Please help me understand spimes.
September 16, 2010 6:41 PM   Subscribe

I really thought that small, cheap location aware devices existed and could be purchased but I can't find any. Do they not exist yet or am I using the wrong search terms?

I just spent the last two hours in GPS/RFID/mobile/ubi-*/blah blah blah land and my head is spinning. Are spimes still theoretical? Are they a reality but still very expensive? Forgive my naivete but I'm totally lost (heh).

I want to experiment with tracking an object across my city. I thought I'd be able to buy something fairly ubiquitous (like an RFID tag but that emits geo-coordinates) to play around with, but the closest I can find are expensive collars for lost dogs and various programs that hack pay-as-you-go mobile phones.

Have I oversimplified the technology/power/access requirements for such a thing?
posted by 10ch to Technology (11 answers total) 5 users marked this as a favorite
Yes, you're oversimplifying.

RFID is a short-range technology that just chirps "Hey, I'm the tag with ID number 33920232349723408!" when you bounce the right signal off of it. Without a lot of software, transceivers placed on every lightpole in town, and other information, it's essentially useless for your purposes. An RFID tag doesn't have any idea what location is, let alone where you can find it.

GPS does not transmit! It only receives. So, the GPS module may know where it is, but it has absolutely no way of sending that information to anybody else.

If you want remote GPS tracking, you need a cellular module to transmit data from the GPS module.

You'll also need some electrical engineering done. And some software written. The whole package should run you about $150 in hardware, and be about the size of a pack of cigarettes. With engineering costs as well, you're probably talking about $1000 at least. Hacking a PAYG phone is probably a much cheaper option.
posted by Netzapper at 6:52 PM on September 16, 2010

Oh, and honestly, you shouldn't be discouraged; you should consider PAYG phones as your answer. They're exactly what you want.

You load a little bit of software on the phone that asks the GPS where it is, and then sends that to you as an email or text message or talks with a server you're running. Then, you can analyze the results in any sort of mapping software you like (Google Earth, for instance, would be great for this).

Hell, find a PAYG phone that supports Google Latitude, and the whole project is already done for you.
posted by Netzapper at 6:57 PM on September 16, 2010

Response by poster: Thank you for explaining each of those acronyms in such a short and direct way, Netzapper.

As for the PAYG phone option, I'm only discouraged in as much as I'd like there to be lots of them and so it doesn't scale as well as I'd like. Still, good to know that I can prototype the idea easily.

posted by 10ch at 7:10 PM on September 16, 2010

You might be able to use a Spot satellite tracker. It gets its location via GPS signal and then transmits the coordinates to a satellite (so it works just about anywhere in the world, unlike cell phones). It can be set to transmit its current location every ten minutes, and the batteries last a very long time. By default the location data just ends up on Spot's web site, but it can also be hooked into Yahoo! FireEagle which provides an API that lets you access its data however you like. The device costs around $150 plus there's a yearly fee.
posted by Emanuel at 7:15 PM on September 16, 2010

I just heard Chris Csikszentmihalyi talk about one of his colleagues at MIT Center for Future Civic Media who is involved with a grassroots mapping project that started in art b/c large tracts of Lima Peru were not available on google maps. Now, with kits that are are kite-mounted, costing roughly $00, they have been mapping the gulf oil spill. Dunno if these have any application for what you're looking for, but there might be some intersection here.
posted by beelzbubba at 7:18 PM on September 16, 2010

You might want to look at the Trash Track project from the Sentient City program. They used beacons of some sort to track trash as it moved around Seattle, I think.
posted by Admiral Haddock at 7:28 PM on September 16, 2010

As for the PAYG phone option, I'm only discouraged in as much as I'd like there to be lots of them and so it doesn't scale as well as I'd like. Still, good to know that I can prototype the idea easily.

Can you elaborate on that?

If this is going to have a revenue stream associated with it, then you can have these manufactured and reap the economies of scale. I think you could get your per-unit costs down very low. Like, $40-50 per unit easily.

If this is for your own personal amusement, then I don't think you're going to find anything under $100 per unit. I just looked at the Spot a couple weeks ago at EMS (for ~$150), but it requires a $100 per-unit yearly subscription.

The killer here is really the transmission requirement I'm seeing in your discussion of dog-tracking collars. If you're content not to know where an object is, but rather where it's been then we can get the cost down to under $40 apiece at the prototype scale. You get one of the cheap GPS modules I linked to above, and hook it up to any random microcontroller that can talk to a flash memory chip. Save the entries from GPS onto the flash, and read it out on your computer when you recover the bug.

The only issue, at this point, becomes the antenna for the GPS. Even the trunk of a car, or a sturdy oak tree, will block GPS signals.
posted by Netzapper at 7:45 PM on September 16, 2010

You don't say much about "tracking an object," but this will typically be at least one order of magnitude simpler and cheaper if you get the thing back afterward. You can get any number of running/cycling GPS modules/watches that will record their entire route, after which you download the data into your computer. The other way around? Cellphone plus GPS location plus SMS as often as possible.
posted by rhizome at 11:06 PM on September 16, 2010

Response by poster: Netzapper,

The idea is to experiment with trust. Teams racing across the city (slowly racing, like over a month where the object they move has to stay put for a certain amount of time) can cheat (steal another's object and move it somewhere else), but all teams are always aware of where their objects are. So if yours has been moved, you know where it is.

I'd need a tracker for every team, there could be dozens.


If I can't swing real-time location data due to cost, there may be a way that participants "park" their objects in a usb hub at each destination. If I go this route, do you have any recommendations for what to use? Is this referred to as a logger?

Admiral Haddock,

That project is awesome -- hadn't heard of it and that's exactly what I need. I dunno how attainable the tech is, but I'll follow up with the folks at MIT to check.

Thanks y'all. This is super helpful.
posted by 10ch at 6:04 AM on September 17, 2010

This brought to mind a Hitchhikers experiment from a few years ago. Life-size cutouts were left by the road, with notes on their backs with their destinations in mind. They had tracking systems, using cheap pre-paid mobile phones & car batteries to keep them charged for a full month - the built-in batteries only last a day or two, which is fine if you have people "park" them regularly. They used the Motorola i415, a few of which are listed on eBay's "Buy It Now" for $13.

Your price constraints aren't clear to me.
posted by Pronoiac at 2:15 PM on September 20, 2010

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