Digital radio
Encyclopedia
Digital radio has several meanings:
1. Today the most common meaning is digital radio broadcasting technologies, such as the digital audio broadcasting
(DAB) system, also known as Eureka 147. In these systems, the analog audio signal is digitized
into zeros and ones, compressed
using formats such as mp2
, and transmitted using a digital modulation scheme. The aim is to increase the number of radio programs in a given spectrum, to improve the audio quality, to eliminate fading
problems in mobile environments, to allow additional datacasting
services, and to decrease the transmission power or the number of transmitters required to cover a region. However, analog radio programs and equipment, especially for the FM broadcasting
system, still dominate the market.
2. An older and more wide definition, that still is used in communication engineering literature, is wireless
digital transmission technologies, i.e. microwave
and radio frequency communication standards where analog information
signals as well as digital data are carried by a digital signal
, by means of a digital modulation method. This definition includes broadcasting systems such at digital TV and digital radio broadcasting, but also two-way digital radio standards such as the second generation (2G
) cell-phones and later, short-range communication such as digital cordless phones, wireless computer networks, digital micro-wave radio links, deep space communication systems
such as communications to and from the two Voyager space probes
, etcetera.
3. A less common definition is radio receiver and transmitter implementations that are based on digital signal processing
, but may transmit or receive analog radio transmission standards, for example FM radio. This may reduce noise and distortion induced in the electronics. It also allows software radio implementations, where the transmission technology is changed just by selecting another piece of software. In most cases, this would however increase the energy consumption of the receiver equipment.
service. Digital radio broadcasting systems are typically designed for handheld mobile devices, just like mobile-TV systems, but as opposed to other digital TV systems which typically require a fixed directional antenna. Some digital radio systems provide in-band on-channel
(IBOC) solutions that may coexist with or simulcast with analog AM or FM transmissions, while others are designed for designated radio frequency bands. The latter allows one wideband radio signal to carry a multiplex
consisting of several radio-channels of variable bitrate as well as data services and other forms of media. Some digital broadcasting systems allow single-frequency network
(SFN), where all terrestrial transmitters in a region sending the same multiplex of radio programs may use the same frequency channel without self-interference
problems, further improving the system spectral efficiency.
While digital broadcasting offers many potential benefits, its introduction has been hindered by a lack of global agreement on standards. The Eureka 147 standard
(DAB) for digital radio is the most commonly used and is coordinated by the World DMB Forum, which represents more than 30 countries. This standard of digital radio technology was defined in the late 1980s, and is now being introduced in many countries. Commercial DAB receivers began to be sold in 1999 and, by 2006, 500 million people were in the coverage area of DAB broadcasts, although by this time sales had only taken off in the UK and Denmark
. In 2006 there are approximately 1,000 DAB stations in operation. There have been criticisms of the Eureka 147 standard and so a new 'DAB+' standard has been proposed.
To date the following standards have been defined for one-way digital radio:
See also software radio for a discussion of radios which use digital signal processing
.
(DAB), also known as Eureka 147, has been under development since the early eighties, has been adopted by around 20 countries worldwide. It is based around the MPEG-1 Audio Layer II
audio codec and this has been co-ordinated by the WorldDMB. DAB receivers are selling well in some markets.
WorldDMB announced in a press release in November 2006, that DAB would be adopting the HE-AACv2
audio codec, which is also known as eAAC+. Also being adopted are the MPEG Surround
format, and stronger error correction coding called Reed-Solomon coding. The update has been named DAB+. Receivers that support the new DAB standard began being released during 2007 with firmware updated available for some older receivers.
DAB and DAB+ cannot be used for mobile TV because they do not include any video codecs. DAB related standards Digital Multimedia Broadcasting
(DMB) and DAB-IP are suitable for mobile radio and TV both because they have MPEG 4 AVC and WMV9 respectively as video codecs. However a DMB video sub-channel can easily be added to any DAB transmission - as DMB was designed from the outset to be carried on a DAB subchannel. DMB broadcasts in Korea carry conventional MPEG 1 Layer II DAB audio services alongside their DMB video services.
has opted for a proprietary system called HD Radio(TM)
technology, a type of in-band on-channel
(IBOC) technology. Transmissions use orthogonal frequency-division multiplexing
, a technique which is also used for European terrestrial digital TV broadcast (DVB-T
). HD Radio technology was developed and is licensed by iBiquity
Digital Corporation. It is widely believed that a major reason for HD radio technology is to offer some limited digital radio services while preserving the relative "stick values" of the stations involved and to insure that new programming services will be controlled by existing licensees.
The FM digital schemes in the U.S. provide audio at rates from 96 to 128 kilobits per second (kbit/s), with auxiliary "subcarrier" transmissions at up to 64 kbit/s. The AM digital schemes have data rates of about 48 kbit/s, with auxiliary services provided at a much lower data rate. Both the FM and AM schemes use lossy compression techniques to make the best use of the limited bandwidth.
Lucent Digital Radio, USA Digital Radio (USADR), and Digital Radio Express commenced tests in 1999 of their various schemes for digital broadcast, with the expectation that they would report their results to the National Radio Systems Committee
(NRSC) in December 1999. Results of these tests remain unclear, which in general describes the status of the terrestrial digital radio broadcasting effort in North America
. Some terrestrial analog broadcast stations are apprehensive about the impact of digital satellite radio
on their business, while others plan to convert to digital broadcasting as soon as it is economically and technically feasible.
While traditional terrestrial radio broadcasters are trying to "go digital", most major US automobile manufacturers are promoting digital satellite radio. HD Radio technology has also made inroads in the automotive sector with factory-installed options announced by BMW, Ford, Hyundai, Jaguar, Lincoln, Mercedes, MINI, Mercury, Scion, and Volvo. Beyond the U.S., commercial implementation of HD Radio technology is gaining momentum around the world.
Satellite radio is distinguished by its freedom from FCC censorship in the United States
, its relative lack of advertising, and its ability to allow people on the road to listen to the same stations at any location in the country. Listeners must currently pay an annual or monthly subscription fee in order to access the service, and must install a separate security card in each radio or receiver they use.
