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Location-based alarms


I just had a cool idea, though it may not be original (and it may not be feasible with current cell phone technology).

My Treo, like any PDA or smartphone, currently lets me create an item on its calendar and specify that it should give me a reminder alarm a certain number of minutes (or hours) ahead of time.

Which is fine, but sometimes what I really want is for it to remind me to do something when I arrive somewhere. If I leave work and start to head home and then realize there's something I want to remember to do as soon as I get home, I can certainly pick a time n minutes in the future and create a calendar item with an alarm on it for that time; but it would be more elegant to be able to say "When I get home, regardless of how long it takes me to get there, remind me to take the trash out" (or whatever).

This would require my Treo to know my location. I'm not sure what the state of the art is for integrating GPS into cell phones. But I keep thinking that in a few years, GPS will be a standard part of any cell phone, and then it seems like it would be fairly straightforward to write an app that says "When you get within n meters of location x, set off the reminder alarm."

Do GPS units already have that capability?


The technology exists today, and it's called e911. It essentially relies on triangulation between multiple cell towers, and only works in areas of a certain cell density. However, e911 is very difficult to implement due to stringent privacy regulations -- the only classes of service for which it is approved are emergency services.

(At work I specced an app which would recognize when you entered a non-home cell service area and push you weather and travel info via SMS, with a link for lodging, local news, etc. Couldn't build it though, not yet.)

There was a paper on this type of phone messaging and alarm system presented at Chi this year - actually, people are working on both alarms and messages the user can set themselves, and enabling other people in your social circle to know your list of locations and send you location-based messages (so that I can send my husband a reminder of what to buy at the store that will get to him *at the store* instead of while he's at the office, for instance).

See "Because I carry my cell phone anyway: functional location-based reminder applications"
and "User experiences on combining location sensitive mobile phone applications and multimedia messaging"

Jay: I didn't mention e911 because I thought the emphasis there was on letting the 911 operator know where you are, which does open up privacy issues. But if the phone knows where you are and lets you take action based on location, that seems to me to not be so much of a privacy issue; the location data never leaves the phone.

Cool idea re giving local info when you enter a different area!

Anne: Nifty! Thanks much for the info and links--the first of those articles sounds like (an enhanced version of) exactly what I was thinking of, and the second (if I understood it right) sounds a lot like what Jay's talking about. And, yeah, the enhancement of letting other people send you location-based messages is way cool. (That part sounds a little like Dodgeball, only with less user action required.) Glad to see people working on this stuff.

Actually, I think this is already implemented, in an annoying rather than cool way. As we were driving to Reunion, I activated Steve's phone in order to call work. Within seconds, a call beeped in, which I fortunately didn't interrupt my call to check. Checking messages afterwards, we found a recorded advertisement for a NYC restaurant. So, our best guess is that there was a program out there somewhere which, when noting a cell phone (perhaps specifically an out-of-area one) activated in the vicinity of the restaurant, would automatically call it with an advertisement. Really annoying, even more so when we have to pay for incoming calls.

Yes, I thought about this last year and implemented is as a course project. You can find the project report here - http://www-static.cc.gatech.edu/~anandm/projects/spatialAlarms/SpatialAlarms.pdf

Let me know if you would need the sources.

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