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How does Google know where I am?

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Re: How does Google know where I am?

#91

Post by dogma1138 »

GrumpyYoungMan wrote: post #90
leot wrote: post #11

Earlier quoted context omitted.

Do you have a citation on phones using inertial navigation?

Research has been done before on using the gyro + accelerometer on a smartphone as an IMU (inertial measurement unit) to augment positioning; see for example: http://gpsworld.com/showing-smartphones-the-way-inside/ However the last I heard, powering the gyro + accelerometer constantly was a prohibitive drain on the battery and the relatively low grade sensors used in smartphones made the positional drift rate high en…

Google has been supporting this since API version 10, this is the default (and only) location provider if you are using the Google Play Services API. https://youtu.be/Bte_GHuxUGc?t=400

Then skip https://youtu.be/Bte_GHuxUGc?t=700 to for the deep dive :)

You can still do location "manually" by either using GPS or sensor data using the Android framework.

Re: How does Google know where I am?

#92

Post by [deleted] »

spyder wrote: post #76
slim wrote: post #55

If I understood correctly, android downloads nearby BSSIDs with corresponding Geoposition when internet connectivity is available, to use them when no connectivity is available. It should be possible to reconstruct google's BSSID database, right?

Yes and there are multiple databases available on the net: http://openbmap.org/ https://openwifi.su/?lang=en https://wigle.net/

[deleted]

Re: How does Google know where I am?

#93

Post by cpeterso »

Mozilla built a crowd-sourced database of Wi-Fi, cell, and Bluetooth network locations, collected by volunteers running an Android "stumbler/war-driving" app. I helped start this project for Firefox OS, which is mostly defunct but the Mozilla Location Service (MLS) is still used for Firefox Nightly and DevEdition on the desktop. :-) Here is a zoomable map of the location data coverage:

https://location.services.mozilla.com/map

Mozilla exchanges the cell location data with the OpenCellID project. Mozilla's cell database is available for download here:

https://location.services.mozilla.com/downloads

For privacy reasons, the Wi-Fi and Bluetooth databases are not currently downloadable, but they can be queried through a web service API:

https://location.services.mozilla.com/api

Re: How does Google know where I am?

#94

Post by jhayward »

sly010 wrote: post #25
comboy wrote: post #17

Earlier quoted context omitted.

Are you sure they do that when wifi is off? I was under the impression that it only happens when wifi is on (and it seems to me that my location on the map is more stable with wifi on). That would be very not ok if it would happen with wifi off. I turn my wifi off to save the battery, and it wouldn't do much if it was still looking for broadcasts.

Its a question of terminology. When you are passively listening to (periodic) SSID beacons, you are not transmitting anything, nor consuming any energy on your radio. One could do that even in airplane mode. It's very different from when you hit "scan" and are actively sending broadcast packets on every frequency and waiting for the wifi routers to (actively) answer. Which really only happens when you pull down the l…

> or consuming any energy on your radio

Listening is actually one of the more power-intensive things a radio does, because it tends to be active more of the time than transmitting does. For many radios power consumption is the same whether transmitting or receiving.

Re: How does Google know where I am?

#95

Post by dragonwriter »

grkvlt wrote: post #83
dragonwriter wrote: post #63

Earlier quoted context omitted.

> Yes, that probably is a legal activity. However, someone could sue for a restraining order. A restraining order is issued for either actually illegal activity, or for activity whose legal status is in dispute, and which would irreparably negatively impact a party in the case in which it that status was in dispute, or for activity which might straddle the line of legality but which is related to a broader pattern of…

No, a restraining order is issued when someone is performing actions that, taken individually, are legal - recording a link between an SSID and a street address, knocking on an ex-girlfriends door to ask them to talk to you, photographing a child - but when carried out systematically, constitute a pattern of behaviour that is undesirable, and by virtue of the order becomes illegal. Sometimes the pattern itself is als…

> No, a restraining order is issued when someone is performing actions that, taken individually, are legal - recording a link between an SSID and a street address, knocking on an ex-girlfriends door to ask them to talk to you, photographing a child - but when carried out systematically, constitute a pattern of behaviour that is undesirable, and by virtue of the order becomes illegal.

The subset of restraining orders (sometimes called "protective" orders) you are thinking of are available when something illegal has been done, and relate to patterns of activity related to that illegal thing. For California, there are several kinds [0] of such orders:

(1) Domestic Violence Restraining Order: available if someone close to you in specific ways defined in law has abused you in specific ways defined in law as acts of domestic violence.

(2) Elder or Dependent Adult Abuse Restraining Order: available if you are elderly or disabled and have been a victim of certain kinds of abuse.

