D-STAR
D-STAR
D-STAR (Digital Smart Technologies for Amateur Radio) is an FDMA and GMSK digital voice and data protocol specification developed in the late 1990s as the result of research by the Japan Amateur Radio League to investigate digital technologies for amateur radio. While there are many other newer 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 voice signals offer clearer signals and use less bandwidth than their analogue 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 only manufacturer to offer D-STAR compatible radios is Icom. As of February 1, 2013, no other amateur radio equipment manufacturer has chosen to include D-STAR technology in their radios. The technology requires the use of a proprietary AMBE Codec that is owned by Digital Voice Systems, Inc.
D-STAR (Digital Smart Technologies for Amateur Radio) is an FDMA and GMSK digital voice and data protocol specification developed in the late 1990s as the result of research by the Japan Amateur Radio League to investigate digital technologies for amateur radio. While there are many other newer 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 voice signals offer clearer signals and use less bandwidth than their analogue 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 only manufacturer to offer D-STAR compatible radios is Icom. As of February 1, 2013, no other amateur radio equipment manufacturer has chosen to include D-STAR technology in their radios. The technology requires the use of a proprietary AMBE Codec that is owned by Digital Voice Systems, Inc.
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[citation needed] and administered by the Japan Amateur Radio League. In 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 (now K7DN), 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 440 MHz 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 and 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 some 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. The ID-1 was the first and only D-STAR radio that provides digital data (DD) mode operation. In this mode data via TCP/IP can be transferred at 128 kbit/s.
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 (Miniaturized satellite) 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 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 was scheduled for launch during early 2012. 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.
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[citation needed] and administered by the Japan Amateur Radio League. In 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 (now K7DN), 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 440 MHz 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 and 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 some 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. The ID-1 was the first and only D-STAR radio that provides digital data (DD) mode operation. In this mode data via TCP/IP can be transferred at 128 kbit/s.
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 (Miniaturized satellite) 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 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 was scheduled for launch during early 2012. 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, which is valuable to allow emergency communications oriented networks to continue to link in the event of internet access failure or overload.
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 digital voice mode (DV), a 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.
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, which is valuable to allow emergency communications oriented networks to continue to link in the event of internet access failure or overload.
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 digital voice mode (DV), a 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.
CRITICISMS
Proprietary Codec
D-STAR uses a patented, closed-source proprietary voice codec (AMBE). Amateurs do not have access to the specification of this codec or the rights to implement it on their own without buying a licensed product. Amateurs 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[citation needed] which can be implemented freely. An open-source replacement for the AMBE codec would resolve this issue. also 'vendor lock-in' is often cited as an issue with only one major manufacturer making most or all of the equipment.
Trademarked name
Despite many protestations from the Pro-D-STAR lobby that the standard was developed by the JARL and D-STAR is not only an Icom system, the mark 'D-STAR' is itself a registered trademark of Icom. According to the United States Patent and Trademark Office, a trademark is defined as "a word, phrase, symbol or design, or a combination of words, phrases, symbols or designs, that identifies and distinguishes the source of the goods of one party from those of others." While Icom does hold a trademark for its stylized D-STAR logo, Icom has made no attempt to patent the technology. The technology is now, and always was, open source.
Usable range compared to FM
D-STAR, like any digital voice mode has comparable usable range to FM, but it degrades differently. While the quality of FM progressively degrades the further a user moves away from the source, digital voice maintains a constant voice quality up to a point, then essentially "falls off a cliff". This behavior is inherent in any digital data system, and it demonstrates the threshold at which the signal is no longer correctable, and when data loss is too great, audio artefacts can appear in the recovered audio.
Emergency Communications Concerns
D-STAR's performance envelope relies heavily on internet connections. During widespread disasters that compromise commercial telecommunications infrastructure, D-STAR systems (and other modes that rely on the internet such as WinLink) may suffer outages or performance degradation that severely impacts operations. Without simulating such outages during drills, it is difficult to assess the impact of or establish D-STAR service recovery procedures in the event of such failures. As of the fall of 2011, there has been almost no discussion in the ham radio literature regarding actual drills where D-STAR systems were tested with completely failed or even intermittent telecommunications infrastructure. Comprehensive emergency communications plans used by ARES and other such organizations should address the possibility that such systems may not function as intended during major disasters.
Cost
D-STAR does significantly add to the cost of a radio, which is a barrier to the adoption of the technology. In 2006 the cost of a D-STAR radio was compared to that of a standard analog radio, and the price difference was nearly double. This is due partly to the per-unit cost for the voice codec hardware and/or license and partly to manufacturer research and development costs that need to be amortized. As is the case with any product, as more units are sold, the R&D portion of the cost will decrease over time. The D-STAR capable radios also cost more than their equivalents from other brands, even before the D-STAR options boards are added (in the UK as of April 2011, Martin Lynch & Sons' website lists the Icom 2820 (without D-STAR) at £489, while the equivalent Yaesu, the FT8800, is listed at just £337).
Proprietary Codec
D-STAR uses a patented, closed-source proprietary voice codec (AMBE). Amateurs do not have access to the specification of this codec or the rights to implement it on their own without buying a licensed product. Amateurs 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[citation needed] which can be implemented freely. An open-source replacement for the AMBE codec would resolve this issue. also 'vendor lock-in' is often cited as an issue with only one major manufacturer making most or all of the equipment.
Trademarked name
Despite many protestations from the Pro-D-STAR lobby that the standard was developed by the JARL and D-STAR is not only an Icom system, the mark 'D-STAR' is itself a registered trademark of Icom. According to the United States Patent and Trademark Office, a trademark is defined as "a word, phrase, symbol or design, or a combination of words, phrases, symbols or designs, that identifies and distinguishes the source of the goods of one party from those of others." While Icom does hold a trademark for its stylized D-STAR logo, Icom has made no attempt to patent the technology. The technology is now, and always was, open source.
Usable range compared to FM
D-STAR, like any digital voice mode has comparable usable range to FM, but it degrades differently. While the quality of FM progressively degrades the further a user moves away from the source, digital voice maintains a constant voice quality up to a point, then essentially "falls off a cliff". This behavior is inherent in any digital data system, and it demonstrates the threshold at which the signal is no longer correctable, and when data loss is too great, audio artefacts can appear in the recovered audio.
Emergency Communications Concerns
D-STAR's performance envelope relies heavily on internet connections. During widespread disasters that compromise commercial telecommunications infrastructure, D-STAR systems (and other modes that rely on the internet such as WinLink) may suffer outages or performance degradation that severely impacts operations. Without simulating such outages during drills, it is difficult to assess the impact of or establish D-STAR service recovery procedures in the event of such failures. As of the fall of 2011, there has been almost no discussion in the ham radio literature regarding actual drills where D-STAR systems were tested with completely failed or even intermittent telecommunications infrastructure. Comprehensive emergency communications plans used by ARES and other such organizations should address the possibility that such systems may not function as intended during major disasters.
Cost
D-STAR does significantly add to the cost of a radio, which is a barrier to the adoption of the technology. In 2006 the cost of a D-STAR radio was compared to that of a standard analog radio, and the price difference was nearly double. This is due partly to the per-unit cost for the voice codec hardware and/or license and partly to manufacturer research and development costs that need to be amortized. As is the case with any product, as more units are sold, the R&D portion of the cost will decrease over time. The D-STAR capable radios also cost more than their equivalents from other brands, even before the D-STAR options boards are added (in the UK as of April 2011, Martin Lynch & Sons' website lists the Icom 2820 (without D-STAR) at £489, while the equivalent Yaesu, the FT8800, is listed at just £337).