Re: MI automatically locating a caller on cellular networks

[John Brosowsky]

Rajeev,   The two main ways of doing this are TDOA which is time difference of arrival, and AOA which is angle of arrival.  TDOA uses the difference in time for radio signals from a cell phone to get to at least 3 cell towers to compute the coordinate.  AOA uses the angle that the radio signal from a cell phone hits equipment on two or more cell towers to compute the fix.  There are also hybrid methods that combine the two.  Search TDOA or AOA on the net and you'll get lots of info.  My company, GeoComm Corp, of St. Cloud MN, implemented a system for the national APCO conference last summer that located cell calls this way.  We took this a step further and used the located cell call coordinate to route the call through 911 telephone trunks that we actually terminated in a booth on the conference floor! We did this to prove to all how possible mad viable the technology is.  To accomplish this we acted as a consortium of companies: GeoComm (integrated mapping and communications), IES (Independent Emergency Services),DataMaster (911 data base software), CML Technologies (911 PSAP gear and digital telephone switch equipment), and KSI (the cellular location derivation gurus).  Check out more on this at www.geo-comm.com.   John Brosowsky         Hi mappers: This quewtion is not related much to MI but more tp cellular telephony. Is it possible to identify the location of a cellular celluar ( within say 20 to 25 metre accuracy) without the caller having having a GPS or similar device. Or oes the cellular switching has any information using which we can track a caller? Any pointers would be appreciated. I wam sure people in RF planning may have some answer to it. -- rajeev saraf