Last updated 2020-05-17

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 Bob's APRS page, but mind you don't get lost!).

An Introduction to APRS

In 2009, at the TAPR Digital Communications Conference, I was asked to do an introduction to APRS. I based my presentation on one from John Beadles, N5OOM, So I updated the his slidesets and it is available here (about 2.7MB pdf). At the suggestion of John Langner, WB2OSZ, I updated it again in 2020 and it is available here (about 8.6MB pdf).

In 2005 I 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. While updating the slides above I updated the article also. The updated version of this is here.

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

Some places to start gathering information are WB4APR's homepage at aprs.org (note however it is a bit of a jungle), and aprs.fi 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 136.5 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:

Recently I used it to call Francis, EI9KT. I was out of range of the Southrn Ireland Repeater Network, I heard a Voice Alert packet, looked at the display, spotted it was Francis, EI9KT 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, Cavan, Galway, Cork and Tipperary.

At the moment the main part of the infrastructure is maintained by the Southern Ireland Repeater Group and it consists of the nodes:

Others include: EI8JA (SIRG 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. Both products have since been superceeded)

APRS Internet Servers

The APRS-IS is an Internet-based backbone network which interconnects APRS radio networks. The core network consists of several 'core' 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 ireland.aprs2.net, 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 ireland.aprs2.net with the port set to 14580

OpenStreetMap

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 Argentdata products. Some are usable as a tracker, digipeater and KISS tnc similtaneously.

At public service events I have used APRS as a tactical communications tool both in the hills and on the roads for events such as the now defunct Sean Kelly Tour of Waterford. This event had approximately 5000 cyclists in three separate events spread out over 1600㎢. The Byonics MicroTrak AIO proved very useful during this and other events.

Mobile, I use a Kenwood TM-D710GE, and I also own a Kenwood TH-D72.