A wireless interface for your APRS system

The latest generation of PDAs, PocketPCs and Smartphones are well-suited to running APRS programs such as AGWTrackerPocket and APRS/CE.

These APRS programs can connect to one of the APRS internet servers, using a WiFi, 3G or GPRS internet connection, allowing you to have an APRS facility in your pocket!

However, the "proper" way to use APRS is via radio, but these tiny mobile devices don't have RS-232 ports, so how can they be connected to your existing TNC and radio?
Well, most of them do have Bluetooth built-in, so can this be used instead, to provide a wireless interface to the TNC and radio?

Happily, it's easy to obtain an adaptor to convert your TNC's COM port into a Bluetooth "slave" device.

The picture shows my Tracker2 in KISS mode at 4800 baud, connected to the Bluetooth adaptor.
The handheld terminal runs AGWPacketEnginePocket, which translates the packets between the Bluetooth port and the AGWTrackerPocket program (note that versions of PacketEnginePocket before October 2008 did not work under WindowsMobile5).

I can now use all the facilities of APRS (including tracking and messaging) from anywhere within range of the Bluetooth link, which is handy in the house, or even when operating outside, close to my car.
Note that the Tracker2 can also operate as an independent digipeater whilst in KISS mode.

Once your Tracker is fitted with a Bluetooth adaptor, this can be used to communicate with a wireless GPS receiver, to pick up the NMEA data stream.
The Bluetooth adaptor should now be configured to operate in "master" mode, with the GPS receiver as the "slave". The GPS receiver may then be positioned for optimum satellite reception, no longer limited to being beside the TNC and radio.

Note that some of the newer Bluetooth GPS units use very fast serial port rates (e.g. 115200 baud) which may be too fast for the Tracker's data buffers, and so the NMEA data won't be correctly decoded and the Tracker won't send its position correctly. The older 4800 baud GPS units should be OK though.

The Bluetooth-enabled TNC can also communicate with any suitable PC (either with integral Bluetooth, or using a plug-in dongle). The new "netbook" mini-laptop PCs are ideal for this, as they will run the "full-size" APRS programs such as UIView32, AGWTracker or Xastir.

Since the PC is also fitted with WiFi, it can even be IGate-ing as it is carried around, so long as it's in range of an access-point.

I've also managed to use the Bluetooth facility in my Asus eePC to connect simultaneously to my Bluetooth-enabled TNC and Bluetooth GPS receiver, and running UIView32 with data from both devices.

And if I use the AGW Packet Engine to interface to the COM port, it then puts all the APRS data onto an internal TCPIP stream within the PC, so that I can now run both UIView and RadioMobile at once!