Digital Radio Mondiale (DRM; ''mondiale'' being

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, a Romance ethnic group related to or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance languag ...

and French for "worldwide") is a set of

digital audio broadcasting Digital Audio Broadcasting (DAB) is a digital radio international standard, standard for broadcasting digital audio radio services in many countries around the world, defined, supported, marketed and promoted by the WorldDAB organisation. T ...

technologies designed to work over the bands currently used for analogue radio broadcasting including

AM broadcasting AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transm ...

—particularly

shortwave Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (app ...

—and

FM broadcasting FM broadcasting is a method of radio broadcasting that uses frequency modulation (FM) of the radio broadcast carrier wave. Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to transmit high fidelity, high-f ...

. DRM is more spectrally efficient than AM and FM, allowing more stations, at higher quality, into a given amount of

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

, using xHE-AAC

audio coding format An audio coding format (or sometimes audio compression format) is a content representation format for storage or transmission of digital audio (such as in digital television, digital radio and in audio and video files). Examples of audio coding f ...

. Various other

MPEG-4 MPEG-4 is a group of international standards for the compression of digital audio and visual data, multimedia systems, and file storage formats. It was originally introduced in late 1998 as a group of audio and video coding formats and related ...

codecs and Opus are also compatible, but the standard now specifies xHE-AAC. Digital Radio Mondiale is also the name of the international

non-profit A nonprofit organization (NPO), also known as a nonbusiness entity, nonprofit institution, not-for-profit organization, or simply a nonprofit, is a non-governmental (private) legal entity organized and operated for a collective, public, or so ...

consortium A consortium () is an association of two or more individuals, companies, organizations, or governments (or any combination of these entities) with the objective of participating in a common activity or pooling their resources for achieving a ...

that has designed the platform and is now promoting its introduction.

Radio France Internationale Radio France Internationale, usually referred to as RFI, is the State media, state-owned international radio news network of France. With 59.5 million listeners in 2022, it is one of the most-listened-to international radio stations in the world ...

TéléDiffusion de France TDF (which stands for ''Télédiffusion de France'' officially renamed ''TDF'' in 2004) is a French company which provides radio and television transmission services, services for telecommunications operators, and other multimedia services � ...

BBC World Service The BBC World Service is a British Public broadcasting, public service broadcaster owned and operated by the BBC. It is the world's largest external broadcaster in terms of reception area, language selection and audience reach. It broadcas ...

Deutsche Welle (; "German Wave"), commonly shortened to DW (), is a German state-funded television network, state-owned international broadcaster funded by the Federal Government of Germany. The service is available in 32 languages. DW's satellite tele ...

Voice of America Voice of America (VOA or VoA) is an international broadcasting network funded by the federal government of the United States that by law has editorial independence from the government. It is the largest and oldest of the American internation ...

Telefunken Telefunken was a German radio and television producer, founded in Berlin in 1903 as a joint venture between Siemens & Halske and the ''AEG (German company), Allgemeine Elektrizitäts-Gesellschaft'' (AEG) ("General electricity company"). Prior to ...

(now Transradio) and Thomcast (now Ampegon) took part at the formation of the DRM consortium. The principle of DRM is that bandwidth is the limiting factor, and computer processing power is cheap; modern CPU-intensive audio compression techniques enable more efficient use of available bandwidth, at the expense of processing resources.

Features

DRM can broadcast on frequencies below 30 MHz (

long wave In radio, longwave (also spelled long wave or long-wave and commonly abbreviated LW) is the part of the radio spectrum with wavelengths longer than what was originally called the medium-wave (MW) broadcasting band. The term is historic, datin ...

medium wave Medium wave (MW) is a part of the medium frequency (MF) radio band used mainly for AM radio broadcasting. The spectrum provides about 120 channels with more limited sound quality than FM stations on the FM broadcast band. During the daytim ...

and

short wave Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (app ...

), which allow for very-long-distance signal propagation. The modes for these lower frequencies were previously known as "DRM30". In the VHF bands, the term "DRM+" was used. DRM+ is able to use available broadcast spectra between 30 and 300 MHz; generally this means

band I Band I is a range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum. The first time there was defined "for simplicity" in Annex 1 of "Final acts of the European Broadcasting Conference in the VHF and ...

