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Further information: List of amateur radio modes
ICOM IC-91AD handheld transceiver with the D-STAR UT-121 digital voice board installed

D-STAR (Digital Smart Technologies for Amateur Radio) is a digital voice and data protocol specification developed as the result of research by the Japan Amateur Radio League to investigate digital technologies for amateur radio. While there are other digital on-air technologies being used by amateurs that have come from other services, D-Star is one of the first on-air and packet-based standards to be widely deployed and sold by a major radio manufacturer that is designed specifically for amateur service use.

Other non-digital voice modes such as amplitude modulation, frequency modulation, and single sideband have been widely used since the first half of the twentieth century. By comparison, digital D-STAR signals offer clearer signals and use less bandwidth than their non-digital counterparts. As long as the signal strength is above a minimum threshold, and no multi-path is occurring, the quality of the data received is better than an analog signal at the same strength.

D-Star compatible radios are available on VHF, UHF, and microwave amateur radio bands. In addition to the over-the-air protocol, D-Star also provides specifications for network connectivity, enabling D-Star radios to be connected to the Internet or other networks and provisions for routing data streams of voice or packet data via amateur radio callsigns.

The first manufacturer to offer D-Star compatible radios is Icom. As of December 30, 2008, no other amateur radio equipment manufacturer has chosen to include D-Star technology in their radios. Kenwood re-brands an Icom radio and distributes it in Japan only.

History

In 1999 an investigation was put into finding a new way of bringing digital technology to amateur radio. The process was funded by the Japanese government and administrated by the Japan Amateur Radio League. Several years later, during 2001, D-Star was published as the result of the research and Icom entered the construction of the new digital technology by offering the hardware necessary to create this technology.

In September 2003 Icom named Matt Yellen, KB7TSE, to lead its US D-Star development program.

Starting in April 2004 Icom began releasing new "D-Star optional" hardware. The first to be released commercially was a 2-meter mobile unit designated IC-2200H. Icom followed up with 2 meter and 440Mhz handheld transceivers the next year. However, the yet to be released UT-118 add-on card was required for these radios to operate in D-Star mode. Eventually Icom began selling the card once installed into the radios it provided D-Star connectivity for each of the transceivers. The June 2005 edition of the ARRL's QST magazine reviewed the Icom IC-V82.

JARL released significant changes to the existing D-Star standard in late 2004. Icom, aware that the changes were coming, had placed the release of their hardware on hold for a period of as much as a year while they awaited the changes. As soon as the changes were out, Icom announced they would be able to finish up and release equipment.

The Icom ID-1 1.2 GHz mobile radio was released in late 2004. This was to have been the first D-Star radio, providing full Digital Data (DD) functionality. This is the first dual-band 2-meter/70-centimeter mobile radio that is "D-Star Optional". It uses the optional UT-118 add-on card to provide D-Star digital voice.

The first D-Star over satellite QSO occurred between Michael, N3UC, FM-18 in Haymarket, Virginia and Robin, AA4RC, EM-73 in Atlanta, Georgia while working AMSAT's AO-27 microsatellite in 2007. The two operators used a variety of Icom gear to make the contact and experienced slight difficulty with doppler shift during the QSO.

As of late 2009 there are around 10,800 D-Star users talking through D-Star repeaters which have connectivity to the Internet via the G2 Gateway. There are around 550 G2 enabled repeaters now active. Note, these numbers do not include the scores of users with D-Star capabilities but not within range of a repeater, or working through D-Star repeaters that do not have Internet connectivity.

The first D-Star capable microsatellite is scheduled for launch during October 2010. OUFTI-1 is a CubeSat and is built by Belgian students at the University of Liège and I.S.I.L (Haute École de la Province de Liège). The name is an acronym for Orbital Utility For Telecommunication Innovation. The goal of the project is to develop experience in the different aspects of satellite design and operation. The satellite weighs just 1 kilogram and will utilize a UHF uplink and a VHF downlink.

