Triangulation, How to locate a cellphone? Options

[Homme-qui-rigole]

I know you can locate a cellphone with the triangulate program, but does there be other manner to localize a cellphone?

[Dende]

According to SR3 yes. All calls and everything go through the matrix, any decker can do a lacate test to find which phone, who it is registered to, etc...
Tracking is much easier for one who goes into the Matrix.

[Kurukami]

I'm not sure that would let you locate the current location of the cellphone, though. For that, you'd need to interact with the various comm towers that work with the cell phone network. As long as a phone was on, in theory it could be tracked in such a means.

But a simple location of a commcode would only tell you the basics -- for example, with a given commcode just who it's registered to, and so forth. Actually finding the current real-world location of said number would require the Triangulate utility.

[BitBasher]

you would be able to get a general area, down to a few miles automatically just by knowing what tower it connected to.

[mfb]

the Traceroute otaku echo would do it.

[Game2BHappy]

I could be wrong, but I believe Homme-qui-rigole is looking for a non-matrix solution for tracking down a cellular phone's signal. Unfortunately, I don't know of a canon solution for that.

This is not canon, but I think the cellphones are transmitting on overlapping frequencies and using encoding to keep one call differentiated from another. I would think that this would make tracking via a Signal Locator very difficult in the vast majority of areas ... unless your targeted cellphone was in the middle of the boonies and there were only a few cellphone signals in the area to track down and check out.

[mfb]

indeed. you'd be looking for a needle in a needle-stack.

[Kurukami]

True. Even these days (and back into the 80's, as far as I'm aware), you need to go through the phone company (often with a warrant) to do a legitimate trace on a particular call. With everything being handled by Matrix in the SR3 world, it seems likely that Matrix-work would be the only way to track down an active cell phone.

Short of getting Lone Star to work for you, natch. ;)

Recommended reading: "The Cuckoo's Egg", by Cliff Stoll.

[mfb]

if you know exactly what phone model and number you're looking for, it should be possible to determine the direction and strength of the cellphone signal. there's no gear in the game that will allow you to do this, though. i'm pretty sure such gear exists in real life.

[RedmondLarry]

You need portable radio receiving equipment that can listen to cell phone radio signals and differentiate one signal from another. Such equipment is commonly sold to go on cell phone towers, but receive-only versions exist that are portable. You need to be able to configure this system to report the signal strength of transmissions from a specific cell phone (by cell phone ID).

You need a directional antenna. The most common directional antennas give the biggest signal strength when it is pointed directly at a given transmission source, or directly away (180 degrees) from the source.

You need to get close enough to the transmitting cell phone for your antenna to pick up the signal, and have to determine the Cell Phone ID.

You need a map on which to draw lines. Stop somewhere close enough to pick up the signal. Rotate the antenna till you get the strongest strength. Draw a line on the map in the direction the antenna points (and in the opposite direction).

Drive somewhere else not on the line you've already drawn and repeat the procedure. You now have two lines on the map which should intersect. Drawing the lines from your two positions and determining the intersection is called Triangulation. This process can be distorted by reflections of signals off of steel-frame buildings, water towers, etc. Due to these distortions you may need to repeat the triangulation process several times, getting closer and closer to the stationary cell phone. Continue this process until you can identify which house or vehicle the signal is coming from.

This does not work if the cell phone is moving, because in the time it takes for you to reposition yourself the cell phone has moved off of the original line you drew on the map. For this you need two vehicles in different places, both with directional antennas and listening gear. You both determine the direction of strongest signal at the same time, and plot the intersection. By the time you get there, the target may have moved. Drive closer and repeat with the two receiving systems separated by some distance.

Alternate methods possible for the cell phone system itself is to have the three closest towers around the cell phone compare either signal strength or some sort of relative time delay in order to calculate an approximate position for the transmitter between the three towers. The towers already have this capability, as it is important in determining when to hand responsibility for a call off from one tower to the next, and which tower is to get the responsibility. This is the method used by the Triangulate Decker utility when the decker has penetrated a telephone system computer. Cell phone towers do not use directional antennas.

Here is a link showing current equipment and antennas used for locating a transmitter. http://www.rohde-schwarz.com/WWW/Publicat..../n170_eb200.pdf

[Spookymonster]

Most new cellphones in the US are coming equipted with a GPS locator. The intention is to make it easier for the police to find you in case you are:

a) in need of emergency care
b) suspected of criminal activity
c) not a member of the political party currently in power
d) a foreign national in a compromising position
e) all of the above

[Kurukami]

[Ol' Scratch]

Uhm, aren't GPS signal receivers passive? Or at least anonymous? How are they supposed to know you're you?

[mfb]

recievers are passive. if your reciever shows you as being 30 feet under the ice shelf, everyone else's will show positions relative to that.

[danbot37]

they are passive, in that the gps devices do not transmit anything, but they do track you. One of the possible commercial uses for it was talked about like this: It keeps track of where you are. you drive by your local weapons mart, and your phone emits a tone. You look at it, and its an ad for the weapons mart you just drove by.

