28 July 2019


Yesterday I was following an Amateur Radio balloon launch event put on by a nearby ham radio club, the Bill Gremillion Memorial Radio Club. The balloon carried an APRS tracker and all flight activity was available on the APRS.fi website. I was reminded just how great a service the APRS.fi site is, and figured it was time to give it some coverage.

When I stepped away from Amateur Radio a little over a decade ago the service known as APRS (Automatic Packet (not Position as many claim) Reporting System was moribund, kept alive by a few true believers. The decline in interest in APRS was due to a number of factors - the general decline in interest in packet radio with its slow AX.25 protocol (which APRS uses), and the kludginess and expense of much of the desktop client software. And then there's the ever present 'shiny new object' factor, so common in ham radio. New things like HF digital modes were becoming extremely popular and started drawing attention away from APRS.

APRS was developed in the 1980s by Bob Bruninga, WB4APR as a real-time local tactical communications system. I won't spend a whole lot of time reviewing the history of APRS, instead I'll let Bob lay it out, in an article he wrote in March of 1999 and updated in 2013.

One of the Achilles heels of APRS in the early years was the lack of good map interfaces. This was long before the availability of on-line services like Google Earth or Google Maps. There was some good client software available, but the map interfaces were either small scale wide area maps, many just roughly georeferenced screen captures, or the user had to buy a third party mapping program. I used the excellent UI-View software published by Roger Barker, G4IDE (SK), but had to purchase a mapping package called Precision Mapping (on CD) produced by a company called Undertow Software for an additional $50. There was a somewhat awkward relationship between UI-View and the Precision Mapping files, but it worked.

Fast forward a decade and things have changed - for the better. One of the things I noticed was the rise of the AX.25 'KISS' protocol. Ham radio manufacturers like Yaesu and Kenwood figured out it was easy and cheap to implement a KISS TNC in their radios, making them APRS ready right out of the box. Sadly, Icom seems to have forgotten about APRS since it developed a slavish devotion to DSTAR and it's 'sorta-like APRS' function known as DPRS.

Next is the development that I think really saved APRS - the excellent APRS.fi website.

APRS.fi web page showing a weather station feed - a very popular application

APRS.fi was launched in 2006 by Finnish developer Heikki Hannikainen, OH7LZB. APRS.fi uses the Google Maps application programming interface (API) to provide the worldwide map interface, and Heikki built a custom web platform that merges real-time APRS data and high resolution street maps (and satellite imagery), adds some user tools and makes it available freely to the Amateur Rado community. What APRS.fi does is remove the APRS client 'drama' that kept a lot of potential users at arm's length. With APRS.fi, APRS functionality is easily and immediately available on the web, on just about any hardware. If you can get to a web browser you can get to and use the APRS system.

There is a LOT going on behind the curtain with the APRS.fi system, and I'll let Heikki cover it in a presentation he did at the 2012 DCC conference in Atlanta. A bit geeky, but hey, we're all geeks, right?

With APRS.fi and a modern radio such as the Kenwood TH-D74 or the Yaesu FT2DR, which have built-in GPS receivers and APRS-ready KISS TNCs, there's no reason to not get active on APRS. So get out there and get tracking!

W8BYH out

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