APRS

Lots of info

http://info.aprs.net/

USBlink http://www.g4ilo.com/usblink.html USB sound card + VOX interface to PTT switch + HT

Some notes on available hardware

Kenwood TH-D74A handheld with built in GPS and APRS
Kenwood TM-D710A mobile with a UBlox GPS, installed in Alba.
Byonics Tinytrak 4
Byonics MT8000

Other 2M HTs including two ICOM F11s which have no external power connectors (battery only) and a Kenwood TH-F6A

Breaking this all down I need a receiver to work as an iGate with a Pi 3, and a transmitter to implement a Digipeater.

Step one is the iGate as a data sink since I can already use the Kenwoods as sources. There is no iGate close to my house. So that is my first need.

iGate on a Pi

Two common approaches (1) SDR (2) sound card + HT. I have a cheap USB sound card and a RTL-SDR on order now. The RTL-SDR appeals to me the most.

Eventually, if I end up using one radio for receive and one for transmit, how do I isolate them? One way is two antennas, and pull the receiver input to ground when transmitting. http://www.ok1rr.com/index.php/technical-topics/39-yet-another-front-end-saver

Direwolf - popular.

Xastir - this is a desktop app so I am not looking at it.

Argent Data Systems

Products for amateur radio including APRS applications

http://www.argentdata.com/

2m Transmitter MX146 from SRB -- This is a 500 mW transmitter, $70

OpenTracker+ is open source / open hardware and uses a Motorola MCU.

Tracker2

These are controllers, connects a data stream (eg weather or gps) to a Kantronics TNC.

They now have a Tracker2 with a 5 watt 2m radio now. T2-301 $229

Byonics

http://www.byonics.com/

Maker of TinyTrak controllers and MicroTrak transmitters

Purchased way back in 20 Aug 2010 and tossed into a "future projects" box. I got a TinyTrak4 controller kit and a MicroTrak MT8000 8 watt transmitter.

2013-Sep-03 I am thinking of using the TinyTrak+MT8000 with a Garmin GPSmap as the NMEA data source, with the Garmin Power/NMEA cable. Then I can carry it on a bicycle.