undefined | Better HN

0 pointsAlupis4y ago0 comments

Part of the problem is the GPS resolution, which isn't accurate enough to know exactly which individual on a street has your stuff, or even which house it might be inside.

A long while back, on a early Saturday morning, I was awoken by my doorbell and accosted by an angry father of a crying daughter who had had their iPhone stolen by someone at a bar the previous night. Well, "Find My iPhone" showed the dot location of the phone was my house, so it must be me... turned out it was a neighbor two houses down - thanks Apple.

The best GPS resolution available to civilians is about 8 meters (26 feet) - and that's under the best, most ideal situation using the best GPS receiver and a large antenna... things a small cell phone in a pocket or bag doesn't have.

Cell tower triangulation isn't much better either... although the two used in unison can provide better resolution, but still far from good enough to pinpoint an exact individual, or even house (if the device is near an exterior wall, it may appear to be in the neighbor's house).

Police can't exactly go up and search people on the street because some Apple service says somebody within 20-40 feet or whatever might have the device - doubly so for searching a vehicle or house without a warrant.

So, while these devices are great for personal use - they probably cannot be used for real law enforcement purposes.

0 comments

_s4y ago

> The best GPS resolution available to civilians is about 8 meters (26 feet) - and that's under the best, most ideal situation using the best GPS receiver and a large antenna... things a small cell phone in a pocket or bag doesn't have.

I am not sure where you got this from but that is incorrect - the accuracy (or resolution) depends entirely on the number of satellites and/or augmentation systems you're tapped into, and how strong / clear those signals are. It can vary from a few kilometres down to a few centimetres.

Back in the 90's "Selective Availability" was a thing but it has since been removed.

See https://www.gps.gov/systems/gps/performance/accuracy/

Also - most modern phones can and do tap into the major providers (Galileo, Glonass, GPS etc), towers, WiFi spots, beacons and use all of these to give a a VERY accurate position of where the device is.

Edit: Might mention I worked first hand on indoor tracking of users, and a warehouse project for optimising worker picking - we were able to easily distinguish where a person was in a busy retail setting down to which section of a clothes rack they were selecting clothes from, and exactly where a worker was in a very interference-heavy (metals) warehouse floor using the above mentioned technologies.

AlupisOP4y ago

From your link:

> For example, the government commits to broadcasting the GPS signal in space with a global average user range error (URE) of ≤7.8 m (25.6 ft.), with 95% probability. Actual performance exceeds the specification. On May 11, 2016, the global average URE was ≤0.715 m (2.3 ft.), 95% of the time

Which assumes clear skies and good line of sight... Neither condition exist inside your pocket or house.

Regardless, none of the technologies you listed are accurate enough for police to legally search a person or their home simply because some tech company says a device is located around some dot on a screen.

PS: Your warehouse tracking thing is interesting, although I think you'd of had an easier time tracking gyroscope/accelerometer senor data.

ViViDboarder4y ago

From your quote:

> Actual performance exceeds the specification. On May 11, 2016, the global average URE was ≤0.715 m (2.3 ft.), 95% of the time

1 more reply

w0mbat4y ago

This is true, but irrelevant to discussion of AirTags. AirTags give much finer grained location once you are close, as it uses the new iPhone's ultrawideband hardware to give you accurate bearing and distance to the tag, based on live information.

PurpleFoxy4y ago

What police should do is keep a record of reports and their location and if too much shows up on one address, they investigate.

I have also seen reports of actual police knocking on people’s doors looking for things that show as on their house but we’re inaccurate.

j / k navigate · click thread line to collapse