Key features are low power consumption, remote sysop functionality, multiple GPS sentences, and . Another excellent choice is the PicoPacket . This unit features a small size and several useful options for mobile and portable use. These include a battery pack, built in GPS, and second serial port. This latter option deserves a little explanation.
Most laptops only have a single serial port.
The cheapest way is to buy or build a hardware single port interface . The disadvantage is rather than a continuous stream of GPS data, the computer only sees a position at a user-settable interval. PacComm has a far more elegant solution. The PicoPacket senses when a computer is attached, and turns off the stand-alone mode, letting the computer control transmission. Remove or turn off the computer, and the TNC once again goes into stand-alone mode.