a standard published in 2001, is the result of three years
of research funded by the Japanese government and administered
by the JARL to investigate digital technologies for amateur
radio. The research involved Japanese radio manufacturers
and other observers. Icom provided the equipment used for
development and testing. D-STAR radios and repeaters have
been tested extensively and are now ready for public use.
D-STAR is an open protocol – although it is published
by JARL, it is available to be implemented by anyone. (For
definitions and explanations of terms, there is a glossary
on page 6.) While Icom is the only company to date that manufactures
D-STAR-compatible radios, any equipment or software that supports
the D-STAR protocol will work with a D-STAR system. D-STAR
systems can be built using both commercial and homebrew equipment
a D-STAR system, the air link portion of the protocol applies
to signals travelling between radios or between a radio and
a repeater. D-STAR radios can talk directly to each other
without any intermediate equipment or through a repeater using
D-STAR voice or data transceivers. The gateway portion of
the protocol applies to the digital interface between D-STAR
repeaters (see figure 1). D-STAR also specifies how a voice
signal is converted to and from streams of digital data, a
function called a codec. The D-STAR codec is known as AMBE®
(Advanced Multi-Band Excitation) and the voice signal is transmitted
in the D-STAR system at 3600 bits/second (3.6 kbps).
The D-STAR system supports two types of digital data streams.
The Digital Voice (DV) stream used on 144 and 440 MHz contains
both digitized voice (3600 bps including error correction)
and digital data (1200 bps). Using a DV radio is like having
both a packet link and FM voice operating simultaneously.
The Digital Data (DD) stream, used only on 1.2 GHz, is entirely
data with a bit rate of 128k bps. The data connection to a
radio that uses DV is via an RS-232 interface or USB 1.0.
An Ethernet connection is used for high-speed DD D-STAR data.
Ordinary terminal emulation software (DV) or a Web browser
(DD) will do just fine for exchanging data (see figure 2).