find my art via GPS

August 5, 2012 9:58 AM

Hi mefites, I'm researching for an art project that needs a robust GPS unit they can put in a project that will be mobile around a few mile area. The GPS needs to be fairly robust in terms of ability to withstand shakes and jounces, being upside down or turned and twisted. We're not talking bouncing it like a basketball but rather the unit will be in a larger package moving about and being shifted around a lot. We need to be able to find the unit via GPS for a 24 hours run time. Actually, the run time needs to be at least 12 hours but using 24 hours as a way to give some leeway. When I say GPS, really it's a GPS plus the ability to signal someone where it is located. It seems to me like a cell phone would qualify for this. What are some of the options? Robust, power miser, and locatable in a 5 mile wide area. That's about it. Thanks for any tips on this.
posted by diode to technology (9 answers total)

A Spot tracker sounds like it would work. It can run for a week or more on a pair of lithium AAs, can upload its position every five minutes via satellite (so no need for cellular coverage), and is very sturdy and waterproof.
posted by Emanuel at 10:08 AM on August 5, 2012

Yeah, a Spot was my first thought to. Position is actually every 10 minutes, and the website is awful (and occasionally down), but mostly it works well. The upside down part may or may not be a problem; I don't know whether the transmission antenna works well pointed the wrong way.

Your requirements list sounds like what the various amateur space balloon hackers need. May be worth looking into that community to see what they use.

I'd rule out phones; 12 hours is a lot of battery life. If you're in a region with good cellular though maybe it's possible to manage with an external power source. There are zillions of iPhone apps that can do what you ask.
posted by Nelson at 10:44 AM on August 5, 2012

Woohoo! Great reply. Thanks. Excellent start. Kudos and appreciation.
posted by diode at 10:53 AM on August 5, 2012

I've got and have used a Spot, and love it, but it has some failings.

Primary amongst them is that, in the interests of preserving battery life, the satellite transmitter is exceedingly weak. When it says it needs an unobstructed view of the sky, it means it. I've gotten reasonable transmission success through cordura nylon, but the signal appears to be utterly attenuated by the human head (I put mine in my sport motorcycle's tank bag, and when I'm leaned over the tank for fast turns in long sections of twisties, I get frequent misses). Additionally, I've heard from other users that it really must be pointed up (or nearly up) for reliable transmission. If it's going to be in a box that may get inverted, it may not work well.

If you're amenable to DIY, there are some good bread crumbs on hobbyist forums. The real key you want, though, is GSM transmission, in my opinion. That way, you can get a beacon anywhere there's a GSM signal, which is nearly everywhere. And if the Spot's form factor is acceptable, that's enough battery life for weeks.
posted by TheNewWazoo at 1:30 PM on August 5, 2012

Here is what appears via Google results to be the gold standard for hackable/repurposable GSM+GPS trackers. With the addition of four of these batteries wired in parallel, you should average about 15 hours of battery life. If you're savvy enough to do some programming, I suspect you could get that number down by reducing transmission frequency, but I haven't really looked into it.
posted by TheNewWazoo at 1:40 PM on August 5, 2012

If you have a ham radio friend, another possibility is an APRS setup. Here's an example installable tracker. This will be much more robust than SPOT, but requires an amateur radio license to operate and some DIY work to set up.
posted by Nelson at 4:10 PM on August 5, 2012

To clarify, you need this to be live, and not something where the device can record its position and you can later re-play those coordinates ?
posted by k5.user at 7:34 AM on August 6, 2012

To end the thread, the team researching this found a dog collar for hunting dogs that is ideal. Robust, relatively inexpensive for what you get, and can be tracked for miles. Run time is 12-24 hours depending on how long the signal updates.
posted by diode at 8:19 PM on August 6, 2012

Would you mind disclosing the actual dog collar, for future readers? Something like the Garmin DC-40 maybe? It uses VHF to transmit position to a receiver up to 9 miles away. A bit pricy: $600 retail for the transmitter/receiver pair. But cool product, I had no idea it existed.
posted by Nelson at 7:48 AM on August 7, 2012