Ford
and Daimler AG are working with Sirius Satellite Radio
, previously CD Radio, of New York City
, and General Motors and Honda
are working with XM Satellite Radio
of Washington, D.C.
to build and promote satellite DAB radio systems for North America, each offering "CD quality" audio and about a hundred channels.
Sirius Satellite Radio launched a constellation
of three Sirius satellites during the course of 2000. The satellites were built by Space Systems/Loral
and were launched by Russia
n Proton boosters. As with XM Satellite Radio, Sirius implemented a series of terrestrial ground repeaters where satellite signal would otherwise be blocked by large structures including natural structures and high-rise buildings.
XM Satellite Radio has a constellation of three satellites, two of which were launched in the spring of 2001, with one following later in 2005. The satellites are Boeing
(previously Hughes) 702 comsats, and were put into orbit by Sea Launch
boosters. Back-up ground transmitter
s (repeater
s) will be built in cities where satellite signals could be blocked by big buildings.
On February 19, 2007, Sirius Satellite Radio and XM Satellite Radio merged, to form Sirius XM Radio.
The FCC
has auctioned bandwidth allocations for satellite broadcast in the S band
range, around 2.3 GHz.
The perceived wisdom of the radio industry is that the terrestrial medium has two great strengths: it is free and it is local. Satellite radio is neither of these things; however, in recent years, it has grown to make a name for itself by providing uncensored content (most notably, the crossover of Howard Stern
from terrestrial radio to satellite radio) and commercial-free, all-digital music channels that offer similar genres to local broadcast favorites.
, 35.8% of the population owns a DAB
digital radio set and 25% of listening is to digital platforms.
40.5% of all adults, or 20.9 million people, listen to digital radio each week, according to RAJAR, which equates to 45% of all radio listeners.
The UK currently has the world's biggest digital radio network, with 103 transmitters, two nation-wide DAB ensemble
s and 48 local and regional DAB ensembles, broadcasting over 250 commercial and 34 BBC radio station
s; 51 of these stations are broadcast in London
. On DAB digital radio most listeners can receive around 20 additional stations, in addition to the analogue stations available on digital. The frequency band used is 217.5 to 230 MHz.
Some areas of the country are not yet covered by DAB but the BBC has announced plans to build out national coverage to 92% by the end of 2011 with 40 new transmitters being launched in 2011.
The Government will make a decision on a radio switchover subject to listening and coverage criteria being met. A digital radio switchover would maintain FM as a platform, while moving some services to DAB-only distribution. Digital radio stations are also broadcast on digital television
platforms such as Sky, Virgin Media and Freeview, as well as internet radio
.
, Brisbane
, Melbourne
, Perth
and Sydney
, and is being trialled in Canberra
and Darwin
.
is setting up a network of three satellites, including "AfriStar", "AsiaStar", and "AmeriStar", to provide digital audio information services to Africa
, Asia
, and Latin America
. AfriStar and AsiaStar are in orbit. AmeriStar cannot be launched from the United States
as Worldspace transmits on the L-band and would interfere with USA military as mentioned above..
Each satellite provides three transmission beams that can support 50 channels each, carrying news, music, entertainment, and education, and including a computer multimedia service. Local, regional, and international broadcasters are working with WorldStar to provide services.
A consortium of broadcasters and equipment manufacturers are also working to bring the benefits of digital broadcasting to the radio spectrum
currently used for terrestrial AM radio broadcasts, including international shortwave
transmissions. Over seventy broadcasters are now transmitting programs using the new standard, known as Digital Radio Mondiale
(DRM), and / commercial DRM receivers are available. DRM's system uses the MPEG-4
based standard aacPlus to code the music and CELP or HVXC for speech programs. At present these are priced too high to be affordable by many in the third world, however.
Low-cost DAB radio receivers are now available from various Japanese manufacturers, and WorldSpace has worked with Thomson Broadcast to introduce a village communications center known as a Telekiosk to bring communications services to rural areas. The Telekiosks are self-contained and are available as fixed or mobile units
(the number of phonecalls per MHz and base station, or the number of bit/s per Hz and transmitter, etc.) may be sufficiently increased. Digital radio transmission can also carry any kind of information whatsoever - just as long at it has been expressed as a sequence of ones and zeroes. Earlier radio communication systems had to be made expressly for a given form of communications: telephone
, telegraph, or television
, for example. All kinds of digital communications can be multiplexed or encrypted
at will.
1. Today the most common meaning is digital radio broadcasting technologies, such as the digital audio broadcasting
Digital audio broadcasting
Digital Audio Broadcasting is a digital radio technology for broadcasting radio stations, used in several countries, particularly in Europe. As of 2006, approximately 1,000 stations worldwide broadcast in the DAB format....
(DAB) system, also known as Eureka 147. In these systems, the analog audio signal is digitized
Digital audio
Digital audio is sound reproduction using pulse-code modulation and digital signals. Digital audio systems include analog-to-digital conversion , digital-to-analog conversion , digital storage, processing and transmission components...
into zeros and ones, compressed
Audio compression
Audio compression may refer to:*Audio compression , a type of lossy compression in which the amount of data in a recorded waveform is reduced for transmission with some loss of quality, used in CD and MP3 encoding, Internet radio, and the like...
using formats such as mp2
MPEG-1 Audio Layer II
MPEG-1 Audio Layer II or MPEG-2 Audio Layer II is a lossy audio compression format defined by ISO/IEC 11172-3 alongside MPEG-1 Audio Layer I and MPEG-1 Audio Layer III...
, and transmitted using a digital modulation scheme. The aim is to increase the number of radio programs in a given spectrum, to improve the audio quality, to eliminate fading
Fading
In wireless communications, fading is deviation of the attenuation that a carrier-modulated telecommunication signal experiences over certain propagation media. The fading may vary with time, geographical position and/or radio frequency, and is often modelled as a random process. A fading channel...
problems in mobile environments, to allow additional datacasting
Datacasting
Datacasting is the broadcasting of data over a wide area via radio waves. It most often refers to supplemental information sent by television stations along with digital television, but may also be applied to digital signals on analog TV or radio...
services, and to decrease the transmission power or the number of transmitters required to cover a region. However, analog radio programs and equipment, especially for the FM broadcasting
FM broadcasting
FM broadcasting is a broadcasting technology pioneered by Edwin Howard Armstrong which uses frequency modulation to provide high-fidelity sound over broadcast radio. The term "FM band" describes the "frequency band in which FM is used for broadcasting"...
system, still dominate the market.
