Some more recent phones have the possibility to be connected to seperate
GSM-boxes. E.g. there is a plug-in for the (older) Nokia 9210(i)/9290(i)
Communicators and most of the Symbian phones with Bluetooth support can be
connected to any Bluetooth-enabled GPS-mouse ...
I think, getting the position data with a defined accuracy is not the
problem. I'm quite satisfied with the location delivered by the CB channels
of the base stations. Crucial is indeed, what kind of location based
service you want to build and how the data gets to the server ... With
flatrate contracts regarding SMS or GPRS-data it's not even a real question
of costs anymore ...
But we slowly are getting completely OT for ASTERISK ;-) ...
For more info about "context awareness" and "location based services"
probably take some time to read what some colleagues here are doing in
research http://www.ist-mobilife.org/
-Jürgen
> Its my understanding the cell phone coordinates are sent to the cell phone
> provider and their equipment reads (and holds) that data. Its not part
> of any data available to you in any form unless you talk to the cell
> provider and convience them you have a valid need. Highly unlikely in
> the US anyway. Even if you could convience them to provide it, they
> would likely demaand some sort of out-of-band data transmission facility.
GSM networks have the Cell ID available to the phone, however that's not
much use without the location of the cellsite.
There are now location based services, whereby you can query the network
and they'll give out an approximate location (most cells are sectored
[6 sectors per cell) which gives a direction, the cell also knows what
power the phone is transmitting with, and the power it's received so can
make a good approximation of where the phone is (within 60 degrees
angle). However it's likely a phone will be picked up by several cells,
so the network can triangulate and make a better aproximation.
Making the information available to end-users is problematic due to
privacy issues, unless the user explicitly agrees to give the info away.
With GPS units, the info is stored in the phone and can send it out
using SMS or other means.
-------------
It was my impression that only a handful of cellphones have full GPS units
in them. Benefon and some Motorola units made for the former Nextel come
to mind. The Benefon units do send SMS reports, and in fact, I have
written code to control and track these units via SMS using a Nokia 31 GSM
terminal. Unfortunately, aside from their unique GPS/SMS capability, the
Benefons are not very attractive products, in my opinion. And they are
expensive. The Motorola units contain Java machines and a well defined
API for accessing the location data. I have not worked with them. There
have undoubtedly been changes in the marketplace since I did this work
about 2 years ago.
As I understand it (but don't have thorough knowledge and could be
mistaken), other units generally only receive GPS satellite signals and
relay the data to cellular provider networks where the actual location
calculation is done. This can be done with assistance of data obtained
based on tower proximity, which jumpstarts the iterative process of
approximation. I think it is called assisted GPS or some such...
_______________________________________________
--Bandwidth and Colocation provided by Easynews.com --
Asterisk-Users mailing list
To UNSUBSCRIBE or update options visit:
http://lists.digium.com/mailman/listinfo/asterisk-users
_______________________________________________
--Bandwidth and Colocation provided by Easynews.com --
Asterisk-Users mailing list
To UNSUBSCRIBE or update options visit:
http://lists.digium.com/mailman/listinfo/asterisk-users
