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The first digital mode for amateur radio D-STAR

D-Star – the first digital amateur radio mode

D-STAR, 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 and software.

In 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).

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~ Digital Voice and Data ~

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. D-STAR can also be used on HF.

~ Worldwide Connections ~

For voice conversations, D-STAR repeaters act just like familiar analogue repeaters – everyone listening can hear your transmissions. Because your call sign is incorporated into every transmission, the D-STAR repeater “registers” your call sign and shares it around the D-STAR system.

If you travel into a new D-STAR repeater’s coverage area, register with a short transmission and your location will be quickly updated around the D-STAR network. This allows you to call someone registered with any other D-STAR repeater, no matter where that may be. If you call someone registered elsewhere, your voice will be routed to the appropriate repeater in digital form, where it is then heard just as you would expect if you were both using the same repeater!

~ Getting on air in VK ~

Simplex use is straight forward, but setting up repeater gateways can take a bit to get your head around. It may also pay to program your radio with a PC too. Have a look at the getting on air page on dstar.org.au for everything you need.

To transmit in D-STAR and have other people hear you, you’ll need to set four parameters: MYCALL, URCALL, RPT1, and RPT2.  Of course, you’ll also need to set the mode (“DV”) and frequency, and if you’re trying to talk through a repeater, the offset.

  • MYCALL is your own call sign, eight characters maximum.  You’re allowed to add “/” and then other characters; I think the original intent was so that you could sign “/P”, “/M”, or “/7”

 

  • URCALL can hold routing information or linking commands; to just use the local repeater, URCALL should be set to “CQCQCQ”.

 

  • RPT1 should be set to the local repeater and module that you’re trying to access.  (The setting doesn’t matter for simplex.)  See below for what I mean by a module.

 

  • RPT2 designates where you want your signal to be routed on your local repeater; normally RPT2 is set to the call sign of the local repeater, followed by “<space>G”.  (The setting doesn’t matter for simplex.)

Don’t get too excited about exactly what URCALL, RPT1, and RPT2 are for, because there is a simple web tool you can use that will tell you what to enter: the D-STAR Calculator.  Just tell the calculator what you want to do, and it will tell you what to put in MYCALL, URCALL, RPT1 and RPT2.  When using the calculator only change one thing at a time, and each time you change something the page will take several seconds to reload; be patient.  Hints: always select “Local Repeater with Gateway” rather than “Local Repeater”; have a look at the Calculator’s help page.

The “module”, “port”, or “node” (all three words mean the same thing) of a D-STAR repeater refers to the band.  Icom makes modules for 2m (144 MHz), 70cm (440 MHz), and 25cm (1.2 GHz), and a repeater can have nodes for more than one band; some D-STAR repeaters have modules for all three bands.

The “A” port or module is on 1.2 GHz, the “B” port is for 70cm, and the “C” port is for 2m.

~ Register  ~

Like DMR, you must register your callsign with a gateway. This is to ensure that only suitably licenced amateur radio operators can access a D-Star the D-Star network. D-Star Gateways enable users to connect from a local D-Star repeater, equipped with a D-Star Gateway, to any other Gateway equipped D-Star repeater.

Unlike DMR, you program your callsign into your radio. The D-Star network can support up to 8 variances of a callsign, based on the extension programmed into the user’s radio, but each callsign must be registered for access through a D-Star Gateway. This is particularly useful if a person has multiple D-Star radios that may be running at the same time, eg: Home, Car, Portable Hand Held, etc.

The real power of D-Star comes from being able to use a local repeater to access other repeaters and reflectors all around the world. You can’t use a DV-Dongle, DVAP or other similar devices without registering them. Use your registered callsign to get access to the D-Star Intranet.  Register here.

~ Bandwidth Comparison ~

Digital modes can differ in the bandwidth they use. The chart below will give you a good idea on which mode uses what. AS you can see, D-Star is lean and mean when it comes to bandwidth.

Digital Bandwidth Comparison

~ Reference sites ~

For more information about the mode that is D-Star and setting up and registering your radio, there are plenty of sites about that can help. In Australia, the main site is dstar.org.au. Here you’ll be able to find Australian centric information.

 

Rob Locher has a great getting started page here, and Icom Canada has a great D-Star paper too.

You must register your callsign to use the D-Star network.

 

You don’t need to register for simplex use.
Register at your local Australian gateway here.

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