(47 to 68 MHz),

band II Band II is the range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum from 87.5 to 108.0 megahertz (MHz). Radio Band II is primarily used worldwide for FM radio broadcasting. Broadcast telev ...

(87.5 to 108 MHz) and

band III Band III is the name of the range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum from 174 to 240 megahertz (MHz). It is primarily used for radio and television broadcasting. It is also called h ...

(174 to 230 MHz). DRM has been designed to be able to re-use portions of existing analogue

transmitter In electronics and telecommunications, a radio transmitter or just transmitter (often abbreviated as XMTR or TX in technical documents) is an electronic device which produces radio waves with an antenna (radio), antenna with the purpose of sig ...

facilities such as antennas, feeders, and, especially for DRM30, the transmitters themselves, avoiding major new investment. DRM is robust against the fading and interference which often plague conventional broadcasting in these frequency ranges. The encoding and decoding can be performed with

digital signal processing Digital signal processing (DSP) is the use of digital processing, such as by computers or more specialized digital signal processors, to perform a wide variety of signal processing operations. The digital signals processed in this manner are a ...

, so that a low-cost

embedded system An embedded system is a specialized computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is e ...

with a conventional transmitter and receiver can perform the rather complex encoding and decoding. As a digital medium, DRM can transmit other data besides the audio channels (

datacasting Datacasting (data broadcasting) is the transmission of data over a wide area using radio waves. It typically refers to supplemental information sent by television stations alongside digital terrestrial television (DTT) signals. However, datacas ...

) — as well as RDS-type

metadata Metadata (or metainformation) is "data that provides information about other data", but not the content of the data itself, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive ...

program-associated data Program Associated Data (PAD) or Program Service Data (PSD) is the data displayed on many HD Radio and satellite radio receivers. It can describe the program being transmitted and other information such as the name of the song, the artist and the ge ...

Digital Audio Broadcasting Digital Audio Broadcasting (DAB) is a digital radio international standard, standard for broadcasting digital audio radio services in many countries around the world, defined, supported, marketed and promoted by the WorldDAB organisation. T ...

(DAB) does. DRM services can be operated in many different network configurations, from a traditional AM one-service one-transmitter model to a multi-service (up to four) multi-transmitter model, either as a

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. Analog AM and FM radio broadcast networks as well as digital broadcast networks can operat ...

(SFN) or

multi-frequency network Data networks, such as wireless communication networks, have to trade off between services customized for a single terminal and services provided to a large number of terminals. For example, the distribution of multimedia content to a large number ...

(MFN). Hybrid operation, where the same transmitter delivers both analogue and DRM services simultaneously is also possible. DRM incorporates technology known as Emergency Warning Features that can override other programming and activates radios which are in standby in order to receive emergency broadcasts.

Status

The technical standard is available free-of-charge from the

ETSI The European Telecommunications Standards Institute (ETSI) is an independent, not-for-profit, standardization organization operating in the field of Information and communications technology, information and communications. ETSI supports the de ...

, and the ITU has approved its use in most of the world. Approval for ITU region 2 is pending amendments to existing international agreements. The inaugural broadcast took place on June 16, 2003, in

Geneva Geneva ( , ; ) ; ; . is the List of cities in Switzerland, second-most populous city in Switzerland and the most populous in French-speaking Romandy. Situated in the southwest of the country, where the Rhône exits Lake Geneva, it is the ca ...

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

, at the ITU's World Radio Conference. Current broadcasters include Akashvani (formerly All India Radio),

, funklust (formerly known as BitXpress),

Radio Exterior de España Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connecte ...

Radio New Zealand International RNZ Pacific or Radio New Zealand Pacific, sometimes abbreviated to RNZP, is a division of Radio New Zealand and the official international broadcasting station of New Zealand. It broadcasts a variety of news, current affairs and sports programme ...

Vatican Radio Vatican Radio (; ) is the official broadcasting service of Vatican City. Established in 1931 by Guglielmo Marconi, today its programs are offered in 47 languages, and are sent out on short wave, DRM, medium wave, FM, satellite and the Internet. ...

