How Cell Phones Reveal Your Location - Computerphile

[@TechyBen]

I actually had a friend complain about his hands free cutting out while driving. Then I reminded him he was talking on a wireless device, with someone 100 miles away, while driving at 70mph past multiple towers and everyone else possibly doing the same. It was amazing that he could do all this in the first place. :)

[@kasuha]

It's not all. If you're talking or transferring data, not only your current station knows in which sector and how far you are, it even knows how strong signal your phone has to other nearby stations. The phone measures it and reports it to the station so it can decide when you should switch to another station. That also allows to pinpoint your position rather precisely. When the phone is just switched on, though, it talks to the station very rarely and does not send those measurements. Then the station just knows you're somewhere within its area and does not even know the distance since you may have moved significantly since last time it talked with your phone.

[@ratdude747]

One of my EET professors actually does cell phone forensics in court cases... this is pretty powerful (albeit usually circumstantial) evidence when properly presented.

[@tobortine]

Professor McAuley should be hailed as a whistle blower for informing us about how the phone suppliers sell our locations to the shop keepers. He's probably packing for a flight to Moscow right now.

[@KSITREVS]

feedback loop hmmm

[@HKragh]

As he said, they are not selling YOUR location, but statistics

[@tobortine]

Henrik Kragh I was being light hearted don't take the comment too seriously.

[@EllinonEnosis]

Nothing new actualy....you (most people) just found about this now...

[@qdfxrg]

Or not.

[@ItsThe1300]

Very interesting video! I had never really thought about the base stations splitting their reception into time windows for each phone but it makes perfect sense. Very informative! Keep it up!

[@victorbrandt2202]

yes this process is called time division multiple access

[@thejumperkin]

Beautiful explanation of something I was very interested in.. At least the mobile phone communication part (hadn't considered that many factors on mobile communication at all..). Such an informative video Wondering why KZbin took so long to suggest it to me lol Thanks

[@Triantalex]

??

[@antivanti]

At 4:15 This speed limit is also the main reason cellphones had to be turned off on airplanes. Not because of air safety but because it confuses the GSM network. Also way up in the air it is hard to determine what cell tower below is closest to your phone which further confuses the system.

[@antivanti]

Probably not. However I understand that they wanted to test that stuff out thoroughly before allowing such devices. Mythbusters tested it once as I remember and I think they actually found a display used in some planes that could get some interference from cellphones which is crazy because you'd expect those to be even more robust than normal consumer level displays which are definitely not affected.

[@victorbrandt2202]

no GSM is public land mobile network (PLMN)system,cant be used while in air or at sea.

[@DaveScottAggie]

I didn't realize that the cell tower data could be used to estimate traffic congestion. That's neat.

[@wisteela]

Vodafone have recently started using the data for this

[@Zimpfnis]

Awesome, thank you for another interesting video!

[@dannycraps]

This is why I walk around with a tinfoil hat 0_o lol

[@georgeryandev2103]

Way ahead of your time man.

[@Triantalex]

ok?

[@GunSinMovies]

Do cellphone towers never have overlapping coverage? They can get a much more accurate location of a phone by measuring the distance from 2 or 3 towers.

[@joe.savage]

If I remember correctly, GSM base station coverage commonly overlaps (with varying signal strength - your phone choosing the strongest signal) and this is used exactly as you describe to further narrow location data.

[@smgibb]

Yes, coverage overlaps. I used to work for a company that did network based mobile location technology. They specialized in UTDOA locations. Basic run down is that given a signal and two towers receiving it, you can draw a curved line where that signal had to originate from. Add another tower, and you can draw another line, add another tower and you can draw a third line. Where all the lines intersect is where the phone is. More towers means more lines, which means more accuracy. An expensive system, but worked really well provided there were enough towers that could get the signal. Was/Is a good alternative to GPS when you can't get a GPS signal. Plus it's good for not relying on the handset to report the location data. Provided the phone was on, we could find it. AT&T and T-Mobile were the primary customers. Not sure how they are doing now, it's been a few years.