(3) Civil Harassment Restraining Order: available if you are being harassed or stalked, etc., by someone not close enough to be covered by a domestic violence restraining order.

(4) Workplace Violence Restraining Order: available to an employer to protect an employee that has been a victim of stalking, harassment, violence, or serious threats.

Now, yes, they sometimes cover acts which would not otherwise be illegal, but they actual require something illegal to have happened as their basis (a temporary restraining order can be issued on the claim that such a thing has occurred, and a permanent restraining order only after a hearing to determine that.)

[0] http://www.courts.ca.gov/1260.htm

Re: How does Google know where I am?

#96

Post by dogma1138 »

dogma1138 wrote: post #35
leot wrote: post #11

Earlier quoted context omitted.

Do you have a citation on phones using inertial navigation?

The technical term is usually sensor fusion and route prediction, this is how your phone knows that if it gets a weird echo from the GPS signal that you haven't jumped 150 meters forward under 1 second or help you navigate in doors etc. It is also used for indoor navigation, Google had quite a few talks about this this one is from Google I/O 2013 https://www.youtube.com/watch?v=oLOUXNEcAJk (click to https://youtu.be/…

I found the 2010 technical talk https://www.youtube.com/watch?v=C7JQ7Rpwn2k

And the 2nd 2013 talk https://youtu.be/Bte_GHuxUGc?t=400

Re: How does Google know where I am?

#97

Post by binoct »

dogma1138 wrote: post #48
binoct wrote: post #20

Earlier quoted context omitted.

I'd also be curious to see a reference for Orientation/heading from a phone's gyroscope/compass can be pretty reasonable, but most mems accelerometers are pretty much crap for dead reckoning use when loosely attached to a person. I could definitely see some interesting ideas with cell tower position data + heading + pedometer estimation getting merged, but I have a hard time believing that works in practice.

This isn't using a "pedometer" this is fusing the input from multiple sensors like gyro, accelerometer, magnetometer, barometer etc. as well as other location data (wifi/gps/cellular/beacons etc.) and extrapolating the location using a path prediction algorithm. Given a known starting point, or a known point in general this increases both the speed and accuracy of identifying your location considerably even outdoors.

I think we're starting from the same assumptions - my reference to pedometer meant the software-fused data from whatever on-board inertial/nav sensing was available, 6DOF IMU, compass, etc... In practice in consumer products I most often see this provided as "estimated distance" based on a learned or hard-coded model of what a single step looks like from the IMU (the pedometer part) + the output of GPS/cell/wifi localization.

I'm specifically curious about evidence for a commercial smartphone that can track you to room-level accuracy using only IMU + GPS. (Add in wifi or other RF triangulation and it's clearly a solved problem.) In practice with a cell-phone GPS receiver and IMU only, attached to a person it is a hard problem to track a path to within a few meters. Trying to use accelerometer data to get position information over more than fractions of a second in that situation is... tricky.

Re: How does Google know where I am?

#98

Post by sliverstorm »

Gracana wrote: post #86

Wifi mapping is the method by which google has no idea where I am. My roommate moved across the country and moved in with me, and android thinks I'm at his old house whenever I connect to his wifi router, even with GPS enabled, and even having installed OpenWRT and changed the ssid of the router. It's pretty maddening.

You can switch your phone to "Device Only", to use only the actual GPS chip.

Re: How does Google know where I am?

#100

Post by dogma1138 »

binoct wrote: post #97
dogma1138 wrote: post #48

Earlier quoted context omitted.

This isn't using a "pedometer" this is fusing the input from multiple sensors like gyro, accelerometer, magnetometer, barometer etc. as well as other location data (wifi/gps/cellular/beacons etc.) and extrapolating the location using a path prediction algorithm. Given a known starting point, or a known point in general this increases both the speed and accuracy of identifying your location considerably even outdoors.

I think we're starting from the same assumptions - my reference to pedometer meant the software-fused data from whatever on-board inertial/nav sensing was available, 6DOF IMU, compass, etc... In practice in consumer products I most often see this provided as "estimated distance" based on a learned or hard-coded model of what a single step looks like from the IMU (the pedometer part) + the output of GPS/cell/wifi loca…

This is what Google does, the GPS updates are actually pretty infrequent, especially if you specify low power mode, or they detect a slow activity and or you are indoors. Google's location API fuses all the sensors, they rely heavily on sensor data for indoor tracking and it's been getting pretty darn good since they've introduced it 2-3 years ago. I've linked a few google talks in this thread already, and you can read about the Fused Location API.
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