Radio Romania International Radio Romania International (Romanian language, Romanian: ''Radio România Internațional'', or ''RRI'') is a Romania, Romanian radio station owned by the Romanian public radio broadcaster Societatea Română de Radiodifuziune (SRR, the national ...

and Radio Kuwait. Until now DRM receivers have typically used a

personal computer A personal computer, commonly referred to as PC or computer, is a computer designed for individual use. It is typically used for tasks such as Word processor, word processing, web browser, internet browsing, email, multimedia playback, and PC ...

. A few manufacturers have introduced DRM receivers which have thus far remained niche products due to limited choice of broadcasts. It is expected that the transition of national broadcasters to digital services on DRM, notably All India Radio, will stimulate the production of a new generation of affordable, and efficient receivers. Chengdu NewStar Electronics is offering the DR111 from May 2012 on which meets the minimum requirements for DRM receivers specified by the DRM consortium and is sold worldwide. The General Overseas Service of Akashvani broadcasts daily in DRM to Western Europe on 9.95 MHz at 17:45 to 22:30 UTC.

All India Radio All India Radio (AIR), also known as Akashvani (), is India's state-owned public broadcasting, public radio broadcaster. Founded in 1936, it operates under the Ministry of Information and Broadcasting (India), Ministry of Information and Broa ...

is in the process of replacing and refurbishing many of its domestic AM transmitters with DRM. The project which began in 2012 is scheduled to complete during 2015. The British Broadcasting Corporation

BBC The British Broadcasting Corporation (BBC) is a British public service broadcaster headquartered at Broadcasting House in London, England. Originally established in 1922 as the British Broadcasting Company, it evolved into its current sta ...

has trialled the technology in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

by broadcasting

BBC Radio Devon BBC Radio Devon is the BBC's local radio station serving the county of Devon. It broadcasts on FM, DAB, digital TV and via BBC Sounds from studios in the Mannamead area of Plymouth. According to RAJAR, the station has a weekly audience of ...

in the Plymouth area in the MF band. Th
trial
lasted for a year (April 2007 – April 2008). The

also trialed DRM+ in the

FM band The FM broadcast band is a range of radio frequencies used for FM broadcasting by radio stations. The range of frequencies used differs between different parts of the world. In Europe and Africa (defined as International Telecommunication Union ( ...

in 2010 from the Craigkelly transmitting station in

Fife Fife ( , ; ; ) is a council areas of Scotland, council area and lieutenancy areas of Scotland, lieutenancy area in Scotland. A peninsula, it is bordered by the Firth of Tay to the north, the North Sea to the east, the Firth of Forth to the s ...

, Scotland, over an area which included the city of

Edinburgh Edinburgh is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. The city is located in southeast Scotland and is bounded to the north by the Firth of Forth and to the south by the Pentland Hills. Edinburgh ...

. In this trial, a 10 kW (ERP) FM transmitter was replaced with a 1 kW DRM+ transmitter in two different modes, and coverage compared with FM. Digital Radio Mondiale was included in the 2007

Ofcom The Office of Communications, commonly known as Ofcom, is the government-approved regulatory and competition authority for the broadcasting, internet, telecommunications and mail, postal industries of the United Kingdom. Ofcom has wide-rang ...

consultation on the future of radio in the

for the AM medium wave band. RTÉ has also run single and multiple programme overnight tests during a similar period on the 252 kHz LW transmitter in Trim,

County Meath County Meath ( ; or simply , ) is a Counties of Ireland, county in the Eastern and Midland Region of Republic of Ireland, Ireland, within the Provinces of Ireland, province of Leinster. It is bordered by County Dublin to the southeast, County ...

, Ireland which was upgraded to support DRM after Atlantic 252 closed. The Fraunhofer Institute for integrated circuits IIS offers a package for software-defined radios which can be licensed to radio manufacturers
Software package for car radios with DRM – Digital Radio Mondiale
The DRM standard is not permitted in the US on the mediumwave or the VHF bands since the FCC accepted

HD Radio HD Radio (HDR) is a trademark for in-band on-channel (IBOC) digital radio broadcast technology. HD radio generally simulcast, simulcasts an existing analog radio station in digital format with less noise and with additional text information. HD R ...

as standard for these bands. However, the shortwave band is not blocked, but is not used regularly.