[@OoJxShadow]

Joe Savage Yes, you can then use the power of the received signals to compute a pretty accurate location.

[@rich1051414]

The more overlapping coverage, the more accurate it is. You need 3 distance measurements to get an accurate estimate of your location. With only 2, they can only narrow your location down to a fairly large region, but that still is usually all the help police need to figure the rest out.

[@rogerwilco2]

Yes. The first iPhone, before the iPhone 3G added GPS used this to figure out where you were. It was often accurate enough for google maps navigation. It's why the phone was only GSM, not CDMA, and why Apple needed special contracts with the providers.

[@Kadderin]

What's the difference then from GSM to LTE/CDMA when using these tracking methods?

[@MrOmnos]

Hahaha. ..its funny to see how people are getting surprised by this tracking thing...its not that new technology. ..its old and is used very often...few years ago...my friend ran away...he parents were really worried....lol...he was tracked in less than 3 hours by police. ..they tracked his phone!! And he had no gps on his phone...there's a protocol on gsm network that can used to triangulate you...it has been used by law enforcement for ages now!! :p

[@StalkyWasTaken]

You're right, we see it a lot in the movies aswell, one thing I don't get is why people are upset about revealing their location. Unless you're lost or you're a running criminal it has no impact.

[@MrOmnos]

lol...these people are worried about that their locations..I mean why do they even care....I bet most of them post their locations with their each and every status updates on Facebook!! :P

[@smgibb]

Depends on what you mean be "locate". Accuracy to within a general area, yeah you can do some relatively simple calculations to get a general area. Further after the fact analysis can be used to narrow it down. But cell phone companies weren't using really accurate locations until after E-911 standards were implemented. Accurate (within feet), realtime, non-GPS locations are really expensive and not easy to do. I used to work for a company that provided the equipment and services for that sort of thing. So you're talking early 2000s when cell phone companies started implementing that sort of thing, and even then as of the late 2000s, they were surprisingly lax about it. I remember seeing some stats around 2008, and you'd be surprised at how often a big cell phone company didn't have the equipment in place to locate a person accurately enough to forward an emergency call to the correct 911 call center.

[@antivanti]

Pretty much everyone knows that they can figure out what cell tower you are connected to but perhaps not that they can get a fairly precise distance as well as direction using only one tower.

[@Slithy]

And that's why i always pull out the battery after i rob someone. JK.

[@xanokothe]

In computer engineering, we learn all these thinks... TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access)...

[@chopinbloc]

Xano Trevisan Kothe True, but I was under the impression that time division wasn't really used anymore, that carrier sense multiple access collision avoidance was preferred, in combination with orthagonal frequency division multiplexing.

[@AlanColon]

Derek, when you don't get a GPS signal on your phone, or have GPS switched off, it still has a rough idea where you are. How does that work?

[@florencetown4024]

02:00 when he spoke about gsm net work that is fascinating how it works

[@KarmicBeats]

The accuracy of location data from cell phone towers is increasingly coming under fire. It turns out that they cannot give a very accurate information. This is becoming an issue in legal cases where that info is used to try and say where someone was a certain time. In one case someone was convicted of murder. On appeal they proved their innocence as a call just minutes prior to the incriminating call, showed them 20 miles away. That is one call showed them in the area of the murder, while a call a few minutes earlier showed them 20 miles away. Cellphone tower data is completely unreliable for pinpointing persons location even to a large general area.

[@flat-earther]

hi karmicbeats, have you become a flat earther yet?

[@patrick1020000]

How long ago did the ACLU release the previously NDA'd Florida court documents on the use of Stingrays?

[@thany3]

The problem is that phone companies *can't not* know where you are, becasue it's instrinsic to the system. This must include 3G and 4G connection as well. If I'm not mistaken, 3G and 4G cell antennas have a shorter range, because of the frequency being higher. Shorter range means it's possible to serve more phones at once, but it also means those phones can be geographically located to a finer degree... Scary. Because I have no way of knowing what my phone company does with my location. And turning it off is impossible. And there's no opt-out - there couldn't be.

