The Internet of Digital Radio

Foundations of Amateur Radio

The Internet of Digital Radio

The topic of how radio evolves and embraces available technology is one that describes the hobby itself. From spark-gap through AM, SSB and FM our community picked up or invented solutions to make communication possible. When the internet came along it too became a tool ripe for picking and in 1997 a connection between a radio and the internet was made with the Internet Radio Linking Project or IRLP when Dave VE7LTD, a student at the University of British Columbia, joined the UBC Amateur Radio Society. Using a radio, some hardware and a computer, you could send audio between radios across the internet.

Since then this field has exploded with D-STAR, Echolink, DMR, AllStar, Wires, CODEC2, System Fusion and Brandmeister.

At a glance they’re all the same thing, radio + internet = joy.

Looking closer there are two distinct kinds of internet radio contraptions, those where the radio is digital and those where it’s not. IRLP is an example of an analogue radio connecting to hardware that does the encoding into digital and transmission across the internet. At the other end the reverse process, decoding, happens and another analogue radio is used to hear the result. This encoding and decoding is done by a piece of software called a CODEC.

If we continue for a moment down the analogue path, Echolink, AllStar and Wires do similar things. In 2002 Echolink made its way onto the scene, similar to IRLP, but it didn’t need any specialised hardware, any computer running the Echolink software could be used as both a client and a server, that is, you could use it to listen to Echolink, or you could use it to connect a radio to another Echolink computer.

AllStar, which started life in 2008 went a step further by making the linking completely separate. It uses the metaphor of a telephone exchange to connect nodes together, which is not surprising if you know that it’s built on top of the open source telephone switching software Asterisk.

In 2012 or so, Yaesu introduced Wires which is much like Echolink and AllStar. There are servers with rooms, not unlike chat rooms, where you connect a node to and in turn your radio.

Blurring the lines between these technologies happened when you could build a computer that spoke both IRLP and Echolink at the same time. Now you can also add AllStar to that mix.

Essentially these systems do similar things. They manage switching differently, handle DTMF differently, use a different audio CODEC and handle authentication in a variety of ways, but essentially they’re ways of connecting normal hand-held radios, generally FM, to each other via the internet using intermediary computers called nodes. Before you start sending angry letters, I know, there’s more to it, but I’ve got more to tell.

While Dave was busy in Canada inventing IRLP back in the late 1990’s, in Japan the Ministry of Posts and Telecommunications funded research, administered by the Japan Amateur Radio League into the digitisation of amateur radio. In 2001 that research resulted in what we know today as D-STAR. Two years later, ICOM started developing D-STAR hardware which resulted in actual physical radios less than a year later. Today you can get D-STAR hardware from ICOM, Kenwood and FlexRadio Systems.

Unlike the other technologies where the audio was converted at a central place, in D-STAR the audio is encoded in the radio and a digital signal is sent across the airwaves. That in turn means that the software that does the encoding, the CODEC, needs to be inside the radio.

Read the full article at https://forums.qrz.com/index.php?threads/the-internet-of-digital-radio.615204/. STRAY SIGNALS does not claim ownership of the article.

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