Unstuck in Time and Space: An Investigation into Location over WiFi.

I track my location with Google and my phone, because I lack sufficient paranoia. To the right is my June 30.

I swear that I didn't leave the Greater Lafayette area. I certainly didn't teleport to the southern suburbs of Indianapolis.

This happens to me all the time, and it has bugged me a lot. But, normally I've just looked and griped, rather than trying to work it out.

Today, however, I'm watching a compiler or two, so I have some time I can use to work this out.

The protocol is KML, and this is what it looks like:

That isn't all day's results, merely the point in time I jumped 67 miles to the southeast. I was going to try to use a KML-specific Perl module, but found that the ones I could find were more about generating it than parsing it, and it's XML, so I figured what the heck.

I had previous code to work out the distance between two points, so it was an easy case of parsing to find the jump:

Breaking it down, at 2015-06-30T13:13:05.103-07:00 I go 67 miles to Greenwood, and at 2015-06-30T13:53:31.467-07:00 I pop back.

Let me bring up an other map.

 I didn't have any mapping software going, and I was using wifi, so this data is location via wifi not GPS. I know, though, that the group that runs my servers has a weekly "coffee break" on Tuesdays, that I met with my admin there, and I walked around toward his office before goign back to mine. His building is off S. Grant St., and I walked next to Hawkins Hall, in front of Pao Hall, near the Forestry Building and down to my office in Whistler.

So, question is, how does location over WiFi work? I recall hearing that routers and access points report location, but I'm not sure of the protocols involved. I can imagine two possible scenarios that cause this.

First is that one of Purdue's routers is misreporting location, either in Forestry or Pao. This is possible; I have another issue that I haven't worked through yet where I leap instantly to the EE building, and it seems that's entirely based on location within my building.

The second scenario, one I'm taking more and more seriously, is that there's a replicated MAC address or something between the apartments across from Pao Hall. I say "or something" because MAC addresses should be unique. The thing that makes me suspect this is that it points me to a residential neighborhood south of Indy, and I could see that mistake happening with two residential routers or two experimental electronics projects.

I'm curious about how to test this, because I do want to know it has something to do with Purdue's networking gear before I complain. I'm also curious about how these things actually work. I could very much see me walking around, looking at Google Maps and tripping over things, then trying to dump my ARP tables or something.

How Can My Computer Know I'm At My Desk?

The problem is exactly as stated. I have my computer do certain alerting things, but unless I'm physically near, I don't it to do some of  'em. And it would be nice to be able to use it to enable certain security aspects, less "unlock when I show up" but rather "lock when I leave". But first, of course, we must have that mechanism.

So what are our choices?

• Motion Sensor - I like it. I used to have one in my den to control the light. It's neat. For work areas, I strongly suggest them for your lights, and have on this blog in the past. But you don't always have motion, especially when you've messed up line-of-sight or have a moment of stillness. So, it's a factor, but not the factor.
• Light Sensor - That won't tell me everything, but will tell us something, and that something is that the light switch is on at my desk. Not perfect, because often my coworkers turn the light on when I'm not yet there, but it's certainly better than nothing. 
• Location Sensing - My phone is the very definition of an Every Day Carry, and being a GPS-enabled Android which talks to Latitude, I can query Google to find out where I am. Except, where I am at work is in a subbasement, with no radio and no cellphone, so the location sensing defaults to a switch on the other side of campus, which hardly works. Maybe I should try it for "at home". 
• WiFi - If my phone is connected to my home network, my switch knows it and with a little coding, I can use it. Which is great, but when I'm at home, I often have WiFi off, and sometimes I use 4G (in the one corner of town where Sprint has 4G). Sometimes I don't though, which makes it a poor indicator at home. But it gets worse at work. My desktop is behind a firewall and my phone would be on the campus WiFi, so never the twain shall meet. I could write something that announces every 10 min or so that I'm on the campus network, should I ever get far enough into coding Android, but it isn't there yet.
• Bluetooth - This is the one I'm currently dreaming about. My dongle is Class 2, which means I have about 30 feet of range (and possibly less at the office). That's a nice range.

Without the addition of hardware I don't yet own, I'm thinking that the best solution is Bluetooth. I think that I could have fun making a dingus with Arduino that does motion sensing and light sensing (and maybe a thermometer) so I can get all sorts of data I can play with, but I can't play with that at work tomorrow.

Any thoughts I'm missing besides USB dongle and smart card you can think of?