Technical details

The system today is capable of linking repeaters together locally and through the Internet utilizing callsigns for routing of traffic. Servers are linked via TCP/IP utilizing proprietary "gateway" software, available from Icom. This allows amateur radio operators to talk to any other amateur participating in a particular gateway "trust" environment. The current master gateway in the United States is operated by the K5TIT group in Texas, who were the first to install a D-Star repeater system in the U.S.

D-STAR transfers both voice and data via digital encoding over the 2 m (VHF), 70 cm (UHF), and 23 cm (1.2 GHz) amateur radio bands. There is also an interlinking radio system for creating links between systems in a local area on 10 GHz.

Within the D-Star Digital Voice protocol standards (DV), voice audio is encoded as a 3600 bit/s data stream using proprietary AMBE encoding, with 1200 bit/s FEC, leaving 1200 bit/s for an additional data "path" between radios utilizing DV mode. On air bit rates for DV mode are 4800 bit/s over the 2 m, 70 cm and 23 cm bands.

In addition to DV mode, a high speed Digital Data (DD) mode can be sent at 128 kbit/s only on the 23 cm band. A higher-rate proprietary data protocol, currently believed to be much like ATM, is used in the 10 GHz "link" radios for site-to-site links.

Radios providing DV data service within the low-speed voice protocol variant typically use an RS-232 or USB connection for low speed data (1200 bit/s), while the Icom ID-1 23 cm band radio offers a standard Ethernet connection for high speed (128 kbit/s) connections, to allow easy interfacing with computer equipment.

Gateway server

The current gateway control software rs-rp2c version 2.0, more commonly called "Gateway 2.0", runs on virtually any distribution of Linux, but the Icom-supported and -recommended configuration is CentOS 5.1 on a Pentium IV 2.4 GHz or faster machine.

The recommended configuration uses Linux CentOS 5.1 with the latest updates, typically running (kernel 2.4.20. glibc 2.3.2 and BIND 9.2.1 or later). The CPU should be 2.4 GHz or faster and the memory should at least be 512 MB or greater. There should be two network interface cards and at least 10 GB free of hard drive space which includes the OS install. Finally for middleware, Apache 2.0.59, Tomcat 5.5.20, mod_jk2 2.0.4, OpenSSL 0.9.8d, J2SE 5.0 and postgreSQL 8.2.3 are utilized, but these can be different as updates occur.

Along with the open-source tools, the Icom proprietary dsipsvd or "D-Star IP Service Daemon" and a variety of crontab entries utilize a mixture of the local PostgreSQL and BIND servers to look up callsigns and "pcname" fields (stored in BIND) which are mapped to individual 10.x.x.x internal-only addresses for routing of both voice and data traffic between participating gateways.

During installation, the Gateway 2.0 software installation script builds most of the Web-based open-source tools from source for standardization purposes, while utilizing some of the packages of the host Linux OS, thus making CentOS 5.1 the common way to deploy a system, to keep incompatibilities from occurring in both package versions and configuration.

Additionally, gateways operating on the U.S. trust server are asked during initial setup to install DStarMonitor which is an add-on tool that allows the overall system administrators to see the status of each Gateway's local clock and other processes and PIDs needed for normal system operation, and also sends traffic and other data to servers operated under the domain name of "dstarusers.org". By this means a complete tracking of user behaviour is technically possible. Installation of this software also includes JavaAPRSd, a Java-based APRS interface which is utilized on Gateway 2.0 systems to interface between the Icom/D-Star GPS tracking system called DPRS to the more widely known and utilized amateur radio APRS system.

How Gateway 2.0 works

Each participating amateur station wanting to use repeaters/gateways attached to a particular trust server domain must "register" with a gateway as their "home" system, which also populates their information into the trust server a specialized central gateway system—which allows for lookups across a particular trust server domain. Only one "registration" per trust domain is required. Each amateur is set aside eight 10.x.x.x internal IP addresses for use with their callsign or radios, and various naming conventions are available to utilize these addresses if needed for specialized callsign routing. Most amateurs will need only a handful of these "registered" IP addresses, because the system maps these to callsigns, and the callsign can be entered into multiple radios.

