DIY GPS Tracker Rev 3

This design is now outdated, because the one and only prototype is now laying out in the Mojave desert somewhere, not transmitting its location. Work has begun on a revision 4 of the tracker which should be more reliable, expect a prototype sometime in September '08.

In any case, for some history about how the project got started, and what happened to the rev1 and rev2 trackers, see these forum posts. Hopefully I can get around to making formal pages for them in the near future...
GPS Tracker Rev1
GPS Tracker Rev2
GPS Tacker Rev3 (this one)
Krazed III (the rocket it will fly in)

After the unfortunate death of the rev2 version of the tracker, I decided that the next revision would have a microprocessor on board so that I could fire charges remotely (chicken switch). That then lead to having a few extra sensors, and then I needed some memory to store all of the extra data in, and a new power supply to keep everything running off a single LiPo cell, and I ended up with the following list of requirements:

• Fit in a 38mm tube
• Have at least 2 mile range, and not require a HAM license
• Be able to remotely fire 3 charges (main chute, drogue chute, tracking smoke, etc) while in flight
• Send GPS data back to the pad at least once per second (to find the rocket)
• Run off a single LiPo cell
• Store all data taken during flight in in nonvolatile memory
• Store altitude and acceleration data at 100samples/sec
• Be able to be expanded easily

• lassen IQ GPS
• Ultra Compact Antenna
• XT09-SI 900MHz transciever
• 900MHz Halfwave Dipole Antenna
• max1763 1.5A 3.3-5v boost converter
• PIC18f2550 Micrrprocessor
• MMA2002G +/-50G accelerometer
• LIS3LV02DQ +/-6.5G 3axis accelerometer
• MPXA4115 0-15PSI pressure transducer
• MCP3221 12bit A/D converter (for altimeter)
• AT45DB321C 32Mbit FLASH

And then drew up a schematic and did a board layout: (note, there are some errors in these, for reference only)

And sent the artwork out to batchPCB.com

and populated the board:

Results:
I flew it in Krazed III on 10/13/07, on a I287 2 times, and on a Hypertek J317 once on 4/6/08. Unfortunately, the code to use the flash memory wasn't working, so the only data I have is the 1hz location/altitude/acceleration data. See Krazed III's page for the data.

Code:
I am currently working on the code, and do not have anything flight worthy.
If you would like the alpha code, email me.

Licensing:
I am offering the design and code under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.
Which essentially states that you can do whatever you want with it, so long as you

• attribute me
• share your code under a similar license
• do not sell it

questions? comments? Want to help? email me gps@krazerlasers.com