International regulation

On 28 September 2006, the

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

n spectrum regulator, the

Australian Communications and Media Authority The Australian Communications and Media Authority (ACMA) is an Australian government statutory authority within the Communications portfolio. ACMA was formed on 1 July 2005 with the merger of the Australian Broadcasting Authority and the Aus ...

, announced that it had "placed an embargo on frequency bands potentially suitable for use by broadcasting services using Digital Radio Mondiale until spectrum planning can be completed" "those bands being "5,950–6,200; 7,100–7,300; 9,500–9,900; 11,650–12,050; 13,600–13,800; 15,100–15,600; 17,550–17,900; 21,450–21,850 and 25,670–26,100 kHz. Since 2005, the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States government that regulates communications by radio, television, wire, internet, wi-fi, satellite, and cable across the United States. The FCC maintains j ...

states in that: "For digitally modulated emissions, the Digital Radio Mondiale (DRM) standard shall be employed." Part 73, section 758 is for HF broadcasting only.

Technological overview

Audio source coding

Useful bitrates for DRM30 range from 6.1 kbit/s (Mode D) to 34.8 kbit/s (Mode A) for a 10 kHz bandwidth (±5 kHz around the central frequency). It is possible to achieve bit rates up to 72 kbit/s (Mode A) by using a standard 20 kHz (±10 kHz) wide channel. (For comparison, pure digital

can broadcast 20 kbit/s using channels 10 kHz wide and up to 60 kbit/s using 20 kHz channels.) Useful bitrate depends also on other parameters, such as: * desired robustness to errors ( error coding) * power needed (

modulation Signal modulation is the process of varying one or more properties of a periodic waveform in electronics and telecommunication for the purpose of transmitting information. The process encodes information in form of the modulation or message ...

scheme) * robustness in regard to propagation conditions (

multipath propagation In radio communication, multipath is the propagation phenomenon that results in radio signals reaching the receiving antenna by two or more paths. Causes of multipath include atmospheric ducting, ionospheric reflection and refraction, and ...

doppler effect The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. The ''Doppler effect'' is named after the physicist Christian Doppler, who described ...

), etc. When DRM was originally designed, it was clear that the most robust modes offered insufficient capacity for the then state-of-the-art audio coding format

HE-AAC High-Efficiency Advanced Audio Coding (HE-AAC) is an audio coding format for lossy data compression of digital audio as part of the MPEG-4 standards. It is an extension of Low Complexity AAC (AAC-LC) optimized for low- bitrate applicati ...

(High Efficiency Advanced Audio Coding). Therefore, the standard launched with a choice of three different audio coding systems (source coding) depending on the bitrate: *

(High Efficiency Advanced Audio Coding). AAC is a perceptual coder suited for voice and music and the High Efficiency is an optional extension for reconstruction of high frequencies (SBR: spectral bandwidth replication) and stereo image (PS: Parametric Stereo). 24 kHz or 12 kHz sampling frequencies can be used for core AAC (no SBR) which correspond respectively to 48 kHz and 24 kHz when using SBR oversampling. *

CELP which is a parametric coder suited for voice only (vocoder) but that is robust to errors and needs a small bit rate. *

HVXC which is also a parametric coder for speech programs that uses an even smaller bitrate than CELP. However, with the development of

xHE-AAC, which is an implementation of MPEG

Unified Speech and Audio Coding Unified Speech and Audio Coding (USAC) is an data compression#Audio, audio compression format and audio codec, codec for both music and speech or any mix of speech and audio using very low bit rates between 12 and 64 kbit/s. It was developed b ...

, the DRM standard was updated and the two speech-only coding formats, CELP and HVXC, were replaced. USAC is designed to combine the properties of a speech and a general audio coding according to bandwidth constraints and so is able to handle all kinds of programme material. Given that there were few CELP and HVXC broadcasts on-air, the decision to drop the speech-only coding formats has passed without issue. Many broadcasters still use the

coding format because it still offers an acceptable audio quality at bitrates above about 15 kbit/s. However, it is anticipated that in future, most broadcasters will adopt xHE-AAC. DRM30, unlike HD Radio on the medium wave, allows multiprogramming.

Opus

Opus is an open-source codec not included in the DRM standard, but commonly supported by popular software implementations. Aside from perceived technical advantages over the MPEG family such as low latency (delay between coding and decoding), the codec is royalty-free and not subject to patent licensing. Equipment manufacturers currently pay royalties for incorporating the MPEG codecs. * Since version 2.1, Dream can broadcast using Opus format. * Spark supports CELT transmissions, which is a subset of Opus.