The gateway machine controls two network interface controllers, the "external" one being on a real 10.x.x.x network behind a router. A router that can perform network address translation on a single public IP address (can be static or dynamic in Gateway 2.0 systems) to a full 10.x.x.x/8 network is required. From there, the Gateway has another NIC connected directly to the D-Star repeater controller via 10BaseT and the typical configuration is a 172.16.x.x (/24) pair of addresses between the gateway and the controller.

Differences between Gateway 1.0 and 2.0

The main differences between Gateway 1.0 and 2.0 are the addition of a relational database (PostgreSQL) for more flexibility and control of updates, versus the previous use of only BIND for "database" activities, the addition of both an administrative and end-user Web interface for registration which was previously handled via command-line commands by the Gateway 1.0 system administrators, dropping the requirement for static public IP addresses for gateways, and the ability of the software to use a fully qualified domain name to find and communicate with the trust server, allowing for redundancy/failover options for the trust server administrators. Finally, a feature called "multicast" has been added for administrators to be able to provide users with a special "name" they can route calls to which will send their transmissions to up to ten other D-Star repeaters at the same time. With cooperation between administrators a "multicast group" can be created for multiple repeater networks or other events.

Another additional feature of Gateway 2.0 is the ability to use callsign "suffixes" appended to the user's callsign in a similar fashion to the repeaters and gateways in the original system, which allow for direct routing to a particular user's radio or between two user radios with the same base callsign, by utilizing the 8th most significant field of the callsign and adding a letter to that location, both in the gateway registration process on the web interface, and in the radios themselves.

Gateway 1.0 control software

The Gateway 1.0 software was similar to Gateway 2.0, and utilized Fedora Core 2+ or Red Hat Linux 9+ OS on a Pentium-grade 2.4 GHz or faster machine.

Add-on software

Various projects exist for gateway administrators to add "add-on" software to their gateways, including the most popular package called "dplus" created by Robin Cutshaw AA4RC. A large number of Gateway 2.0 systems are offering services added by this software package to their end-users, and users are getting used to having these features. Features include the ability to link systems directly, "voice mail" (a single inbox today), ability to play/record audio to and from the repeaters connected to the Gateway and the most important, the ability for DV-Dongle users to communicate from the Internet to the radio users on the repeaters.

There is often a misconception by users and system administrators alike that the Gateway 2.0 systems have these add-on features from dplus by default, a testament to the popularity of this add-on software. Software development on dplus is very active right now, and features such as multiple repeater/system connections similar to the type of linking done by other popular repeater-linking systems (IRLP and EchoLink) are being worked on.

D-RATS

Further information: Amateur Radio Emergency Service

Another important aspect of D-STAR technology is its ability to send large quantities of data to emergency responders in the event of a disaster. Served agencies can instantly relate to sending e-mail or Microsoft Word files to someone. The quantity of data sent can be extremely high-volume compared to traditional amateur modes. Voice and even CW are capable of getting a message through albeit slowly, but D-STAR can place documents, images, and spreadsheets into the hands of those that need them most.

D-RATS is an emerging D-STAR communications tool that supports text chat, TCP/IP forwarding, file transfers, and can act as an e-mail gateway. There is also the ability to map user's positions using the D’PRS function of D-STAR. The application is written in Python/GTK and is cross-platform. It runs on Windows, Mac OS X, and Linux. The application was developed by Dan Smith (KK7DS) for the Washington County Amateur Radio Emergency Service in Oregon.

It was during the Great Coastal Gale of 2007 that the Washington County ARES group was able to put D-STAR to the test. The event was made up of several strong Pacific storms that interrupted conventional communication systems. Emergency traffic for the American Red Cross and the Vernonia, Oregon Fire Department was handled by the group using FM voice because the group had no D-Star repeater equipment available. The D*Chat communication tool was also used to send small text transmissions via simplex during this event at distances of up to seventeen miles.