[@hellterminator]

“… I have no way of knowing what my phone company does with my location.” Try doing something nobody seems to do anymore: read the T&C.

[@thany3]

The T&C tell you only so much. They will tell you what the company is doing with your data, but it won't tell you what the company doesn't allow itself to do with your data. Also the T&C won't tell about things they can and can't do with your data that are already covered by laws. Lastly, T&C (from any company) are always deliberately written in such a way that no normal person is able to understand them. And frankly, I shouldn't have to be an educated lawyer simply to understand the T&C that comes with my provider contract. You might even sue them for not writing out in normal sane human-readable text what the hell they mean by all that legalese.

[@bryanjconlon]

Question please:. Could a Mobile phone user be tracked and followed on the move or does the "follower" have to be based somewhere static with lots of tech tracking equipment? For example, could I follow someone with a significant distance between us and identify where his route is and ultimately find his final destination using some kind of smartphone app?

[@chasingsunsets9901]

I know with iPhones you can turn on someone’s location to your cell by sharing their location through your contact info they have you under in their phone. Just go into their phone, go to your contact they have you under, then click “share location indefinitely”, & then you will always know where this person is. Now when the cell is turned off, I’m not sure how long it will last for, I think 5 minutes after the cell was turned off. I share my location with my bf so this is how I know this information, lol.

[@bryanjconlon]

@@chasingsunsets9901 thanks for sharing that with me.

[@flat-earther]

hi bryanjconlon, have you become a flat earther yet?

[@rogerwilco2]

This is how the original iPhone figured out your location, before they built in GPS with the iPhone 3G. It was pretty accurate given the limitations of the technology.

[@flat-earther]

since satellites in space orbiting a fantasy globe earth in a vacuum do not exist, this may be how GPS actually works. They may also use high altitude balloons.

[@sparrtak]

What about 3g or 4g? Does UDP or TCP pass location data?

[@khkrasua]

Would be interesting to see how the Computerphile professors react to Watch_Dogs similar to how the SixtySymbols professors reacted to Portal...

[@NumptyGrumble]

With the ethernet systems the length of cable was limited (eg 200m for 10Base2) and terminated with a set impedence to prevent reflections which is why collision detection was practical. With radio waves its not possible to do this and signal strength will vary depending on local conditions like surrounding hills/buildings and the weather (eg raining). Satellite systems have the same problem. Think there were plans to produce a mobile network based on Satellite network in the 90s. Kind of interesting to speculate how the owners of of the satellite network would do with location data at a global rather than national level.

[@camfg8908]

Can you trace a mobile phone that has been reset to factory settings, and does not have sim card, but is using wifi networks for connections?

[@flat-earther]

maybe

[@wexer82]

first of all, thanks for approving this comment. secondly, great video.

[@TheEPROM9]

I don't like being tracked, it's one of the reasons I never have my phone on me.

[@saeedurrahman2056]

No if you made a call and it last below 10 seconds ( approximately ) they can't track you

[@yfs9035]

@@saeedurrahman2056 you don't have to make a call, because we are always connected to data services with 3G and 4G. Airplane mode would suffice (as long as it actually disables the radios)

[@iTwIsTeDZz]

Take it if you need it and put it in a Faraday cage. Problem solved

[@Triantalex]

ok?

[@arayashikinoshaka]

I always thought it was a triangulation thing done with various antennas

[@Feyangel23]

I just realized this is how robots, stations, and vehicles work in space missions

[@flat-earther]

hi feyangel, have you become a flat earther yet?

[@EcceJack]

I recall that at least two of my old mobile phones (cell phones, or however you decide to call them) had shown, on the main screen, just under the network name, or clock, or something, a rough location. And I found it quite interesting. That was back in Slovenia, and I'm not sure how the privacy things are sorted out there, but even here in the UK the phone was at least able to give me the area code (say 01223 when I was in Cambridge) - you as the end user still need a map of area codes to work out your location from that (and the accuracy is much lower than for the other system), but it does seem that it's possible - at least in principle - to have some of this location info available for the end user. ......Mind you, my shiny new smartphone isn't as smart as that and can't figure out its location without GPS or at least WiFi.

