Very, very early stages of a project right now.
Specs/contstraints include the following —
• GPS "tracker"
• Small size (may be a bit thicker than an iPhone, but not as long).
• Reports position over GSM/GPRS at minimum once per day.
• Battery life of (at minimum) 30 days.
Examples of similar existing technologies —http://staging.freightsecurity.net/products/sendumpt200
Good, but too large/long w/ batteryhttp://www.whelectronics.com/Data/AirLoom%20Specifications.pdf
Not enough battery life. Not sure why specs require 12V either?
My approach would be to either hack/mod one of above devices to meet my needs ("shrink" the Sendum, increase battery life on Air-Loom) or design my own.
I would kind of like to attempt my own design...just to say I did, and have more overall control.
For my own design, so far I have been playing with the following for prototyping purposes—
• Arduino UNO
• Adafruit Ultimate GPS logger shield http://www.adafruit.com/products/1272
• Adafruit accelerometer breakout (for possible motion activated GPS logging feature) http://www.adafruit.com/products/1120
My "plan" thus far is once I have all these things working together, I will (attempt to) design & build a single PCB to contain everything.
I do realize this is no trivial task.
The GPS shield has an SD card for data logging. Though the GPS device itself can hold substantial/sufficient amount of logged position data internally. So, that may simplify things....a little. Also, the GPS can "remember" single ephemeral data for three days to help acquire position more efficiently after being woken up. Nice.
Ideally, the device will be asleep most of the time to conserve battery. It would wake up once per day, and/or after some movement (triggered by accelerometer...suggesting it may soon be outside, thus having a better chance if getting location fix, and possibly wireless signal to send position back to server.
I have the GPS spitting out parsed NMEA sentences already. And I'm figuring out how to get it to do what else I need.
For any specific questions I have...
• Best way to have Arduino sleep & wake when I need it to? How much power could I reasonably save doing this & maintaining the functionality I require?
• Suggestions/advice on calculating my battery requirements? Ways to keep that at a minimum?
• Suggestions on "best" GSM/GPRS device to use? - Efficient, low power, reliable...r just easiest to obtain & find support for it?
• Advice on where else to hunt for god information? — I could, and have been, Googling the heck out of all these things. But, I'm hoping to leverage some of your experience to help me narrow down the results to reliable & helpful resources.
• Anything I didn't mention, but need to consider at this time.
I know this is all still very vague, but I hope to get into more specifics soon.
And, since we always ask the OPs....this is part personal curiosity - to see if I can do it - and part potentially real-world use for un-named third party. They have specified a need/desire for this, and I'd like to try and help make it happen.
Any advice, suggestions, tips, warnings, personal experience, or otherwise useful input or questions are welcome & appreciated!