N0QBH FreeTrak

For 16F628A PIC micro


This encoder will turn serial NMEA data from a GPS receiver into APRS format AX.25 data packets.

When interfaced with a ham radio transceiver, it allows you to track the location of the GPS on a map in real time.

FreeTrak can transmit either conventional packets or the mic-e compressed data format.

A unique aspect of this design - generates FSK tones with the PICs built in 4 bit voltage reference instead of a modem chip.

The built in configuration routine allows you to enter all it's parameters with any serial terminal program.

FreeTrak 2.02B Features

Buffered transmit handles low impedance mic inputs.

Sends either entire RMC sentence or mic-e compressed format.

Message bits can be set on the fly.

Busy channel detect feature.

Outputs packet radio AX.25 at 1200 baud to transmitter.

Configuration with any serial terminal program.

Open source software free for non commercial use.

Software tone generation - no modem IC needed.

Redesigned hardware interface runs on 7 mA current.

Click on schematic for larger view in PDF

FreeTrak 2.02B

Latest release of FreeTrak (2008).

Menu driven configuration. Example configuration at right.

Open source program for the 16F628A PIC.

For use with this new hardware design only.

Includes the dev_set utility for easy deviation adjustment.

Download includes: software, schematic and readme file.

Available built and tested from WB9JFR: e-mail him

Questions and inquiries can be sent to: ask Mike

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This page was updated 7-3-2010