[@AlanColon]

Really?? You couldn't let CGP Grey have a 0 count on the Brady vs. Grey app for even 1 hour?

[@samramdebest]

it even hasn't updated jet, it still says 22

[@AlanColon]

samramdebest I know... Grey will be so disappointed :-)

[@samramdebest]

Alan Colon Maybe they are doing a podcast right now

[@AlanColon]

samramdebest *facepalm* of course! I bet you're right, and Grey saved his release for the podcast like Brady did with Epic Circles. Although, given Grey's stress levels about releasing videos, it'll be interesting to hear him sweat.

[@boosiv]

? what am I missing, I don't understand what you guys are talking about.

[@sonofawil]

Question: If you wanted to create a local network to position your phone/tablet to within a 10 cm and determine its orientation how would you go about it?

[@yfs9035]

10 cm is too accurate, but now it would be possible to use Bluetooth and Wi-Fi beacons. I believe somebody has made some projects based on this on GitHub

[@oussamakassah2669]

I think you can also triangulate the position by using 3 towers and their relative distances to the mobile phone.

[@BlueBirdBaby]

QUESTION: This year only i have noticed cell phone location turning on, by itself. Why could this be? Location, in settings, has all permissions switched off. It is annoying. And sometimes i catch it turning itself off right as I wake it up. Please be honest, i would like to know. Does this have to do with anything important? How might i prevent it?

[@flat-earther]

IDK, did you figure it out? BTW rubyrosesong, have you become a flat earther yet?

[@skyleramato7487]

what about texts, is it transmitted the same way?

[@DhavalSri]

So this is how Google locates us without GPS? Also gives us traffic information (where it's slow or normal) ?

[@Nilguiri]

No triangulation from 3 or more towers, then?

[@rorybaxter534]

You can get triangulation and this is used to pin point your location in more detail. Your phone will be programmed to communicate with the strongest tower. When to overlap your location, your phone will mostly talk to the strongest one, but the other(s) will know you exist and all the other information.

[@yezper6828]

Yes, they do that too.

[@hpekristiansen]

It is called trilateration (look it up). Triangulation is something else.

[@Nilguiri]

hpekristiansen Ah yes, you're right. I stand corrected!

[@Triantalex]

??

[@jbrou123]

We should know that they could track us through your phone. There are many free aps and games in which you must agree to allow location services. By loading these freebies, we give permission for them to track us.

[@davidickadavidu7058]

What about when you're in a conference call? One host and many callers... Can u find'em all ?

[@WidyGraycloud]

wow I didn't know cellphones can be track by location very mind blowing

[@NSLikeableHuman]

It's even more mind-blowing when you realise that tracking (or at least "tracking") doesn't require an active call of a certain duration (like a minute or three)-a myth maddening me every time I see it in a film. On the other side, GSM tracking is rough. Many GPS systems (Assisted GPS) use GSM to quickly localise roughly until the GPS mechanism kicks in, but the GPS signal is still required for navigation to be possible.

[@TheFloppmann]

Yeah the camera and microphone can be turned on without you knowing as well.

[@MrOmnos]

Floppmann tracking you is not a hard thing to do for telecom companies...they can track you even if your phone has no gps..they can triangulate you..if you are on network...turing on camera or microphone requirs those services runing on your device...to run these services remotely you need to install some kind of malware on the phone...so its hard to turn on your camera or micro phone unless you are totally stupid and get youself infrcted!!

[@ghelyar]

***** My pet hate with technology in films is the sound that progress bars make. On mobile devices you also need a data connection to actually calculate routes. Unlike dedicated satnavs (TomTom, Garmin, Mio, etc), the phone doesn't do it internally. If you go somewhere with no phone signal it's about as useful as a hot brick, and you generally don't find out about that until you're totally lost.

[@CTCCoco]

Protip: if you don't want to be tracked down don't use a mobile phone or anything similar.