2. An older and more wide definition, that still is used in communication engineering literature, is wireless
Wireless
Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications...
digital transmission technologies, i.e. microwave
Microwave
Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...
and radio frequency communication standards where analog information
Information
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...
signals as well as digital data are carried by a digital signal
Digital signal
A digital signal is a physical signal that is a representation of a sequence of discrete values , for example of an arbitrary bit stream, or of a digitized analog signal...
, by means of a digital modulation method. This definition includes broadcasting systems such at digital TV and digital radio broadcasting, but also two-way digital radio standards such as the second generation (2G
2G
2G is short for second-generation wireless telephone technology. Second generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja in 1991...
) cell-phones and later, short-range communication such as digital cordless phones, wireless computer networks, digital micro-wave radio links, deep space communication systems
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...
such as communications to and from the two Voyager space probes
Voyager program
The Voyager program is a U.S program that launched two unmanned space missions, scientific probes Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s...
, etcetera.
3. A less common definition is radio receiver and transmitter implementations that are based on digital signal processing
Digital signal processing
Digital signal processing is concerned with the representation of discrete time signals by a sequence of numbers or symbols and the processing of these signals. Digital signal processing and analog signal processing are subfields of signal processing...
, but may transmit or receive analog radio transmission standards, for example FM radio. This may reduce noise and distortion induced in the electronics. It also allows software radio implementations, where the transmission technology is changed just by selecting another piece of software. In most cases, this would however increase the energy consumption of the receiver equipment.
One-way digital radio standards
One-way standards are those used for audio and video broadcasting, and sometimes also datacasting, as opposed to those used for two-way communication. Digital radio broadcasting standards may provide terrestrial or satellite radioSatellite radio
Satellite radio is an analogue or digital radio signal that is relayed through one or more satellites and thus can be received in a much wider geographical area than terrestrial FM radio stations...
service. Digital radio broadcasting systems are typically designed for handheld mobile devices, just like mobile-TV systems, but as opposed to other digital TV systems which typically require a fixed directional antenna. Some digital radio systems provide in-band on-channel
In-band on-channel
In-band on-channel is a hybrid method of transmitting digital radio and analog radio broadcast signals simultaneously on the same frequency....
(IBOC) solutions that may coexist with or simulcast with analog AM or FM transmissions, while others are designed for designated radio frequency bands. The latter allows one wideband radio signal to carry a multiplex
Statistical multiplexing
Statistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation . In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bit-rate digital channels or data streams. The link sharing is adapted to the...
consisting of several radio-channels of variable bitrate as well as data services and other forms of media. Some digital broadcasting systems allow single-frequency network
Single-frequency network
A single-frequency network or SFN is a broadcast network where several transmitters simultaneously send the same signal over the same frequency channel.-Overview:...
(SFN), where all terrestrial transmitters in a region sending the same multiplex of radio programs may use the same frequency channel without self-interference
Interference
In physics, interference is a phenomenon in which two waves superpose to form a resultant wave of greater or lower amplitude. Interference usually refers to the interaction of waves that are correlated or coherent with each other, either because they come from the same source or because they have...
problems, further improving the system spectral efficiency.
While digital broadcasting offers many potential benefits, its introduction has been hindered by a lack of global agreement on standards. The Eureka 147 standard
Digital audio broadcasting
Digital Audio Broadcasting is a digital radio technology for broadcasting radio stations, used in several countries, particularly in Europe. As of 2006, approximately 1,000 stations worldwide broadcast in the DAB format....
(DAB) for digital radio is the most commonly used and is coordinated by the World DMB Forum, which represents more than 30 countries. This standard of digital radio technology was defined in the late 1980s, and is now being introduced in many countries. Commercial DAB receivers began to be sold in 1999 and, by 2006, 500 million people were in the coverage area of DAB broadcasts, although by this time sales had only taken off in the UK and Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
. In 2006 there are approximately 1,000 DAB stations in operation. There have been criticisms of the Eureka 147 standard and so a new 'DAB+' standard has been proposed.
To date the following standards have been defined for one-way digital radio:
Digital audio broadcasting systems
- Eureka 147 (branded as DABDigital audio broadcastingDigital Audio Broadcasting is a digital radio technology for broadcasting radio stations, used in several countries, particularly in Europe. As of 2006, approximately 1,000 stations worldwide broadcast in the DAB format....
) - DAB+
- Digital Radio Oceane
- ISDB-TSB
- Internet radioInternet radioInternet radio is an audio service transmitted via the Internet...
- FM band in-band on-channelIn-band on-channelIn-band on-channel is a hybrid method of transmitting digital radio and analog radio broadcast signals simultaneously on the same frequency....
(FM IBOC):- HD RadioHD RadioHD Radio, which originally stood for "Hybrid Digital", is the trademark for iBiquity's in-band on-channel digital radio technology used by AM and FM radio stations to transmit audio and data via a digital signal in conjunction with their analog signals...
(OFDM modulation over FM and AM band IBOC sidebandSidebandIn radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, containing power as a result of the modulation process. The sidebands consist of all the Fourier components of the modulated signal except the carrier...
s) - FMeXtraFMeXtraFMeXtra, now marketed as VuCast and oriented at the broadcast data market like MSN Direct, is an in-band on-channel digital radio broadcasting technology created by Digital Radio Express, now VuCast Media. Unlike iBiquity's HD Radio system, it uses any FM radio station's existing equipment and...
(FM band IBOC subcarrierSubcarrierA subcarrier is a separate analog or digital signal carried on a main radio transmission, which carries extra information such as voice or data. More technically, it is an already-modulated signal, which is then modulated into another signal of higher frequency and bandwidth...
s) - Digital Radio MondialeDigital Radio MondialeDigital Radio Mondiale is a set of digital audio broadcasting technologies designed to work over the bands currently used for AM broadcasting, particularly shortwave...
extension (DRM+) (OFDM modulation over AM band IBOC sidebandSidebandIn radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, containing power as a result of the modulation process. The sidebands consist of all the Fourier components of the modulated signal except the carrier...
s)
- HD Radio
- AM band in-band on-channelIn-band on-channelIn-band on-channel is a hybrid method of transmitting digital radio and analog radio broadcast signals simultaneously on the same frequency....