An ability for amateurs to send files during this weather event would have greatly increased the capacity for ARES to help during the emergency. Although D*Chat was a useful means of communication D-RATS was developed to help fill the gaps that may have been lacking. Another improvement over D*Chat that D-RATS provides is form support. Users can set up frequently used forms well before they're necessary and when the need comes all that's required is to fill in the fields. In this way, for example, emergency forms from the Red Cross, National Traffic System, or the Incident Command System can be generated and quickly sent.

Criticism

As is usually the case with any new technology, there will be critics. Just as there were people that showed disdain when SSB was introduced, referring to it as "Duck Talk", there are people that express skepticism for D-Star. The problem is compounded by the fact that since D-Star started in Japan, original historical information is hard to come by when interested developers can't speak or read the source language. Along with this are the mistranslations, rumors, and assumptions that come with a new technology as people look to justify either for or against the new technology.

Criticism 1 - "D-Star uses a proprietary CODEC." True. Advanced Multi-Band Excitation (AMBE) is the proprietary speech coding standard developed by Digital Voice Systems, Inc. that is used in D-STAR.

Bruce Perens, K6BP, amateur radio and open source advocate, has announced that he will investigate the development of an alternative codec. The AMBE-2020 voice codec is the only proprietary element within the standard, and it is owned by DVSI, not Icom. Anyone can go to DVSI and purchase their own AMBE-2020 chip for about $20USD. Interested individuals will find many open projects being conducted within the D-Star community proving the standard is open, and Icom can't squelch the tinkering of the amateur radio community.

Criticism 2 - "D-Star doesn't have the range of FM." If the definition of range is being able to break squelch on an FM repeater, then this would be correct. D-Star doesn't have the range. However, if the definition of range refers to the ability to easily carry conversation at a comfortable level above background noise, then D-Star is comparable to FM. While the quality of FM degrades in a linear fashion the further a user moves away from the source, D-Star maintains a constant and guaranteed "armchair" voice quality up to a point, then essentially "falls off a cliff".

Criticism 3 - "It's too expensive." True, today it is. But more than 11,000+ D-Star enabled radios have been sold in the course of about five years. These sales can easily be considered to be the "early adopter" phase of the technology. Other manufacturers have to be looking at these numbers and making business decisions as to whether or not they should get into the market. As is the case with any product, the more that are made, and the more options that are available, the cheaper the price will become.

Another thing to consider is power output. Whether it's FM or D-Star, the power output of the transmitter will affect the overall range of the system. Currently, all commercial D-Star repeaters in the 2-meter and 70-centimeter bands sold by Icom transmit at about 25-watts. This is a fraction when compared to most FM repeaters and as such affects the total range of the system.

A non-Icom D-Star repeater

The world's first non-Icom D-Star repeater GB7MH, fully linked to the K5TIT G2 network and D-Plus, went live on 10 September 2009, in West Sussex, England. Whilst waiting for the DSL line installation, the repeater is connected to the Internet via a 3G dongle from network operator "Three". The system is built around Satoshi Yasuda's GMSK Node Adapter, a Mini-ITX system running CentOS 4, a Tait T800 repeater and G2 code written by G4ULF. All the usual G2 features such as callsign routing, D-Plus linkage and DPRS via D-Star Monitor are supported.

Source:- RSGB UK repeater website, www.ukrepeater.net

Compatible programs and projects

D-StarLet

A Web-based text messaging application using D-Star digital data technology.

D-StarLet is an open source client-server solution that allows content creation and modification from certain persons. D-StarLet interfaces with a D-Star radio through the serial port. It works with Windows (98+), Linux (Red Hat 7.3+), Apple Mac OS X, and others.