[@leelemon3373]

So this is why some of my calls are dropped because one of us is in a car moving. Got it. Thanks

[@flat-earther]

hi leelemon, have you become a flat earther yet?

[@deepsheep9102]

So, we can expect speeding ticket on our cell phone bills in the near future. Good to know.

[@PontusWelin]

What about triangulation? If you are close enough to two or more towers, can't they get a very exact position?

[@Mobliz]

Skype still publicly reveals IP address information through a massive structural bug with the only requirement being knowing the skype id of the user. with it, they are able to determine real-time ip address and location down to a few blocks of any user logged into skype.

[@R1ckr011]

Oh...fuck lol. But is it a Bug... or a Feature? (*cough* NSA)

[@captainzork6109]

Do you have a source on that?

[@Mobliz]

www.zdnet.com/blog/security/skype-knew-about-ip-address-security-flaw-back-in-2010/11837

[@captainzork6109]

Thank you very much, for your answer~

[@papst97]

What about triangular tracking with 2 or more towers???

[@ZER0--]

There have been many times when Ive woken up after a heavy night and would love my mobile to tell me where I was.

[@r05ejan8]

Nice voice!

[@chongjunxiang3002]

I thought it only happen in video game just like watchdog.

[@salat]

No word about handover/cell roaming ?

[@WistrelChianti]

That sudden desire to turn the phone off...

[@flat-earther]

hi wistrel, have you become a flat earther yet?

[@hitechinvestigations]

Anyone on here clued up with mobile phone networking systems and particularly BTS, please get in touch as doing some research and could do with some info

[@monkemode8128]

Imagine getting a speeding ticket because your phone company ratted on you for going too fast

[@flat-earther]

hi monkemode, have you become a flat earther yet?

[@monkemode8128]

@@flat-earther I was a flat earther well before your parents even met. Don't lecture me boy.

[@flat-earther]

@@monkemode8128 okay. BTW monkemode, what do you think about all gubments drawing a line around you(Antarctic Treaty) and saying you are not allowed to leave? If you don't know what I mean, read my about tab.

[@MADagain]

If the phone companies are monitoring me and knowing that its me... i think this is a hugeee invasion of privacy... good thing i never use my phone and its always at home :)

[@TheWindsTwelveQuarters]

So is Angry Birds. Watch out.

[@isgdre]

hey, No brown paper. Good replacement though given the channel.

[@rogerwilco2]

This channel has used the chainlinked printer paper from the start as far as I remember.

Ohh I thought that in the mall I was that they used Wi-Fi to track me very interesting very watchdogs

[@yurilsaps]

Please, put the subtitles!!!!

[@milesdyson5211]

Can a phone be tracked and identified from a cell tower ?

[@yfs9035]

Yes he just explained this

[@Seawolf159]

I am sorry i am lazy as truck. So is it right in the movies, they pop the battery out or change the sim, does this stop them from finding you?

[@chopinbloc]

Sea Wolf Removing the battery will definitely take the phone off the network. Anything short of that and "they" can still do anything they please with your phone.

[@Milosz_Ostrow]

Simply shutting the phone off or putting it into "airplane mode", i.e., disabling the phone's WiFi, Bluetooth and telephone radios, is usually sufficient. You can take the batteries out if you're paranoid, but most new smart phones have non-removable batteries. In that case, wrap the phone in a layer of aluminum foil.

[@georgievvladimir]

What about your location in case of NO GPS and airplane mode. Just go home and turn on the WiFi only. Then start Google Maps. You will wonder that Google know your exactly location. Please, note that you can not find your location based on your IP address using any web page... Then how Google know where you are ?

[@notagoose4400]

you can locate where you are based on your ip its called geolocation

[@GaryKildall]

We live in a Big Brother world. And we enjoy it until it is too late. There is no return. It is just a matter of fact and time before we are judged without law.

[@guilhermeperazzini]

If take the battery off they still can track??

[@flat-earther]

I think no

[@JustinKoenigSilica]

so watchdogs is bs, you'd get tracked in 10 minutes.