(AM IBOC):- HD RadioHD RadioHD Radio, which originally stood for "Hybrid Digital", is the trademark for iBiquity's in-band on-channel digital radio technology used by AM and FM radio stations to transmit audio and data via a digital signal in conjunction with their analog signals...
(AM IBOC sidebandSidebandIn radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, containing power as a result of the modulation process. The sidebands consist of all the Fourier components of the modulated signal except the carrier...
) - Digital Radio MondialeDigital Radio MondialeDigital Radio Mondiale is a set of digital audio broadcasting technologies designed to work over the bands currently used for AM broadcasting, particularly shortwave...
(branded as DRM) for the short, medium and long wave-bands
- HD Radio
- Satellite radioSatellite radioSatellite radio is an analogue or digital radio signal that is relayed through one or more satellites and thus can be received in a much wider geographical area than terrestrial FM radio stations...
:- WorldSpaceWorldSpace1worldspace, formerly known as 'WorldSpace', is a currently defunct satellite radio network that provided service to over 170,000 subscribers in eastern and southern Africa, the Middle East, and much of Asia with 96% coming from India...
in Asia and Africa - Sirius XM Radio in North America
- MobaHo!MobaHo!MobaHO! was a mobile satellite digital audio/video broadcasting service in Japan, whose services began on 20 October 2004 and ended on March 31, 2009 at 15:00. MobaHO! used digital broadcasting specification of ISDB...
in Japan and the Republic of (South) Korea
- WorldSpace
- Systems also designed for digital TV:
- DMBDigital Multimedia BroadcastingDigital Multimedia Broadcasting is a digital radio transmission technology developed in South Korea as part of the national IT project for sending multimedia such as TV, radio and datacasting to mobile devices such as mobile phones...
- DVB-HDVB-HDVB-H is one of three prevalent mobile TV formats. It is a technical specification for bringing broadcast services to mobile handsets. DVB-H was formally adopted as ETSI standard EN 302 304 in November 2004. The DVB-H specification can be downloaded from the official DVB-H website...
- DMB
- Low-bandwidth digital data broadcasting over existing FM radio:
- Radio Data SystemRadio Data SystemRadio Data System, or RDS, is a communications protocol standard for embedding small amounts of digital information in conventional FM radio broadcasts. RDS standardises several types of information transmitted, including time, station identification and programme information.Radio Broadcast Data...
(branded as RDS)
- Radio Data System
- Radio pagerPagerA pager is a simple personal telecommunications device for short messages. A one-way numeric pager can only receive a message consisting of a few digits, typically a phone number that the user is then requested to call...
s:- FLEXFLEX (protocol)FLEX is a communications protocol developed by Motorola and used in many pagers. FLEX provides one-way communication only , but a related protocol called ReFLEX provides two-way messaging....
- ReFLEXReFLEXReFLEX is a wireless protocol developed by Motorola which is used for two-way paging.The Motorola PageWriter released in 1996 was one of the first devices to use the ReFLEX network protocol.-Versions:...
- POCSAGPOCSAGPOCSAG is an asynchronous protocol used to transmit data to pagers. The name comes from Post Office Code Standardization Advisory Group, this being the British Post Office which used to run nearly all telecommunications in Britain before privatization....
- NTTNippon Telegraph and Telephone, commonly known as NTT, is a Japanese telecommunications company headquartered in Tokyo, Japan. Ranked the 31st in Fortune Global 500, NTT is the largest telecommunications company in Asia, and the second-largest in the world in terms of revenue....
- FLEX
Digital television broadcasting (DTV) systems
- Digital Video Broadcasting (DVB)
- Integrated Services Digital Broadcasting (ISDB)
- Digital Multimedia BroadcastingDigital Multimedia BroadcastingDigital Multimedia Broadcasting is a digital radio transmission technology developed in South Korea as part of the national IT project for sending multimedia such as TV, radio and datacasting to mobile devices such as mobile phones...
(DMB) - Digital Terrestrial TelevisionDigital terrestrial televisionDigital terrestrial television is the technological evolution of broadcast television and advance from analog television, which broadcasts land-based signals...
(DTTV or DTT) to fixed mainly roof-top antennas:- DVB-TDVB-TDVB-T is an abbreviation for Digital Video Broadcasting — Terrestrial; it is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in the UK in 1998...
(based on OFDM modulation) - ISDB-T (based on OFDM modulation)
- ATSC (based on 8VSB8VSB8VSB is the modulation method used for broadcast in the ATSC digital television standard. ATSC and 8VSB modulation is used primarily in North America; in contrast, the DVB-T standard uses COFDM....
modulation) - T-DMB
- DVB-T
- Mobile TVMobile TVMobile television usually means television watched on a small handheld device. It may be a pay TV service broadcast on mobile phone networks or received free-to-air via terrestrial television stations from either regular broadcast or a special mobile TV transmission format...
reception in handheld devices:- DVB-HDVB-HDVB-H is one of three prevalent mobile TV formats. It is a technical specification for bringing broadcast services to mobile handsets. DVB-H was formally adopted as ETSI standard EN 302 304 in November 2004. The DVB-H specification can be downloaded from the official DVB-H website...
(based on OFDM modulation) - MediaFLOMediaFLOMediaFLO is a technology developed by Qualcomm for transmitting audio, video and data to portable devices such as mobile phones and personal televisions, used for mobile television...
(based on OFDM modulation) - DMBDMBDMB is an acronym that may stand for:*Digital Multimedia Broadcasting*DaMarcus Beasley*Dave Matthews Band*Del McCoury Band*Delaware Memorial Bridge*Diamond Mind Baseball*Dimethylbutane...
(based on OFDM modulation) - Multimedia Broadcast Multicast ServiceMultimedia Broadcast Multicast ServiceMultimedia Broadcast Multicast Services is a point-to-multipoint interface specification for existing and upcoming 3GPP cellular networks, which is designed to provide efficient delivery of broadcast and multicast services, both within a cell as well as within the core network...
