Last updated: 20140413

Automatic Packet/Position Reporting System was developed by Bob Bruninga, WB4APR, for tracking and digital communications with mobile GPS equipped stations with a two-way radio (check out the APRS Wiki).

Where am I? (work most likely)

An Introduction to APRS

I was asked to do an APRS introduction at the 2009 TAPR DCC. So I updated the previous slidesets and it is available here ( about 2.7MB pdf).

I also wrote an article (An Introduction to APRS) for the IRTS's "Echo Ireland" newsletter in an attempt to make some of the ideas in the slides a bit clearer. A PDF of the article is available here, and a further article on some of the more advanced features is available here

Before try anything on APRS, please read this first. If you are having trouble either having your packets decoded or decoding someone elses packets.

Some good places to start gathering information are WB4APR's homepage at, the APRS Wiki, AJ3U's tips on using the TM-D700, and OH7LZB's Google map based tracking. Have a look at Stephen, WA8MLF's page on HF APRS.

Have you read it yet?

APRS Voice Alert

First, I suggest you have a read of WB4APRs Voice Alert page. Basically it's a method to utilise 144.800 to automatically alert you to the fact that another mobile is in simplex range. The rules are simple and should be obvious to anyone who thinks about how the system works:

Kenwood TM-D710 users, check your user manuals on section APRS-13. There's also a section on Voice Alert.

Note: If you don't have a radio like the Kenwood D7/D700/D710 (capable of putting Tx/Rx CTCSS code squelch on APRS packets), you can still utilize the Voice Alert concept. Simply add the APRS frequency (144.800 MHz in Europe) with 136.5t CTCSS Tx/Rx frequency to your list of scan channels and then you will only hear any APRS packets sent with the same CTCSS tone frequency. Naturally, in this case you won't be able to decode the APRS packets, but you will know that someone is within range of having a simplex QSO.

Simply invite the other party to a 2m simplex channel as described in WB4APR's instructions. Remember to Tx with the same CTCSS code, otherwise the other party's squelch will not open.

Hint: As WB4APR mentioned in his instructions, the fact you are transmitting APRS packets with a CTCSS tone means you are there to answer Voice Alerts. If you want to transmit APRS packets when away from the rig then do so, but without the CTCSS tone. An easy way to do this is to utilize two memory channels and switch between them as necessary:

At a recent AREN event I used it to call Francis, EI5GOB. I was out of range of the SIRN repeater system, I heard a Voice Alert packet, looked at the display, spotted it was Francis, EI5GOB and quickly passed a message to him, we also agreed a simplex channel to operate on until we both got back in range of the repeater system.

APRS In Ireland

We still have a 'fledgeling' APRS infrastructure here in Ireland, mostly concentrated in the South, South East and East of the country, with some activity in Dublin (EI7BFB Digi and I-Gate), Galway, Limerick, Cork and Tipperary.

At the moment the main part of the infrastructure is maintained by the South Eastern Amateur Radio Group and it consists of the nodes:

Also, there are I-Gates operational at EI4GTB, EI3RCW (Waterford Institute of Technology), and sometimes my own home station. EI8JA (SEARG's equipment manager) and I encourage the use of the following UI-PATHS in Ireland: At the moment, that is enough to reach an I-gate from pretty much anywhere in the network, which consists of a mixture of TNC's running UI-DIGI and Argent Data Systems Tracker2 (both the T2-135 and OT2 versions)

APRS Internet Servers

The APRS-IS is an Internet-based backbone network which interconnects APRS radio networks. The core network consists of three (two now?) first-tier servers and numerous second-tier servers, providing a unified worldwide APRS stream to connected clients.

Purely for practical reasons (aggregation), not political ones, I maintain a Tier 2 server, which allows Irish APRS Internet Clients a common aggregation point.

The easiest way to gain access would be to configure your APRS client to connect to with the port set to 14579

Irish Maps

Xastir now supports downloading OpenStreetMap tiles on the fly, so the rest of this section may no longer be relevant.

Here are some maps made available courtsey of Tim, EI8IC. I added the .inf and .geo files in order that Xastir and UI-VIEW can use them.

I have also generated a (9MB) map of the entire country, with a geo and inf, and the South East (also 9MB) with a geo and inf files.


Here are some .dbfawk files, for Xastir. They are a work-in-progress. A company in Germany called GEOFABRIK have converted OpenStreetMap to shapefile format and makes them available here (thanks to Carl, VK1KCM for the assistance and also the heads up).

APRS Hardware

I really like the Tracker2, as it is tidy, (the prototypes were relatively easy to construct) and is very flexible being usable as a tracker, digipeater and KISS tnc similtaneously. AREN has used APRS as a tactical communications tool on several events both in the hills and on the roads (Sean Kelly Tour Mobile, I use a Kenwood TM-D710E (what a great radio!) along with my venerable Garmin GPS V