Bandwidth

DRM broadcasting can be done using a choice of different bandwidths: * 4.5 kHz. Gives the ability for the broadcaster to do a

simulcast Simulcast (a portmanteau of "simultaneous broadcast") is the broadcasting of programs or events across more than one resolution, bitrate or medium, or more than one service on the same medium, at exactly the same time (that is, simultaneously) ...

and use the lower-sideband area of a 9 kHz raster channel for AM, with a 4.5 kHz DRM signal occupying the area traditionally taken by the upper-sideband. However the resulting bit rate and audio quality is not good. * 5 kHz. Gives the ability for the broadcaster to do a simulcast and use the lower-sideband area of a 10 kHz raster channel for AM, with a 5 kHz DRM signal occupying the area traditionally taken by the upper-sideband. However the resulting bit rate and audio quality is marginal (7.1–16.7 kbit/s for 5 kHz). This technique could be used on the

bands throughout the world. * 9 kHz. Occupies half the standard bandwidth of a region 1 long wave or medium wave broadcast channel. * 10 kHz. Occupies half the standard bandwidth of a region 2 broadcast channel, and could be used to simulcast with analogue audio channel restricted to NRSC5. Occupies a full worldwide short wave broadcast channel (giving 14.8–34.8 kbit/s). * 18 kHz. Occupies full bandwidth of region 1 long wave or medium wave channels according to the existing

frequency plan The radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 Hz to 3,000 GHz (3 THz). Electromagnetic waves in this frequency range, called radio waves, are widely used in modern technology, particular ...

. This offers better audio quality. * 20 kHz. Occupies full bandwidth of region 2 or region 3 AM channel according to the existing frequency plan. This offers highest audio quality of the DRM30 standard (giving 30.6–72 kbit/s). * 100 kHz for DRM+. This bandwidth can be used in

, II, and III and DRM+ can transmit four different programs in this bandwidth or even one low definition digital video channel.

Modulation

The modulation used for DRM is coded orthogonal frequency division multiplexing (

COFDM In telecommunications, orthogonal frequency-division multiplexing (OFDM) is a type of digital transmission used in digital modulation for encoding digital (binary) data on multiple Carrier wave, carrier frequencies. OFDM has developed into a popul ...

), where every carrier is modulated with quadrature amplitude modulation ( QAM) with a selectable error coding. The choice of transmission parameters depends on signal robustness wanted and propagation conditions. Transmission signal is affected by noise, interference, multipath wave propagation and

Doppler effect The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. The ''Doppler effect'' is named after the physicist Christian Doppler, who described ...

. It is possible to choose among several error coding schemes and several modulation patterns: 64-QAM, 16-QAM and 4-QAM. OFDM modulation has some parameters that must be adjusted depending on propagation conditions. This is the carrier spacing which will determine the robustness against Doppler effect (which cause frequencies offsets, spread: Doppler spread) and OFDM guard interval which determine robustness against multipath propagation (which cause delay offsets, spread: delay spread). The DRM consortium has determined four different profiles corresponding to typical propagation conditions: * A: Gaussian channel with very little multipath propagation and Doppler effect. This profile is suited for local or regional broadcasting. * B: multipath propagation channel. This mode is suited for medium range transmission. It is nowadays frequently used. * C: similar to mode B, but with better robustness to Doppler (more carrier spacing). This mode is suited for long distance transmission. * D: similar to mode B, but with a resistance to large delay spread and Doppler spread. This case exists with adverse propagation conditions on very long distance transmissions. The useful bit rate for this profile is decreased. The trade-off between these profiles stands between robustness, resistance in regards to propagation conditions and useful bit rates for the service. This table presents some values depending on these profiles. The larger the carrier spacing, the more the system is resistant to Doppler effect (Doppler spread). The larger the guard interval, the greater the resistance to long multipath propagation errors (delay spread). The resulting low-

bit rate In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction ...

digital information is

modulated Signal modulation is the process of varying one or more properties of a periodic waveform in electronics and telecommunication for the purpose of transmitting information. The process encodes information in form of the modulation or message ...

using

. It can run in

mode by switching between DRM and AM, and it is also prepared for linking to other alternatives (e.g., DAB or FM services). DRM has been tested successfully on

mediumwave Medium wave (MW) is a part of the medium frequency (MF) radio band used mainly for AM broadcasting, AM radio broadcasting. The spectrum provides about 120 channels with more limited sound quality than FM stations on the FM broadcast band. Duri ...