(MBMS) via the GSM EDGEEnhanced Data Rates for GSM EvolutionEnhanced Data rates for GSM Evolution is a digital mobile phone technology that allows improved data transmission rates as a backward-compatible extension of GSM...
and UMTS cellular networks - DVB-SHDVB-SHDVB-SH, Digital Video Broadcasting - Satellite services to Handhelds, is a physical layer standard for delivering IP based media content and data to handheld terminals such as mobile phones or PDAs, based on a hybrid satellite/terrestrial downlink and for example a GPRS uplink...
(based on OFDM modulation)
- DVB-H
- Satellite TV:
- DVB-SDVB-SDVB-S is an abbreviation for Digital Video Broadcasting — Satellite; it is the original Digital Video Broadcasting forward error coding and demodulation standard for satellite television and dates from 1994, in its first release, while development lasted from 1993 to 1997...
(for Satellite TV) - ISDB-S
- 4DTV4DTV4DTV is the name of a Television receive-only consumer satellite television tuner technology manufactured by Motorola for use with large-diameter parabolic satellite dish antennas on the C and Ku frequency bands on multiple satellites...
- S-DMBS-DMBS-DMB is a hybrid version of the Digital Multimedia Broadcasting. The S-DMB uses the S band of IMT-2000. and delivers around 18 channels at 128 kbps in 15 MHz. It incorporates a high power geostationary satellite, the MBSat 1...
- MobaHo!MobaHo!MobaHO! was a mobile satellite digital audio/video broadcasting service in Japan, whose services began on 20 October 2004 and ended on March 31, 2009 at 15:00. MobaHO! used digital broadcasting specification of ISDB...
- DVB-S
See also software radio for a discussion of radios which use digital signal processing
Digital signal processing
Digital signal processing is concerned with the representation of discrete time signals by a sequence of numbers or symbols and the processing of these signals. Digital signal processing and analog signal processing are subfields of signal processing...
.
DAB adopters
Digital Audio BroadcastingDigital audio broadcasting
Digital Audio Broadcasting is a digital radio technology for broadcasting radio stations, used in several countries, particularly in Europe. As of 2006, approximately 1,000 stations worldwide broadcast in the DAB format....
(DAB), also known as Eureka 147, has been under development since the early eighties, has been adopted by around 20 countries worldwide. It is based around the MPEG-1 Audio Layer II
MPEG-1 Audio Layer II
MPEG-1 Audio Layer II or MPEG-2 Audio Layer II is a lossy audio compression format defined by ISO/IEC 11172-3 alongside MPEG-1 Audio Layer I and MPEG-1 Audio Layer III...
audio codec and this has been co-ordinated by the WorldDMB. DAB receivers are selling well in some markets.
WorldDMB announced in a press release in November 2006, that DAB would be adopting the HE-AACv2
HE-AAC
High-Efficiency Advanced Audio Coding is a lossy data compression scheme for digital audio defined as a MPEG-4 Audio profile in ISO/IEC 14496-3. It is an extension of Low Complexity AAC optimized for low-bitrate applications such as streaming audio...
audio codec, which is also known as eAAC+. Also being adopted are the MPEG Surround
MPEG Surround
MPEG Surround , also known as Spatial Audio Coding is a lossy compression format for surround sound that provides a method for extending mono or stereo audio services to multi-channel audio in a backwards compatible fashion...
format, and stronger error correction coding called Reed-Solomon coding. The update has been named DAB+. Receivers that support the new DAB standard began being released during 2007 with firmware updated available for some older receivers.
DAB and DAB+ cannot be used for mobile TV because they do not include any video codecs. DAB related standards Digital Multimedia Broadcasting
Digital Multimedia Broadcasting
Digital Multimedia Broadcasting is a digital radio transmission technology developed in South Korea as part of the national IT project for sending multimedia such as TV, radio and datacasting to mobile devices such as mobile phones...
(DMB) and DAB-IP are suitable for mobile radio and TV both because they have MPEG 4 AVC and WMV9 respectively as video codecs. However a DMB video sub-channel can easily be added to any DAB transmission - as DMB was designed from the outset to be carried on a DAB subchannel. DMB broadcasts in Korea carry conventional MPEG 1 Layer II DAB audio services alongside their DMB video services.
United States
The United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
has opted for a proprietary system called HD Radio(TM)
HD Radio
HD Radio, which originally stood for "Hybrid Digital", is the trademark for iBiquity's in-band on-channel digital radio technology used by AM and FM radio stations to transmit audio and data via a digital signal in conjunction with their analog signals...
technology, a type of in-band on-channel
In-band on-channel
In-band on-channel is a hybrid method of transmitting digital radio and analog radio broadcast signals simultaneously on the same frequency....
(IBOC) technology. Transmissions use orthogonal frequency-division multiplexing
Orthogonal frequency-division multiplexing
Orthogonal frequency-division multiplexing is a method of encoding digital data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital communication, whether wireless or over copper wires, used in applications such as digital television and audio...
, a technique which is also used for European terrestrial digital TV broadcast (DVB-T
DVB-T
DVB-T is an abbreviation for Digital Video Broadcasting — Terrestrial; it is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in the UK in 1998...
). HD Radio technology was developed and is licensed by iBiquity
IBiquity
iBiquity Digital Corporation is a company formed by the merger of USA Digital Radio and Lucent Digital Radio, with the goal of creating an in-band on-channel digital radio system for the United States and around the world...
Digital Corporation. It is widely believed that a major reason for HD radio technology is to offer some limited digital radio services while preserving the relative "stick values" of the stations involved and to insure that new programming services will be controlled by existing licensees.
The FM digital schemes in the U.S. provide audio at rates from 96 to 128 kilobits per second (kbit/s), with auxiliary "subcarrier" transmissions at up to 64 kbit/s. The AM digital schemes have data rates of about 48 kbit/s, with auxiliary services provided at a much lower data rate. Both the FM and AM schemes use lossy compression techniques to make the best use of the limited bandwidth.
Lucent Digital Radio, USA Digital Radio (USADR), and Digital Radio Express commenced tests in 1999 of their various schemes for digital broadcast, with the expectation that they would report their results to the National Radio Systems Committee
National Radio Systems Committee
The National Radio Systems Committee is an organization sponsored by the Consumer Electronics Association and the National Association of Broadcasters . Its main purpose is to set industry technical standards for radio broadcasting in the United States...
