D-STAR digital voice
A digital voice and data system for hams, developed in Japan.
What does it sound like?
A smooth, hissy digital rush.
Who uses it?
Amateur radio operators; many repeaters are linked worldwide.
Where and when can I hear it?
Ham VHF/UHF repeaters.
The science
D-STAR voice (DV mode) is a 4,800 bit-per-second stream, usually sent with GMSK, a smooth form of frequency shift keying that keeps the signal within about 6 kHz. Every 20 milliseconds the radio sends a 72-bit voice frame, 2.4 kbps of AMBE-coded speech plus error correction for 3.6 kbps total, alongside 24 bits of slow data for text and position reports. A resynchronization pattern repeats every 21 frames (420 milliseconds), so a listener tuning in mid-transmission can lock on, and each transmission starts with a header carrying the station and routing callsigns.
Why use it?
D-STAR's callsign routing lets an operator direct a call to a particular station or repeater through internet-linked gateways without knowing where that station is. The same radios also run analog FM, and the specification is an open protocol rather than a single company's product.
Lore
D-STAR, short for Digital Smart Technologies for Amateur Radio, was created by the Japan Amateur Radio League (JARL), whose English specification lists a provisional version released in September 2003. Icom says the protocol is recognized in the amateur band plans of more than 50 countries.
What do the decoded parts mean?
- Call signs: D-STAR headers carry the caller's and the destination's call signs.
Easily confused with
- System Fusion (C4FM) digital voice: System Fusion sounds harsher