I have a university project (with two other students) to make a somewhat-portable GPS tracking device. The smaller the better. My idea is to have an Arduino chip with a GPS chip, and then a GPRS attachment which would receive a text message asking for a GPS location, then turn on the GPS chip (need to save power), get the data, turn off the GPS chip, and send the data back as a text message in the standard NMEA format, which I'd then decode on an android app and put onto Google Maps. I've not used Arduino before but I'm very competent at programming, especially with C, and there are so many helpful tutorials around that I'll be able to cope fine, and as I'm at university I can just ask a lecturer for help if I do struggle, likewise with small hardware problems.
For the hardware, I think I need the following: An Arduino chip, a GPS chip, a GPRS device, two antennae (one for GPRS, one for GPS), and a power source.
This looks great as a somewhat all-in-one solution: http://www.cooking-hacks.com/index.php/arduino-mobile-navigator-pack-124.html with the following antennae for GPRS and GPS: http://www.cooking-hacks.com/index.php/internal-gprs-gsm-antenna.html http://www.cooking-hacks.com/index.php/internal-gps-antenna.html
The GPS tutorials I've been looking at are the following: http://arduino.cc/playground/Tutorials/GPS http://www.cooking-hacks.com/index.php/documentation/tutorials/arduino-gps
The GPRS tutorial I've been looking at is the following: http://www.libelium.com/squidbee/index.php?title=New_GPRS_module_for_Arduino_(Hilo_-_Sagem)
I feel fairly confident but have a few questions: 1) Would the GPS device be constantly polling for a new location, or does it only do it upon user request? I only want it to check for a location upon receiving an SMS to save power. If it powers on when I request a location, that's fine. If not, how would I turn it off?
2) What power source would I need? A thread on Cooking Hacks link here (which provides the GPRS chip) suggests that this device would provide enough power. However, it's very expensive. What would you suggest as a power source? Remember, small is key! I see a mention in the GPRS tutorial about using a capacitor if the amps are too low. Would you suggest that? Again, I would love to use a small power supply (Ideally I'd use a regular 9V battery - would that work with a capacitor to provide the power required?)
3) Do you have any suggestions or tips? Is there a cheaper way to do this? We have a budget and these components alone take us a little over the budget, so any way to make it cheaper would be welcome.