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Why do people keep coming to this couple’s home looking for lost phones?

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Re: Why do people keep coming to this couple’s home looking for lost phones?

#11

Post by mapgrep »

JonnieCache wrote: post #10
mapgrep wrote: post #9

My money is on a wifi SSID that matches the one used by thieves or a heavily-trafficked location the victims all pass through. My company moved ~5 blocks and it really screwed up the map on my phone (which I use to get around the city) for several months. My company had left the network SSID the same in the old location, so that no one had to re-configure their wifi. Even with GPS on, my phone was always convinced it…

I thought it was the MAC addresses of routers which were used for mapping, not SSIDs. Duplicate SSIDs are very common.

Good point. My understanding is that both SSID and MAC address are typically used as inputs: https://en.wikipedia.org/wiki/Wi-Fi_positioning_system

Re: Why do people keep coming to this couple’s home looking for lost phones?

#12

Post by lorenzhs »

JonnieCache wrote: post #10
mapgrep wrote: post #9

My money is on a wifi SSID that matches the one used by thieves or a heavily-trafficked location the victims all pass through. My company moved ~5 blocks and it really screwed up the map on my phone (which I use to get around the city) for several months. My company had left the network SSID the same in the old location, so that no one had to re-configure their wifi. Even with GPS on, my phone was always convinced it…

I thought it was the MAC addresses of routers which were used for mapping, not SSIDs. Duplicate SSIDs are very common.

The display name is often referred to as ESSID while the MAC address is also called the BSSID. Confusion!

Re: Why do people keep coming to this couple’s home looking for lost phones?

#13

Post by JonnieCache »

mapgrep wrote: post #11
JonnieCache wrote: post #10

Earlier quoted context omitted.

I thought it was the MAC addresses of routers which were used for mapping, not SSIDs. Duplicate SSIDs are very common.

Good point. My understanding is that both SSID and MAC address are typically used as inputs: https://en.wikipedia.org/wiki/Wi-Fi_positioning_system

I guess it's not exactly difficult for the likes of google to remove the millions of 'Netgear' SSIDs from their dataset.

Re: Why do people keep coming to this couple’s home looking for lost phones?

#14

Post by mikeash »

mapgrep wrote: post #9

My money is on a wifi SSID that matches the one used by thieves or a heavily-trafficked location the victims all pass through. My company moved ~5 blocks and it really screwed up the map on my phone (which I use to get around the city) for several months. My company had left the network SSID the same in the old location, so that no one had to re-configure their wifi. Even with GPS on, my phone was always convinced it…

An amusing example of this sort of problem shows up sometimes on airplanes with onboard WiFi. If the phone doesn't get a GPS lock right away (common when you're in a metal tube) then it may show the position based on the mapped location for the hotspot MAC address, which is often at a completely different airport.

Obviously, Skyhook isn't driving around mapping airliners, but I think these days they have the mobile devices themselves do the mapping, by phoning home with the WiFi hotspots it sees while out and about.

Re: Why do people keep coming to this couple’s home looking for lost phones?

#16

Post by RyJones »

JonnieCache wrote: post #2

Now this is interesting. Presumably the coordinates of their house are significant in some way. The result of some kind of truncation perhaps? I can't see how a floating-point error could converge on a specific value like this, but I'm no expert in such things. If they could only post their address the answer would surely be found very quickly, but that would defeat the object somewhat. I suppose it's fortuitous that…

I have pictures I take in Idaho turn up in Mongolia due to a sign error - these are taken with the default iOS photo app.

Re: Why do people keep coming to this couple’s home looking for lost phones?

#17

Post by seiji »

JonnieCache wrote: post #2

Now this is interesting. Presumably the coordinates of their house are significant in some way. The result of some kind of truncation perhaps? I can't see how a floating-point error could converge on a specific value like this, but I'm no expert in such things. If they could only post their address the answer would surely be found very quickly, but that would defeat the object somewhat. I suppose it's fortuitous that…

Sorry, but it's actually really simple.

It's the same reason why on a Jet Blue flight, my phone shows me geolocated to Long Beach, CA for the entire flight (if I don't hold the phone up to the windows).

Phones prefer wifi positioning, and that's based on the base station mac addresses. If you are in a highly wifi dense area, moving one AP can auto-propogate its new location by phones reporting in bulk groups of mac addresses they scan at once back to your location provider. ("30 mac addresses detected are know to be in Dublin, but one mac address detected is known to be in New York. Let's update the New York mac address to be Dublin now.")

The auto-location-updating is one reason SkyHook wireless died. Once they did the initial scanning, the entire wifi location database can be made reasonably self-updating (and other correlative updates can happen with your drive-every-street-in-the-world mapping vans much less often.

Wifi position is more accurate than GPS positioning (plus, faster to locate and less power intensive), so it's always preferred first. GPS positioning is worse (accuracy/power requirements), so GPS tends to be a fallback if you're in a "broad location" category like cell tower only positioning or zero-location positioning (airplanes, mountain tops, etc).

Re: Why do people keep coming to this couple’s home looking for lost phones?

#19

Post by mmagin »

mapgrep wrote: post #9

My money is on a wifi SSID that matches the one used by thieves or a heavily-trafficked location the victims all pass through. My company moved ~5 blocks and it really screwed up the map on my phone (which I use to get around the city) for several months. My company had left the network SSID the same in the old location, so that no one had to re-configure their wifi. Even with GPS on, my phone was always convinced it…

Well, BSSID, not the easily-changed ESSID (as commented below.)

Presumably some manufacturer of ultra-cheap wifi gear isn't properly setting a unique BSSID range into the units they make, and some stolen-phone operation has the same BSSID as these folks do.

Re: Why do people keep coming to this couple’s home looking for lost phones?

#20

Post by patrickmay »

I found this particularly disturbing:

> In June, the police came looking for a teenage girl whose parents reported her missing. The police made Lee and Saba sit outside for more than an hour while the police decided whether they should get a warrant to search the house for the girl’s phone, and presumably, the girl. When Saba asked if he could go back inside to use the bathroom, the police wouldn’t let him. > > “Your house is a crime scene and you two are persons of interest,” the officer said, according to Saba."

The police shouldn't be able to detain someone for over an hour without probably cause and without arresting them.

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