You don't get that level of granularity by merely triangulating cell tower pings. Sounds like they got GPS location data from people's Google accounts.
select * from mobile_location where latitude between 38.88778433380732 and 38.891917997746894 and longitude between -77.01269830654866 and -77.00613225870377 and epoch_timestamp between 1609954200 and 1610067600
Returned quite a number of mobile devices accurate to the meter. Was fun to see which phone was in which room or blade of grass of the building. I'm not even American.
I hope your employers keeps track of stuff like this.
[1] https://nrkbeta.no/2020/12/03/my-phone-was-spying-on-me-so-i...
I'm genuinely asking, I have never seen such a setup.
1. Absolutely yes for ad hoc queries and there's a wealth of logging and privacy features built into all of our tools.
2. Absolutely yes and those queries are audited. For any query that matches some heuristics it'll warn us with a big scary message to make sure the query is legitimate work.
For the query linked above about checking who was around a location at a given time I'd probably be fired before the query completed. It's a pretty comfortable job but they don't mess around with user data, it's zero tolerance if it's abused and even if there was never a warning message your ass is still out the door when they catch you.
For all the flak tech giants get around PII I think it's horrifying that smaller players can still get hordes of sensitive data and yet have basically no safeguards to prevent misuse like querying whatever some internal engineer wants to look at.
I guess this part answers the questions of "why", "what" and "does the employer care". Well, at least these people now know what they did "not" have to hide the whole time.
>Multilateration should not be confused with triangulation, which uses distances or absolute measurements of time-of-flight from three or more sites, or with triangulation, which uses a baseline and at least two angles measured e.g. with receiver antenna diversity and phase comparison.
[1] https://www.verizon.com/about/news/how-far-does-5g-reach
[2] https://www.celltowerleaseexperts.com/cell-tower-lease-news/...
[1] Give it a few minutes and it'll pin point where my desk is inside my office.
It does some real dark arts physics wizardry to compute a position. Nothing like that can be done for cell phone signals.
But the math is not significantly harder. The only meaningful quirk is that without a perfect clock you don't know the exact distances to each satellite, instead you have distances a+n, b+n, c+n, etc. Still though, you're just looking for the spot where your numbers line up. There's no wizardry in the "compute a position" part of GPS.
In the end the math is indeed similar, but how it gets there is quite different.
For one thing, each satellite carries an atomic clock to make things work. And the receiver locates itself by listening to signals, while triangulation is several receivers working together to locate a transmitter.
The only substantial difference is that in case of GPS the calculation happens on the receiver side (GPS signals only go in one direction), while cellular service providers calculate time advance on the tower side.
Maybe there is an element of triangulation in that, but it's far less precise and ambitious than GPS.
Once you know which tower the phone is connected to, coordinates of that tower, antenna pattern, and distance (from timing advance and speed of light), you can calculate approximate cell phone location.
You get more data if the phone moves or propagation changes and phone changes towers. In urban environment with many towers location obtained this way can be very precise. Not as good as GPS, but good enough to within a block.
This is a simplification. Real systems also use signal strength, take into account multipath propagation, and apply some filtering from physical constraints (how fast a cell phone can move).
Your link is for GSM and states a 550 meter resolution, but I tried looking up LTE and I think it said 10 meters there.
I also understand modern (maybe next generation) towers will use directional transmission to avoid sending signals in all directions. Even if that's a 20° beam, that narrows don't the location by a lot.
You need to lock with multiple satellites, I assumed this was for triangulation.
LOL
Lower cost prepaid carriers are also pushing 5G phones heavily (albeit somewhat crappy ones), and offering them for free.
Notice that all of this is entirely legal, above board, and you agreed to it as part of your service agreement.
Source: I worked for AT&T and Carrier IQ
"Agree" implies willful consent and being in harmony with the implied outcome.
People accept because they have no meaningfully acceptable choice - which is the exact target that carriers aim for.
But even using timing advances, if the cells aren't too big, you get a pretty reasonable accuracy.
Also consider that more than 3 stations probably were nearby.
It's an awesome, deep and nuanced topic certainly not suited to a political HN comments section. "Timing Advance" is the probably the jumpoff keyword for anyone interested.
Mobile towers also use beam-forming in two directions and have a few other techniques to get better signals, the metadata involved with these things (if kept) essentially drops the error range down to GPS levels if not better.