[@heheheheheeho]

I don't care at all if I'm being watched. I haven't done shit so why even bother caring lol

[@hellterminator]

Here's a reason: I'm peacefully strolling through the downtown when suddenly my phone beeps. Someone sent a message! What could it be? It's not my birthday, so definitely not a congratulation. Does somebody need me to do something? Do I even want to find out? But what if something bad happened? Did somebody die? What if something good happened? Tentatively I pull the phone out of my pocket and unlock the screen. “You're near to the shopping mall XXX. If you shop there within the next two hours and show this message to the cashier, you will get 10% discount.” Fucking SPAM!

[@heheheheheeho]

***** That will never happen. It just won't.

[@hellterminator]

tokfrans Oh, you didn't understand. That's not a hypothetical scenario, that's what happened to me last Thursday.

[@DaffyDaffyDaffy33322]

tokfrans Here's a general rule of thumb when it comes to advertising. If it exists, there are people working to get their logo on it.

[@fetchstixRHD]

hellterminator: To add, I changed networks not that long ago, and occasionally go near or to airports. Funny enough, whenever I do my network texts me about roaming prices, asking if I'm heading abroad 🤔

[@AvGeekLucky]

For more complete tracking (for shopping malls for example): wifi mac addresses.

[@narcissecardinal1172]

Can they track texting app

[@thebareminimum9289]

I knew this was ancient history when I clicked on it. The other day, while covering the sat/northstar antenna on my truck with heavy foil tape I asked myself what the heck am I doing. I try not to even J walk anymore.

[@flat-earther]

hi thebareminimum, have you become a flat earther yet?

[@MrTheAer]

Ey, what about triangulation?!

[@tabularasa0606]

They can't they can only reveal the location of the cell phone. They can't guarantee that you are actually carrying it.

[@DFX2KX]

usually that's a pretty good guess to assume you are. unless you're being unduly clever and dropping it in someone else' pocket to foil the fuzz.

[@tabularasa0606]

I never have one with me, so it will only reveal my location when I'm at home.

[@rinu123]

I've used a positioning service to locate my phone when I lost it. It was available at my mobile operator's website. It must have been about 5 years ago. The accuracy was terrible.

[@becu3457]

GOOD

[@CodyGall]

2:30

[@PratyushBhattacharjee-yf9mi]

Sob got my all confused n s*it

[@ezemoney2497]

Thanks for the recommendation ma'am bulbtools on Instagram is really a life saver

[@sarasam6392]

This can be used for coronavirus.

[@yfs9035]

Why?

[@sarasam6392]

YFS to find all people with coronavirus

[@anti-vaxxer]

hi sarasam, have you become an anti-vaxxer yet?

[@ZipplyZane]

So nothing about triangulation, using two or more cell towers to narrow down your location even more?

[@porkypine1888]

:O

[@AmiyaPatanaik]

The confusion between GPS and GSM is strong on this one....Guys both are different technologies please don't confuse....

[@truthprevail2742]

It is not clear

[@flat-earther]

what?

[@StephenMortimer]

I am shamed! A guy somewhat my age has a grasp on all of this! Brady this is somewhat damaging for my ego!!

[@emeraldsummers6006]

It makes people feel raped

[@flat-earther]

hi emeraldsummers, have you become a flat earther yet?

[@kingamongpawns1]

i dont own a smart phone. my phone doesnt have wifi internet or a camera. all it does is text and call. like he said tracking is a given when u have a cell phone. its how they work. my whole life is not in my phone just a few numbers & i normally only call my wife. that info is worthless.... have at it hoss

[@adameve1280]

I highly recommend _60_cyber_s to y'all

[@MrOmnos]

Hahaha. ..its funny to see how people are getting surprised by this tracking thing...its not that new technology. ..its old and is used very often...few years ago...my friend ran away...he parents were really worried....lol...he was tracked in less than 3 hours by police. ..they tracked his phone!! And he had no gps on his phone...there's a protocol on gsm network that can used to triangulate you...it has been used by law enforcement for ages now!! :p

[@adameve1280]

I highly recommend _60_cyber_s to y'all