Part of our The Evolution of Amateur Radio timeline series.
Every digital voice mode I operate today, D-STAR on my FTX-1, DMR on my AnyTone, all traces back to a research project the Japanese government funded in the late 1990s. The result was D-STAR, and it holds a distinction none of the other digital voice modes can claim: it’s the only one actually designed from the ground up for amateur radio.
A government-funded research project
In 1998, Japan’s Ministry of Posts and Telecommunications funded a three-year research effort, administered by the Japan Amateur Radio League, to investigate digital technologies for amateur use. Japanese radio manufacturers and other observers took part in the research, with Icom providing much of the equipment used for development and testing. The result was published by the JARL in 2001 as D-STAR, short for Digital Smart Technologies for Amateur Radio.
How the signal actually works
D-STAR uses GMSK (Gaussian minimum-shift keying) modulation, a technique chosen for its spectral efficiency and its tolerance for the kind of signal degradation you get on a mobile or handheld radio moving through a fringe coverage area. On a voice repeater, the digital stream runs at 4800 bits per second total, split between roughly 2400 bps for the compressed AMBE-encoded voice itself and the remainder for the callsign routing data, forward error correction, and a small side channel that can carry low-speed data like short text messages alongside the voice. That side channel, small as it is, was genuinely novel for amateur voice repeaters at the time and is part of what let D-STAR support things like automatic position reporting over a voice channel.
DD mode and D-STAR’s data side
Voice repeaters get most of the attention, but the original D-STAR specification also defined a separate high-speed data mode, DD, running at 128 kbps on dedicated 23cm digital data repeaters rather than sharing bandwidth with a voice channel. DD mode never saw anywhere near the adoption that DV voice mode did, partly because it required its own dedicated repeater infrastructure and 23cm-capable equipment that most hams never bought, but it’s a reminder that D-STAR’s designers were thinking about amateur radio as a genuine data network from the very beginning, not just a digital replacement for FM voice.
An open protocol, mostly built by one company
D-STAR is technically an open protocol, published by JARL and available for anyone to implement. In practice, Icom has been the primary manufacturer of D-STAR gear since the beginning, first releasing commercial D-STAR-optional hardware starting in April 2004 with the IC-2200H, a 2 meter mobile radio. Kenwood adopted the standard more recently, giving hams a second major manufacturer option. One recurring point of criticism has been the AMBE voice codec itself, which is a proprietary, patented chip rather than an open standard, meaning anyone building D-STAR-compatible hardware or software has had to pay licensing fees or work around it, a tension that eventually spurred open-source alternatives like the DV Dongle and D-RATS software for hams who wanted to experiment with the protocol without buying into the proprietary vocoder chip.
Callsign routing sets it apart
What makes D-STAR distinct from the modes that followed is callsign-based routing. You program your own callsign into the radio, and the D-STAR gateway network lets you route a transmission to a specific station or reflector anywhere in the world by callsign, rather than relying purely on talkgroups. That’s a direct result of the mode being purpose-built for amateur use from day one instead of being adapted from a commercial standard.
The first of three, not the last
D-STAR had the digital voice space to itself for almost a decade before amateurs started adopting DMR, and over a decade before Yaesu launched its own competing standard. Those two are next in this series, and together with D-STAR they make up the three major digital voice modes still active on ham radio today.
Sources
Previous: 2000, when MURS opened. Next up: DMR crossing over from commercial radio.