(with 9 as well as 10

kHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base uni ...

channel spacing Channel spacing, also known as bandwidth, is a term used in radio frequency Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate o ...

) and

longwave In radio, longwave (also spelled long wave or long-wave and commonly abbreviated LW) is the part of the radio spectrum with wavelengths longer than what was originally called the medium-wave (MW) broadcasting band. The term is historic, dati ...

. There is also a lower bandwidth two-way communication version of DRM as a replacement for SSB communications on HF - note that it is ''not'' compatible with the official DRM specification. It may be possible in some future time for the 4.5 kHz bandwidth DRM version used by the Amateur Radio community to be merged with the existing DRM specification. The Dream software will receive the commercial versions and also limited transmission mode using the FAAC AAC encoder.

Error coding

Error coding can be chosen to be more or less robust. This table shows an example of useful bitrates depending on protection classes: * OFDM propagation profiles (A or B) * carrier modulation (16QAM or 64QAM) * and channel bandwidth (9 or 10 kHz) The lower the protection class the higher the level of error correction.

DRM+

While the initial DRM standard covered the broadcasting bands below 30 MHz, the DRM consortium voted in March 2005 to begin the process of extending the system to the VHF bands up to 108 MHz. On 31 August 2009, DRM+ (Mode E) became an official broadcasting standard with the publication of the technical specification by the

European Telecommunications Standards Institute The European Telecommunications Standards Institute (ETSI) is an independent, not-for-profit, standardization organization operating in the field of information and communications. ETSI supports the development and testing of global technical ...

; this is effectively a new release of the whole DRM spec with the additional mode permitting operation above 30 MHz up to 174 MHz. Wider bandwidth channels are used, which allows radio stations to use higher bit rates, thus providing higher audio quality. A 100 kHz DRM+ channel has sufficient capacity to carry one low-definition 0.7 megabit/s wide mobile TV channel: it would be feasible to distribute

mobile TV Mobile television is television watched on a small handheld or mobile device, typically developed for that purpose. It includes service delivered via mobile phone networks, received free-to-air via terrestrial television stations, or via satel ...

over DRM+ rather than DMB or

DVB-H DVB-H (digital video broadcasting - handheld) 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 2 ...

. However, DRM+ (DRM Mode E) as designed and standardized only provides bitrates between 37.2 and 186.3 kbit/s depending on robustness level, using 4-QAM or 16-QAM modulations and 100 kHz bandwidth. DRM+ has been successfully tested in all the VHF bands, and this gives the DRM system the widest frequency usage; it can be used in

, II ( FM-band) and III. DRM+ can coexist with DAB in

. The ITU has published three recommendations on DRM+, known in the documents as Digital System G. This indicates the introduction of the full DRM system (DRM 30 and DRM+). ITU-R Rec. BS.1114 is the ITU recommendation for sound broadcasting in the frequency range 30 MHz to 3 GHz. DAB, HD-Radio and ISDB-T were already recommended in this document as Digital Systems A, C and F, respectively. In 2011, the pan-European organisation Community Media Forum Europe has recommended to the European Commission that DRM+ should rather be used for small scale broadcasting (local radio, community radio) than DAB/DAB+.

References

External links

Digital Radio Mondiale (DRM) - official homepage

How to receive DRM on the long-, medium- and shortwave bands

DRM receiver. An open source DRM receiver written by th
Institute of Telecommunications
of th
University Kaiserslautern (Germany)

WinDRM
DRM software for

amateur radio Amateur radio, also known as ham radio, is the use of the radio frequency radio spectrum, spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emer ...

users
Dream - an open-source software DRM Receiver

gr-drm
GNU Radio transmitter implementation
DRM Software
DRM software collection
Global DRM transmissions schedule
{{Telecommunications Audiovisual introductions in 2003 2003 establishments in Switzerland Digital radio International broadcasting Open standards Radio hobbies