DSTAR

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 standards to be widely deployed and sold by a major radio manufacturer that is designed specifically for amateur service use.

D-Star compatible radios are available on VHF and 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.

Technical details

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

Criticism D-STAR has been criticized for its use of a patented, closed-source proprietary voice codec (AMBE). Hams do not have access to the detailed specification of this codec or the rights to implement it on their own without buying a licensed product. Hams have a long tradition of building, improving upon and experimenting with their own radio designs. The modern digital age equivalent of this would be designing and/or implementing codecs in software. Critics say the proprietary nature of AMBE and its availability only in hardware form (as ICs) discourages innovation. Even critics praise the openness of the rest of the D-STAR standard which can be implemented freely. An open-source replacement for the AMBE codec would resolve this issue.

Bruce Perens, K6BP, amateur radio and open source advocate, has announced that he will investigate the development of an alternative codec.

Gateway server

The current gateway control software rs-rp2c version 2.0, more commonly called "Gateway 2.0", runs on virtually any 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. 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". 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 NICs, the "external" one being on a real 10.x.x.x network behind a router. A router that can NAT a single public IP address (can be static or dynamic in Gateway 2.0 systems) to a full 10.x.x.x/24 subnet mask 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 pair of addresses between the gateway and the controller.



Differences between Gateway 2.0 and Gateway 1.0 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 DNS FQDN 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 and Icom has announced a shut-down date for the U.S. Gateway 1.0 Trust Server, see "History" section.



 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.



 Manufacturers of D-STAR equipment Manufacturer Radio(s) Repeater(s) More Information Icom Yes Yes Kenwood No No (Kenwood "re-badges" an Icom radio in Japan which is not for sale outside Japan.) Moetronix DV Dongle No (Available through multiple amateur radio dealers.)



 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.

Kenwood D-STAR equipment Transceivers:

Kenwood TMW-706S: 2 m / 70 cm dual band digital voice mobile transceiver. Power up to 50 W. Kenwood TMW-706: 2 m / 70 cm dual band digital voice mobile transceiver. Power up to 20 W.
Note: These transceivers are not available in North America and appear to be OEM versions of the Icom ID-800H


Inet Labs Computer accessory:

DV-Dongle[8: USB device with AMBE codec, which can be used to generate D-STAR packets over the Internet through applications such as DVTOOL. Note: Available only through Ham Radio Outlet (search for model DV-DONGLE) or by homebrew using documentation at Moetronix.