(NRSC) in December 1999. Results of these tests remain unclear, which in general describes the status of the terrestrial digital radio broadcasting effort in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. Some terrestrial analog broadcast stations are apprehensive about the impact of digital satellite radio
Satellite radio
Satellite radio is an analogue or digital radio signal that is relayed through one or more satellites and thus can be received in a much wider geographical area than terrestrial FM radio stations...
on their business, while others plan to convert to digital broadcasting as soon as it is economically and technically feasible.
While traditional terrestrial radio broadcasters are trying to "go digital", most major US automobile manufacturers are promoting digital satellite radio. HD Radio technology has also made inroads in the automotive sector with factory-installed options announced by BMW, Ford, Hyundai, Jaguar, Lincoln, Mercedes, MINI, Mercury, Scion, and Volvo. Beyond the U.S., commercial implementation of HD Radio technology is gaining momentum around the world.
Satellite radio is distinguished by its freedom from FCC censorship in the United States
Censorship in the United States
In general, censorship in the United States, which involves the suppression of speech or other public communication, raises issues of freedom of speech, which is constitutionally protected by the First Amendment to the United States Constitution....
, its relative lack of advertising, and its ability to allow people on the road to listen to the same stations at any location in the country. Listeners must currently pay an annual or monthly subscription fee in order to access the service, and must install a separate security card in each radio or receiver they use.
Ford
Ford Motor Company
Ford Motor Company is an American multinational automaker based in Dearborn, Michigan, a suburb of Detroit. The automaker was founded by Henry Ford and incorporated on June 16, 1903. In addition to the Ford and Lincoln brands, Ford also owns a small stake in Mazda in Japan and Aston Martin in the UK...
and Daimler AG are working with Sirius Satellite Radio
Sirius Satellite Radio
Sirius Satellite Radio is a satellite radio service operating in North America, owned by Sirius XM Radio.Headquartered in New York City, with smaller studios in Los Angeles and Memphis, Sirius was officially launched on July 1, 2002 and currently provides 69 streams of music and 65 streams of...
, previously CD Radio, of New York City
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
, and General Motors and Honda
Honda
is a Japanese public multinational corporation primarily known as a manufacturer of automobiles and motorcycles.Honda has been the world's largest motorcycle manufacturer since 1959, as well as the world's largest manufacturer of internal combustion engines measured by volume, producing more than...
are working with XM Satellite Radio
XM Satellite Radio
XM Satellite Radio is one of two satellite radio services in the United States and Canada, operated by Sirius XM Radio. It provides pay-for-service radio, analogous to cable television. Its service includes 73 different music channels, 39 news, sports, talk and entertainment channels, 21 regional...
of Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
to build and promote satellite DAB radio systems for North America, each offering "CD quality" audio and about a hundred channels.
Sirius Satellite Radio launched a constellation
Satellite constellation
A group of artificial satellites working in concert is known as a satellite constellation. Such a constellation can be considered to be a number of satellites with coordinated ground coverage, operating together under shared control, synchronised so that they overlap well in coverage and...
of three Sirius satellites during the course of 2000. The satellites were built by Space Systems/Loral
Space Systems/Loral
Space Systems/Loral , of Palo Alto, California, is the wholly owned manufacturing subsidiary of Loral Space & Communications. It was acquired in 1990 for $715 million by Loral Corp. from Ford Motor Company as the Space Systems Division of Ford Aerospace...
and were launched by Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
n Proton boosters. As with XM Satellite Radio, Sirius implemented a series of terrestrial ground repeaters where satellite signal would otherwise be blocked by large structures including natural structures and high-rise buildings.
XM Satellite Radio has a constellation of three satellites, two of which were launched in the spring of 2001, with one following later in 2005. The satellites are Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...
(previously Hughes) 702 comsats, and were put into orbit by Sea Launch
Sea Launch
Sea Launch is a spacecraft launch service that uses a mobile sea platform for equatorial launches of commercial payloads on specialized Zenit 3SL rockets...
boosters. Back-up ground transmitter
Transmitter
In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...
s (repeater
Repeater
A repeater is an electronic device that receives asignal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.-Description:...
s) will be built in cities where satellite signals could be blocked by big buildings.
On February 19, 2007, Sirius Satellite Radio and XM Satellite Radio merged, to form Sirius XM Radio.
The FCC
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
has auctioned bandwidth allocations for satellite broadcast in the S band
S band
The S band is defined by an IEEE standard for radio waves with frequencies that range from 2 to 4 GHz, crossing the conventional boundary between UHF and SHF at 3.0 GHz. It is part of the microwave band of the electromagnetic spectrum...
range, around 2.3 GHz.
The perceived wisdom of the radio industry is that the terrestrial medium has two great strengths: it is free and it is local. Satellite radio is neither of these things; however, in recent years, it has grown to make a name for itself by providing uncensored content (most notably, the crossover of Howard Stern
Howard Stern
Howard Allan Stern is an American radio personality, television host, author, and actor best known for his radio show, which was nationally syndicated from 1986 to 2005. He gained wide recognition in the 1990s where he was labeled a "shock jock" for his outspoken and sometimes controversial style...
from terrestrial radio to satellite radio) and commercial-free, all-digital music channels that offer similar genres to local broadcast favorites.
- It must be noted that "Digital Radio" has a limited listening distance from the tower site. FCC laws currently show that 10% maximum digital signal of any US analog signal ratio. "There are still some concerns that HD Radio on FM will increase interference between different stations even though HD Radio at the 10% power level fits within the FCC spectral mask." HD RadioHD RadioHD Radio, which originally stood for "Hybrid Digital", is the trademark for iBiquity's in-band on-channel digital radio technology used by AM and FM radio stations to transmit audio and data via a digital signal in conjunction with their analog signals...
HD Radio#cite note-14. "HD Radio" is only 2 channels in the USA, side by side with analog stations. HD channel 1 may be on 93.2 FM, Analog station on 93.3, and HD channel 2 is on 93.4 FM. Differing stations are multicasting on different frequencies, respectively.
- Also note that "HD Radio" is digital radio, but is not "high definition" as most of the US population thinks. "HD" stands for "Hybrid Digital."
