----- Original Message ----- From: "Peter L. Peres" To: Sent: Friday, September 14, 2001 7:06 AM Subject: [OT]:cell phone locating > > Some months ago there was a thread on jamming cell phones. Now I am > > wondering how to get the spatial coordinates of a given cell phone. > > Is it technically feasible to identify a single cell phone from a > > satellite or other high point? > > > > Maybe you can guess what I'm wondering. > > > > alice > > I have no idea why you are wondering but you can consider a digital GSM > phone as a 0.6W (at most) digital isotropical transmitter for most > purposes, and apply that to the radio link equation. You will end up with > a pretty big antenna to receive it at some distance (like 10 miles). Ten miles is actually a pretty easy path - unless you're trying to "work through dirt" or a lot of urban buildings. I regularly work these distances at UHF with a .5 Watt UHF radio ... > Normal cell tower antennas are approx. 1.2 x 0.4 meters in dimensions, > with a dielectric lens that also serves as radome. The lens gives wide > coverage (135 degrees or so usually). Most of those 'covers' are only 'covers' - within you will find a variety of either dipoles, patch antennas, etc coupled together with a phasing harnesses ... > > You can probably use one with a narrow lens mounted on an azimuth bearing > on the roof of a small truck or van to get a bearing, using a band imaging At these frequencies - and-held yagis are MOST suitable ... > receiver. By moving the truck and getting a second bearing you could get a > fix on a location. I guess it would take a 5 minute transmission and a I have chased down "un-cooperative" sources as a matter of tracking down RFI (Innterference) sources. With a little practice, you'd be surprised at what you can do ... > 300ft base to get a reasonable fix in urban conditions at close range. > > This would still not tell height or depth. Maybe the antenna could be > swiveled to get a vertical angle bearing to judge height or depth. > Basically it would have to be gymballed, maybe in a gymbal meant for a > large spotlight. > > I think that such antennas can be ordered ready made from cell equipment > makers. Figure up to $4000 or so for the antenna alone (it usually has > attached electronics), but I am sure they would donate one for a good Wha? Sounds like an integrated cell site or a remote duplexer/power amp combo. Most of these 'antennas' alone are 1/4 that price ... > purpose. > > I think that is is more interesting at the moment to locate a phone at > short distance (f.ex. in rubble). Also pagers/voice mail originators > (PDAs SMS etc). I have tracked down 'active antennas' that oscillate and sweep through the UHF amatuer band - models like the Radio Shack ATV-1000, a set-top model. One that was giving me trouble was just under a mile away ... these things radiate at low power - no where near the max. power output of .6 watts at power level 3 of a cell phone. Jim > > Peter > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads