Coming soon to NCAARC!!
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 20th 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.
For voice conversations, D-STAR repeaters act just like familiar analog 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!
Many data communications needs don’t require high-speeds, particularly for emergency communications. Status reports, damage assessment, shift changes, resource requests – all they take are a few keystrokes. D-STAR combines voice and low-speed data into a single channel simultaneously. There’s no need for a separate TNC and radio. Just connect your laptop or PDA and go.
A high-speed D-STAR connection looks just like an Ethernet connection to your laptop or other network device. Why run cables for a temporary or portable installation when mobile rigs will do the job? Connect across miles instead of meters! If a D-STAR repeater offers a broadband Internet connection, you have worldwide connectivity through your radio.
Emergency communications managers can put D-STAR’s high-speed data capabilities to work building systems that support their “served agency” with IT tools they understand and expect; email, file transfer, and Web browsing. Spreadsheets, graphics, maps, lists, Web pages – all flow easily through the D-STAR system.
If a picture is worth a thousand words, why not use D-STAR to paint the image? Weather and traffic information from the Internet are available via a D-STAR repeater’s broadband connection. Add a digital camera to a laptop and your D-STAR radio becomes a Web cam. Emergency management is greatly enhanced when images are available. The next time your group helps out on race day, D-STAR can make it possible to send photos at the finish line, on the course – anywhere your operators are.
D-STAR gateway protocols and software support linking repeater systems over a few miles or around the world. A regional group of repeaters create a D-STAR zone, working together and addressable in the D-STAR system as a unit. Whether you live in the wide-open spaces or a densely populated area, D-STAR repeaters can be tied together to make up the repeater system you want using either Internet or microwave links.
Repeaters linked with D-STAR can also share information using the same D-STAR link. This information includes repeater operating information and statistics. System designers can add entirely new functions, sharing weather and control information, for example. Another possibility is “smart systems” that track interference or user location.
If you’ve tried to coordinate a repeater channel on 2-meters or 440 MHz in any metropolitan area, you know how crowded the bands are! The D-STAR voice and low-speed data signal offers a significant improvement in spectrum efficiency, requiring only a 6 kHz channel instead of the 20, 25, or even 30 kHz of analog wide-band FM. As shown in figure 5, D-STAR repeaters can be interleaved between existing channels or multiple repeaters deployed in the spectrum of only one analog FM repeater.
As authorized users make their initial transmission to a D-STAR system, the call sign information attached to the digitized voice packets is recorded by the repeater controller. The controller then shares the information with other D-STAR systems through the D-STAR gateway registry. The registry is maintained on gateway servers located around the world as shown in figure 6 — currently Japan, the United States, and the UK. When an authorized D-STAR user makes a call to a call sign not currently registered on that repeater system, the registry allows the repeater controller to route the call to the repeater on which the targeted user was last registered.
|“D-STAR only works on 1.2 GHz.”Low-speed DV D-STAR voice and data works just fine at 144 and 440 MHz. 1.2 GHz supports the bandwidth needs of high-speed DD data. Choose the technology that satisfies your needs.|
|“There’s no difference between D-STAR and packet.”Even D-STAR’s lowest speed is competitive with the highest-performance packet systems available today. (See page 7 for detailed comparisons.) D-STAR’s simultaneous digital voice and data at 4800 bps is beyond the capability of any packet technology. High-speed D-STAR systems are ten times faster than the highest packet speeds.|
|“D-STAR is no different from IRLP or Echolink®”VOIP systems like IRLP and Echolink® are only capable of routing voice signals. They don’t support data exchange at any speed. Calls targeted to a specific user are not possible by any amateur technology except for D-STAR.|
|“D-STAR is just a digital party line!”The ability of D-STAR repeaters to route data and digitized voice worldwide sets it far apart from a simple party line. Sophisticated D-STAR controllers and gateways implement modern telecommunications functions in an amateur package.|
|“D-STAR is a replacement for broadband home Internet”Truly a fantasy! D-STAR can connect a user to the Internet, true, but all of the amateur radio restrictions on commercial activity still remain in place. D-STAR will provide the tools for a lot of great amateur innovation, but it’s not intended to replace Internet providers.|
|“I’ll be locked into Icom equipment forever.”While Icom is the first manufacturer to support D-STAR, any manufacturer or amateur can use the JARL standards to create equipment – transceivers, repeaters, and gateways – compatible with the D-STAR system. As the D-STAR system grows, look for other manufacturers to join the fun.|