United Kingdom
In the United KingdomUnited Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, 35.8% of the population owns a DAB
Digital audio broadcasting
Digital Audio Broadcasting is a digital radio technology for broadcasting radio stations, used in several countries, particularly in Europe. As of 2006, approximately 1,000 stations worldwide broadcast in the DAB format....
digital radio set and 25% of listening is to digital platforms.
40.5% of all adults, or 20.9 million people, listen to digital radio each week, according to RAJAR, which equates to 45% of all radio listeners.
The UK currently has the world's biggest digital radio network, with 103 transmitters, two nation-wide DAB ensemble
DAB ensemble
DAB ensembles are groups of Digital audio broadcasting broadcasters transmitting multiple digital radio channels on a single radio transmission....
s and 48 local and regional DAB ensembles, broadcasting over 250 commercial and 34 BBC radio station
Radio station
Radio broadcasting is a one-way wireless transmission over radio waves intended to reach a wide audience. Stations can be linked in radio networks to broadcast a common radio format, either in broadcast syndication or simulcast or both...
s; 51 of these stations are broadcast in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
. On DAB digital radio most listeners can receive around 20 additional stations, in addition to the analogue stations available on digital. The frequency band used is 217.5 to 230 MHz.
Some areas of the country are not yet covered by DAB but the BBC has announced plans to build out national coverage to 92% by the end of 2011 with 40 new transmitters being launched in 2011.
The Government will make a decision on a radio switchover subject to listening and coverage criteria being met. A digital radio switchover would maintain FM as a platform, while moving some services to DAB-only distribution. Digital radio stations are also broadcast on digital television
Digital television
Digital television is the transmission of audio and video by digital signals, in contrast to the analog signals used by analog TV...
platforms such as Sky, Virgin Media and Freeview, as well as internet radio
Internet radio
Internet radio is an audio service transmitted via the Internet...
.
Australia
Australia commenced regular digital audio broadcasting using the DAB+ standard in May 2009, after many years of trialling alternative systems. Normal radio services operate on the AM and FM bands, as well as four stations (ABC and SBS) on digital TV channels. The services are currently operating in five state capital cities, namely, AdelaideAdelaide
Adelaide is the capital city of South Australia and the fifth-largest city in Australia. Adelaide has an estimated population of more than 1.2 million...
, Brisbane
Brisbane
Brisbane is the capital and most populous city in the Australian state of Queensland and the third most populous city in Australia. Brisbane's metropolitan area has a population of over 2 million, and the South East Queensland urban conurbation, centred around Brisbane, encompasses a population of...
, Melbourne
Melbourne
Melbourne is the capital and most populous city in the state of Victoria, and the second most populous city in Australia. The Melbourne City Centre is the hub of the greater metropolitan area and the Census statistical division—of which "Melbourne" is the common name. As of June 2009, the greater...
, Perth
Perth, Western Australia
Perth is the capital and largest city of the Australian state of Western Australia and the fourth most populous city in Australia. The Perth metropolitan area has an estimated population of almost 1,700,000....
and Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
, and is being trialled in Canberra
Canberra
Canberra is the capital city of Australia. With a population of over 345,000, it is Australia's largest inland city and the eighth-largest city overall. The city is located at the northern end of the Australian Capital Territory , south-west of Sydney, and north-east of Melbourne...
and Darwin
Darwin, Northern Territory
Darwin is the capital city of the Northern Territory, Australia. Situated on the Timor Sea, Darwin has a population of 127,500, making it by far the largest and most populated city in the sparsely populated Northern Territory, but the least populous of all Australia's capital cities...
.
Japan
Japan has started terrestrial sound broadcasting using ISDB-Tsb and MobaHO! 2.6 GHz Satellite Sound digital broadcastingKorea
On 1 December 2005 South Korea launched its T-DMB service which includes both television and radio stations. T-DMB is a derivative of DAB with specifications published by ETSI. More than 110,000 receivers had been sold in one month only in 2005.Developing nations
Digital radio is now being provided to the developing world. A satellite communications company named WorldSpaceWorldSpace
1worldspace, formerly known as 'WorldSpace', is a currently defunct satellite radio network that provided service to over 170,000 subscribers in eastern and southern Africa, the Middle East, and much of Asia with 96% coming from India...
is setting up a network of three satellites, including "AfriStar", "AsiaStar", and "AmeriStar", to provide digital audio information services to Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, and Latin America
Latin America
Latin America is a region of the Americas where Romance languages – particularly Spanish and Portuguese, and variably French – are primarily spoken. Latin America has an area of approximately 21,069,500 km² , almost 3.9% of the Earth's surface or 14.1% of its land surface area...
. AfriStar and AsiaStar are in orbit. AmeriStar cannot be launched from the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
as Worldspace transmits on the L-band and would interfere with USA military as mentioned above..
Each satellite provides three transmission beams that can support 50 channels each, carrying news, music, entertainment, and education, and including a computer multimedia service. Local, regional, and international broadcasters are working with WorldStar to provide services.
A consortium of broadcasters and equipment manufacturers are also working to bring the benefits of digital broadcasting to the radio spectrum
Radio spectrum
Radio spectrum refers to the part of the electromagnetic spectrum corresponding to radio frequencies – that is, frequencies lower than around 300 GHz ....
currently used for terrestrial AM radio broadcasts, including international shortwave
Shortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...
transmissions. Over seventy broadcasters are now transmitting programs using the new standard, known as Digital Radio Mondiale
Digital Radio Mondiale
Digital Radio Mondiale is a set of digital audio broadcasting technologies designed to work over the bands currently used for AM broadcasting, particularly shortwave...
(DRM), and / commercial DRM receivers are available. DRM's system uses the MPEG-4
MPEG-4
MPEG-4 is a method of defining compression of audio and visual digital data. It was introduced in late 1998 and designated a standard for a group of audio and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Experts Group under the formal standard ISO/IEC...
based standard aacPlus to code the music and CELP or HVXC for speech programs. At present these are priced too high to be affordable by many in the third world, however.
