APRS – A beginners guide.

Before we start let me tell you a tale, there have been many told before, many since, but the most famous being the charge of the light brigade. But that is not where the story for us starts.

WWII, solders are given orders to enter a city, and they are given maps and targets (given operational names) In these days the Army had basic comms and had to rely on someone who could a) read a map and b) someone who could work the radio. Now a lot of these units where successful in doing their jobs, of getting from a to b without incident, however when a unit got attacked, they had to rely on both the navigator and the comms person to report the right location, if not bombs would rain down on the wrong location, and kill possibly the people they where intended to save.

This was not ideal, the officers and commanders needed to know where every unit was…

Pause for some time… and then we discover; APRS

What is APRS

APRS was designed to use packet radio to deliver tactical information such as location, altitude, a digital ID*, weather and other information. Many systems have incorporated APRS into there subsystems like TETRA used by the Police and Ambulance services, like the monitoring and tracking for the Post office and other courier companies that allow you to track your parcels.

But in the beginning it was for military purposes being the brainchild of Bob Bruninga, WB4APR, a senior research engineer at the United States Naval Academy it later became popular in Amateur Radio, where a lot more of its development has taken place.

APRS stands for Automatic Packet Reporting System not as commonly believed Automatic Positioning Reporting system. APRS uses a system of un-numbered packets being relayed between other stations, until it the packets (being duplicated and retransmitted by other stations (nodes)) finally get to a Gateway otherwise knows as an iGate, this is the link between the radio, and the internet. Once the iGate has relayed this information it becomes part of the APRS backbone available at many sources. The one I use is APRS FI although many others are available.

APRS in Europe uses 144.800MHz and 144.390MHz in the USA. Likewise High Frequency is also used, allowing the many HF stations out there to act as gateways between HF and VHF creating the potential for a worldwide radio-based network (now established). APRS allows information of tactical nature but it also allows for a messaging service, which later on was developed for mobile phones and has become SMS messaging. With APRS the issue is that although messages can be sent they can not be verified until the other operator responds on air to say its received.

What generally transmits?

  • Beacons
  • Repeaters
  • APRS enabled Radios
  • Ships
  • Weather Stations
  • Smartphones (with GPS) (Android, Windows and iPhone)

APRS transmission from my Weather Station at the QTH


APRS showing GB3AY repeater, MM0ZIF WX and non amateur DW4018 wx, as well as Ships the Isle of Arran and Loch Shira

APRS uses GPS location information (Lon/Lat) for placement on a map of your data, I use a mobile phone and my QTH has a WX station, here is a screenshot of the data.

The picture to the left shows the Repeater GB3AY (pictured as a tower and antenna) and 2 WX stations one being MM0ZIF and the other being Non amateur station DW4018 as well as to the top left the ship/ ocean ready boat Loch Shira and to the bottom left the Ferry Isle of Arran.

All these different images show you different information flowing back to a iGate, then pushed to the internet. Around central Scotland we are blessed with a fair few iGates, similarly Ireland is too.

You will notice one of the pictures below shows a line from my wx to Ayr (Specifically the Asda’s at Ayr) where the radio group meets, this information was passed to the internet not by gateway (iGate) but by smartphone. The following graphic shows a display of the weather at my QTH whilst I was away.





Note the two ships identified only by registration number, whilst to the right of the screen is “The Isle of Arran”


APRS reporting from my APRS enabled Android phone, on a visit down to Ayr Radio Group


APRS Wx report








This is just a graphical representation of what is going on, For more in depth articles I suggest looking at K9DCI’s Beginners Guide PDF/

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