D-PRS interface

D-PRS is GPS for ham radio. Includes DStarTNC2, javAPRSSrvr, DStarInterface, and TNC-X

DStarMonitor

A Java application run on the repeater gateway PC which logs activity on the attached repeaters. Additional features include APRS object representation of each repeater.

DStarQuery

DStarQuery monitors the low-speed data stream of a D-STAR radio looking queries sent from a remote station. When a valid query is received, a predefined sequence is executed and the results transmitted from the station running DStarQuery. For example, a station transmits "?D*rptrs?" and it is received by a DStarQuery station which responds with a list of local repeaters.

The program D-PRS Interface includes a "Query" entry field that streamlines this process allowing the user to simply enter the desired command. Most DStarQuery systems will respond with a list of available commands when "?D*info?" is received.

Dstar Comms PRO

An advanced software application for use with DStar enabled radios. Supports advanced text chat, personal messaging with auto-reply and inbox, e-mail gateway and a beacon mode. GPS Tracking / Logging and a GPS Beacon emulator and Internet linking. New features are added weekly and users can suggest new features through the Dstar Comms forum. www.dstarcomms.com

DStar TV

Slow Scan TV for DStar radios and video streaming for Icom ID-1 by GM7HHB. Runs on Windows XP and Vista.

Home-brew D-Star radio

The first presumed D-Star radio including pictures and diagrams can be found at Moetronix.com's Digital Voice Transceiver Project. This page includes the schematic, source, and whitepaper.

Another project is Satoshi Yasuda's (7M3TJZ/AD6GZ) experiments with a UT-118 DV adapter. This project involves interfacing Icom's UT-118 with other manufacturer's amateur radio tranceivers. With this project some VHF/UHF/SHF amateur radio tranceivers are capable of being adapted for D-STAR operation. This requires access to the receiver's discriminator and to the direct FM modulator of the radio, sometimes available at a 9600 bit/s packet interface. Satoshi's product is no longer available. There is an alternative available at www.dutch-star.nl.

EA3CNO also has designed another interface based on a PIC microprocessor and UT-118 module.

Equipment

  • Icom D-STAR equipment
    • Transceivers:
    • Icom ID-1: 23 cm digital voice and digital data mobile transceiver. Power is selectable at 1 W or 10 W. USB control port and Ethernet connection for data.
    • Icom IC-2820H/IC-E2820: 2 m / 70 cm twin band digital voice mobile transceiver. Power up to 50 W on each band. May be purchased with or without D-STAR module. The D-STAR module includes a built-in GPS receiver with accompanying antenna.
    • Icom ID-800H: 2 m / 70 cm dual band digital voice mobile transceiver. Power up to 55 W on 2 m and 50 W on 70 cm.
    • Icom IC-92AD: 2 m / 70 cm twin band digital voice hand held transceiver. Four power settings up to 5 W on each band. Rugged and submersible design, optional microphone with embedded GPS.
    • Icom IC-91AD/IC-E91 + D-STAR: 2 m / 70 cm twin band digital voice hand held transceiver. Power is selectable at 0.5 W or 5 W on each band.
    • Icom IC-2200H: 2 m single band digital voice mobile transceiver. Power up to 65 W. Must purchase optional D-STAR module.
    • Icom IC-V82: 2 m single band digital voice hand held transceiver. Power up to 7 W. Must purchase optional D-STAR module.
    • Icom IC-U82: 70 cm single band digital voice hand held transceiver. Power up to 5 W. Must purchase optional D-STAR module.

    Note: All mobile (including hand-held) radios may also be used on conventional analog FM.
    Repeater equipment:

    • Icom ID-RP2000V: 2 m digital voice repeater.
    • Icom ID-RP4000V: 70 cm digital voice repeater.
    • Icom ID-RP2V: 23 cm digital voice repeater.
    • Icom ID-RP2D: 23 cm digital data access point.
    • Icom ID-RP2C: Repeater controller. Can support up to four digital voice repeaters and digital data access points. Required to operate any Icom D-STAR digital voice repeater or digital data access point.
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