In REHAB1, we are using the Lassen IQ 12 channel GPS module for our onboard GPS receiver. It works reasonably well, is able to provide NMEA formatted longitude/latitude information as well as altitude. It has 2 serial output channels, of which we are using both. One channel feeds directly to the transmitter through the MAX3232 chip for leveling. The other channel is fed into the CPU board for local tracking.

There are 2 power rails on the GPS board, the 9V rail which is fed to the transmitter, and a 3V rail, regulated by the PTH08080WAZ buck converter. There is also an onboard coin cell battery to keep gps tracking information saved in the Lassen gps module.