used places by phone carriers (people), user behaviour, weak net
>access points, magnetic field of the earth, run time lengths and more
>parameter in a powerful computer, mix it, blend it, shake it and
>calculate the exact location (also the height of a phone in buildings)
>of a mobile phone.
>
I`m very interested to see the algorithm that goes into calculating this and
the sources of all these parameters that you just mentioned.
The RF signal strength information from 3 or more cells (like in the diagram
you drew in the previous email) along with the Time Alignment factor is used
to pinpoint the location of mobile users. However, when mobile user is
moving, RF signal strength received by your mobile phone may various up to
10-20 dB because of what`s called "signal fading effect" caused by various
signal that comes from various paths to your phone (multipath). In the end,
this method is a very unreliable way to calculate the user position.
This is with no GPS involved. Of course, nowsaday you can do send GPS
information via cell network. That will give you a much more accurate
position info.
>Funny side effect: this works great with moving objects, but not
>with fixed objects. With fixed objects you lose focus over time
>(read microseconds) and than you are right...15 meter is the
>average.
>
>Be sure that this system is not invented nor used by a Telco
>and specially not for the announced location system, it's still
>too expensive. And who has so much money to invent a system like
>this? Right.
>
Would you mind tell us who use the system then?
Thank you very much,
Punnamas
>J.
>
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Received on Tue Aug 22 07:05:37 2000