Build Your Own GPS/APRS Tracker – FreeTrack 2.02

FreeTrack 2.02 – GPS to APRS Tracking Encoder

“This encoder will turn serial NMEA data from a GPS receiver into APRS format AX.25 data packets.
By using this hardware with a 2 meter ham radio and the freely available APRS computer software, you can track the location of the GPS on a map in real time. Latest release now supports the mic-e compressed data format for much smaller packets.

The unique aspect of the design is in how it creates frequency shift keying (FSK) tones with the PICs built in 4 bit voltage reference instead of a modem chip.
FreeTrak's built in configuration routines allow you to enter all it's parameters with any serial terminal program.”

Getting APRS working with my Kenwood D7A

I struggled to get APRS working with my Kenwood TH-D7A/G. The following things were done. I haven’t confirmed all of them were necessary…

On the GPS… (Magellan Meridian GPS)

    • Set speed to 4800Bps from GPS to radio.

On the Radio…

    • Made sure that GPS was sending information to the radio by using the POS button
    • Made sure that the radio was set for waypoints to be “….MGN” to work with the Magellan Meridian GPS I am borrowing.
    • Set Band A freqency to 144.390
    • Set Band A as the data band
    • Set Band A offset to “0.00” (default was .600)
    • Set CTCSS tone to ON for Band A (This is to squelch all the “modem” noise.)
    • Set My Callsign
    • Set My Icon
    • Set Data TX as AUTO
    • Set TX Interval to 2min
    • Set POS LIMIT to 150mi (help eliminate information I don’t care about)
    • *IMPORTANT* Set Packet Path
      From: RELAY,WIDE
      To: WIDE1-1,WIDE2-1
    • Pressed TNC so that ONLY TNC appeared (No “packet”).
    • Last but not least… pressed the “BCON” button.

Listen Before Speaking

I’ve been told that many people misunderstand the proper etiquette behind ham radio. Many people think that it is a hobby which involves a lot of talking. In reality, I’m being taught that it is more about listening. This makes a lot of sense, and is indicative of the culture I’ve found in ham radio.

As a new ham licensee, I obviously want to learn the proper procedures and protocols… as well as follow the above suggestion. I wanted to find a way to be able to quietly listen to Kenwood TH-D7A/G without annoying my co-workers. I found a great adapter to go from the 3/32″ mono phone jack on the Kenwood, to 1/8″ stereo headphone (RadioShack PN# 274-381). What I really like about the adapter is that it takes the mono and makes it stereo… so I can listen with either side of the headphones… or both.

This should help me learn more about the hobby, and discover which repeaters match my interests!