Low-cost DAB radio receivers are now available from various Japanese manufacturers, and WorldSpace has worked with Thomson Broadcast to introduce a village communications center known as a Telekiosk to bring communications services to rural areas. The Telekiosks are self-contained and are available as fixed or mobile units
Two-way digital radio standards
The key breakthrough or key feature in digital radio transmission systems is that they allow lower transmission power, they can provide robustness to noise and cross-talk and other forms of interference, and thus allow the same radio frequency to be reused at shorter distance. Consequently the spectral efficiencySpectral efficiency
Spectral efficiency, spectrum efficiency or bandwidth efficiency refers to the information rate that can be transmitted over a given bandwidth in a specific communication system...
(the number of phonecalls per MHz and base station, or the number of bit/s per Hz and transmitter, etc.) may be sufficiently increased. Digital radio transmission can also carry any kind of information whatsoever - just as long at it has been expressed as a sequence of ones and zeroes. Earlier radio communication systems had to be made expressly for a given form of communications: telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
, telegraph, or television
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
, for example. All kinds of digital communications can be multiplexed or encrypted
Encryption
In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...
at will.
- Digital cellular telephony (2G2G2G is short for second-generation wireless telephone technology. Second generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja in 1991...
systems and later generations):- GSM
- UMTS (sometimes called W-CDMA)
- TETRATetrathumb|right|250px|Pristella tetra — [[Pristella maxillaris]].thumb|right|250px|Golden Pristella tetra, a [[morph |morph]] of [[Pristella maxillaris]].thumb|right|250px|[[Silvertip tetra]] — Hasemania nana....
- IS-95IS-95Interim Standard 95 is the first CDMA-based digital cellular standard by Qualcomm. The brand name for IS-95 is cdmaOne. IS-95 is also known as TIA-EIA-95....
(cdmaOne) - IS-136 (D-AMPS, sometimes called TDMA)
- IS-2000 (CDMA2000)
- iDENIdenFor other uses of the word, see Iden The Iden was an English automobile manufactured from 1904 until 1907. Designed by George Iden, formerly of Daimler, they were four-cylinder 10/17 hp and 25/35 hp shaft-driven cars; each came with "Idens's frictionless radial gearbox"....
- Digital Mobile Radio:
- Project 25 a.k.a. "P25" or "APCO-25"
- TETRATetrathumb|right|250px|Pristella tetra — [[Pristella maxillaris]].thumb|right|250px|Golden Pristella tetra, a [[morph |morph]] of [[Pristella maxillaris]].thumb|right|250px|[[Silvertip tetra]] — Hasemania nana....
- NXDNNXDNNXDN is a Common Air Interface technical protocol for mobile communications. It was developed jointly by Icom Incorporated and Kenwood Corporation. was formed in order to promote the NXDN protocol in North and South America...
- Wireless networkWireless networkWireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise installations avoid the costly process of introducing cables into a building, or as a connection between various equipment...
ing:- Wi-FiWi-FiWi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
- HIPERLANHIPERLANHiperLAN is a Wireless LAN standard. It is a European alternative for the IEEE 802.11 standards . It is defined by the European Telecommunications Standards Institute . In ETSI the standards are defined by the BRAN project...
- BluetoothBluetoothBluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...
- DASH7DASH7DASH7 is an open source wireless sensor networking standard for wireless sensor networking, which operates in the 433 MHz unlicensed ISM band. DASH7 provides multi-year battery life, range of up to 2 km, low latency for connecting with moving things, a very small open source protocol...
- ZigBeeZigBeeZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on an IEEE 802 standard for personal area networks. Applications include wireless light switches, electrical meters with in-home-displays, and other consumer and industrial...
- 6LoWPAN6loWPAN6LoWPAN is an acronym of IPv6 over Low power Wireless Personal Area Networks. 6lowpan is the name of a working group in the internet area of the IETF....
- Wi-Fi
- Military radio systems for Network-centric warfareNetwork-centric warfareNetwork-centric warfare, also called network-centric operations, is a military doctrine or theory of war pioneered by the United States Department of Defense in the 1990's....
- JTRS (Joint Tactical Radio System- a flexible software-defined radio)
- SINCGARSSINCGARSSINCGARS is a Combat Net Radio currently used by U.S. and allied military forces. The radios, which handle voice and data communications, are designed to be reliable, secure and easily maintained...
(Single channel ground to air radio system)
- Amateur packet radioPacket radioPacket radio is a form of packet switching technology used to transmit digital data via radio or wireless communications links. It uses the same concepts of data transmission via Datagram that are fundamental to communications via the Internet, as opposed to the older techniques used by dedicated...
:- AX.25AX.25AX.25 is a data link layer protocol derived from the X.25 protocol suite and designed for use by amateur radio operators. It is used extensively on amateur packet radio networks....
- AX.25
- Digital modems for HF:
- PACTORPACTORPACTOR is a radio modulation mode used by amateur radio operators, marine radio stations, and radio stations in isolated areas to send and receive digital information via radio. A robust network of PACTOR stations has been established to relay data between radio stations and the Internet,...
- PACTOR
- Satellite radioSatellite radioSatellite radio is an analogue or digital radio signal that is relayed through one or more satellites and thus can be received in a much wider geographical area than terrestrial FM radio stations...
:- Satmodems
- Wireless local loopWireless local loopWireless local loop , is a term for the use of a wireless communications link as the "last mile / first mile" connection for delivering plain old telephone service and/or broadband Internet to telecommunications customers....
:- Basic Exchange Telephone Radio ServiceBasic Exchange Telephone Radio ServiceThe Basic Exchange Telephone Radio Service or BETRS is a fixed radio service where a multiplexed, digital radio link is used as the last segment of the local loop to provide wireless telephone service to subscribers in remote areas...
- Basic Exchange Telephone Radio Service
- Broadband wireless access:
- IEEE 802.16IEEE 802.16IEEE 802.16 is a series of Wireless Broadband standards authored by the Institute of Electrical and Electronics Engineers . The IEEE Standards Board in established a working group in 1999 to develop standards for broadband Wireless Metropolitan Area Networks...
- IEEE 802.16
External links
- "Digital, DTV, Internet, Mobile phone and MP3 Listening" - Dec 2006, RAJARRAJARRAJAR was established in 1992 to operate a single audience measurement system for the radio industry in the United Kingdom. RAJAR is jointly owned by the British Broadcasting Corporation and the RadioCentre...
organisation. - Online Terrestrial Radio - Search & and Listen to Live Radio Digitally
- Online Digital Radio - Select Station and Listen Live