[Zazen]

And when the distracting ad causes you to you crash into a tree, your phone automatically dials the nearest personal injury lawyer :P

[Frag-o Delux]

In some cell towers, I haven't been to all the carriers in america but a few have a machine called true postion. Which as the name implys it gives your cell phones postion. It is pretty damn accurate, and all you need to do is have the software on a laptop and plug it into the rack equipement, and know who you are looking for. Also a thing to remember is as long as your cell phone is on it is broadcasting a signal to the towers, most people think if you are not talking on it it is not doing anything.

[nezumi]

Some quick comments... I'm in no way an expert on cell phones (I do own one, but it doesn't have service, just so you know...) Cell phones are transmitting as long as they're on, which is why they are not the preferred method of communication among the truly paranoid (as opposed to beepers, which you cannot triangulate.) Cell phones can be triangulated in the way described by someone earlier (can't see the name now), or... you could just have two sensitive antennaes a few meters apart on your vehicle. Then you can follow a moving cell phone, since you're getting a constant feed. It won't be as accurate, but you don't really need it to be that accurate as long as you have a direction, right? From what I understand, GPS is NOT a passive receiver. It does in fact send something to the satellite. Otherwise, how would the GPS 'know' where you are? It doesn't have magnets or moon sensors on to tell your latitude and longitude, that's what the satellite is for. So I am pretty sure a GPS can be easily tracked. This is part of why a GPS is now considered an essential part of any adventurer's kit, if he gets stuck somewhere its very easy for the police to find him.

A random note, just so people are aware, GPS is legally not allowed to be as accurate as tracking a cell phone might be. The U.S. government requires that GPS has an error of approximately 6 meters, I believe. This might not be the case overseas, however.

[Zazen]

[Mr.Platinum]

If you have the new yen and you know the star is after you. Here is some advise
always buy a new cell phone after every run.

[Birdy]

Engineers to the rescue! ;-))

This is based on the european GSM system so the rebellious british colonies may vary.

A cell phone is periodically broadcasting a "I am here" message. This is picked up by one or more receivers. This message includes a code than identifies your SIM-card (the phone is the unimportant part here)

The receivers are connected by landline to a central control system (systems) and evaluate, who has the best signal strength. Your mobile get's assigned to that tower radio cell (hence the name). Think of it as an invisible area code. The telephone receives that information back ("You get a net") again choosing the strongest sender (Each sends a code/ID string).

At the same time that data is logged into a central computer system so the telefone company now knows in which cell you are. If a phone call comes in, it is routed (via land line) to that tower and broadcasted into the cell for your phone to pick up.

Cell size varies with telephone system with the old C-Net having cells in the kilometer range and moder E-Net or UMTS systems bracking it down to the hundret meter range.


Now for the tricks:

With the above one can only say "telefone X is in that area". But remember we said that occasionally more than one tower picks you up. That data is also stored, mostly to make sure you are not "dropped" when you leave a cell. At the same time the cells slightly overlap.

Now if you have only one cell (like my hometown) this does not help. But in the city you have multiple, small cells due to dead zones and obstacles (This is basically "line of sight" stuff) so you will be in more than one cell at a time.

By looking up the overlap and doing some calculation on signal strength (those cell phones are standartisiezed when it comes to output strength) the phone company can get a good estimate on your position (within 5-10 meters in a bigger city)

The GPS system on the other hand is a totally passive (and actually quite easily "barrage jammed") system. And in addition to that there is no way you can reach that satellite with any meaningful strength (There are other satellites that can hear your cell phone IIRC Rhyolyte) What some "Blockwarts" are proposing is this:

Your cell phone/PDA has a GPS linked to the phone. It uses the "Here I am, who hears me" packages your mobile already transmits and adds the GPS coordinates to them. Since your SIM-card already tells Brother Jackboot who you are, they now have your coordinates down to a meter or two (unless the US decides to degrade GPS performance again like they did until 1998 or so) Add the signal strength / cell overlap data from above and you are precise enough for the cops.


If you want to track down a cellphone yourself, there is a IRL system called an IMSI-catcher (IMSI is the protocoll used by your phone to tell the system "I am here") that acts like a really powerful/fast base station so your cell phone takes them as a base. The box can decode dialed numbers and numbers of origin so you know what phone called. Using more than one of this boxes (they easily fit in a small van) you can pull the same trick as the phone towers above.


This is actually quite simple. Even the Sowjet Army can do it. Ask that tschetschenian terrorist leader. Oops forgot. The Ruskis used that information and launched a massive artillery strike on him.

Michael

[Homme-qui-rigole]

Oh! Thank you everyone!

[Frag-o Delux]

Birdy cells work the same here in the states. Though most of the carriers I have done work for have their sites 3 to 5 miles apart. They say they pereffere 3 but sometimes a situation arrises that they have to go further out, but never more then 5.

[Birdy]

[Birdy]