What is DRM?

The DRM Broadcasting system has been designed by broadcasters, for broadcasters, but with the active assistance

and participation of both transmitter & receiver manufacturers and other interested parties (such as regulatory

bodies). It has been designed specifically as a high quality digital replacement for current analogue radio

broadcasting in the AM and FM/VHF bands, and as such it can be operated with the same channelling and spectrum

allocations as currently employed. An overview of the frequency-bands where DRM operates is shown in Fig. 1

below.

 

 

The DRM standard describes a number of different operating modes, which may be broadly split into two groups as follows: ‘DRM30′ modes, which are specifically designed to utilise the AM broadcast bands below 30MHz, and

‘DRM+’ modes, which utilize the spectrum from 30MHz to VHF Band III, centred on the FM broadcast band II

DRM has received the necessary recommendations from the ITU, hence providing the international regulatory

support for transmissions to take place. The main DRM standard has been published by both the IEC and ETSI, but

ETSI publishes and is the main repository of the entire range of current DRM technical standards.

Apart from the ability to fit in with existing spectrum requirements, the DRM system also benefits from being an open

system. All manufacturers have free access to the complete technical standards, and are able to design and

manufacture equipment on an equitable basis. This has proved to be an important mechanism for ensuring the timely

introduction of new systems to the market and for accelerating the rate at which equipment prices reduce. This is a

significant consideration for broadcasters and even more for the listeners who will need to invest in new DRM-

capable receivers.

Key system features

The system is specifically designed to allow the new digital transmissions to co-exist with the current analogue

broadcasts, and a significant amount of work has been undertaken to quantify the operating parameters which assure

mutual analogue/digital compatibility. Hence the changeover from analogue to digital broadcasting can be phased

over a period of time, which in turn allows existing broadcasters to spread the required investment to meet any

budgetary constraints. Furthermore, unlike some other digital systems, the DRM system has been designed to allow

suitable analogue transmitters to be modified to switch easily between digital and analogue broadcasts. This can

significantly reduce the initial investment cost for a broadcaster. An additional budgetary benefit is the reduction of

transmission energy costs.

DRM exploits the unique propagation properties of the AM bands. The introduction of DRM30 services allows a

broadcaster to provide listeners with significantly improved audio quality and service reliability. As a result,

international broadcasters can provide services on SW and MW which are comparable to local FM services,

whilst enhancing the listener experience with easier tuning and added data services. National and local LW and

MW broadcasters will derive similar benefits.

In the VHF bands, DRM+ can be configured to use less spectrum than current stereo FM broadcasts, whilst

additionally deriving the potential benefits of increased robustness, reduced transmission power and/or increased

coverage.

DRM is unique in providing an extensive and extremely powerful “toolkit” of operating modes and techniques, which

allow a broadcaster to tailor the system to best meet the needs of his or her particular market. For instance, DRM

allows the independent selection modulation parameters (code-rates, constellation, guard-intervals etc). DRM also

supports both multi- and single-frequency network operation, (MFN/SFN), and hand-over to other networks (AF). This

latter feature allows a broadcaster operating on several different platforms to hand a listener from DRM to AM, FM or

DAB and back again. The appropriate signalling is intrinsically supported by DRM and DAB, and by data carriers on

AM and FM (AMSS and RDS respectively). Of particular note amongst the various data services is the DRM

Electronic Programme Guide (EPG), which allows listeners with appropriate receivers to access the broadcast

schedule and set recording times accordingly.

DRM has been successfully operated at power levels ranging from a few watts on 26MHz through to several hundred

kilowatts on long-wave. It is possible to utilise the one technical standard to provide coverage ranging from national

(c.1000 km) right down to local community (c.1 km radius).

Finally, there are three MPEG4 audio codecs included within the standard, catering for a wide range of bit-rates and

catering for both speech and music content.

Background: The DRM Consortium

The DRM Consortium (Digital Radio Mondiale) is an international not-for-profit organisation composed of

broadcasters, network providers, transmitter and receiver manufacturers, universities, broadcasting unions and

research Institutes. Its aim is to support and spread a digital broadcasting system suitable for use in all the frequency

bands up to and including VHF Band III. There are currently 93 members and 90 Supporters from 39 countries active

within the Consortium.

DRM was formed in Guangzhou, China in 1997, initially with the objective of “digitising” the AM broadcast bands up

to 30MHz (long, medium and short-wave). The DRM System Specification for broadcasting below 30MHz (”DRM30”)

was first published by ETSI in 2001.

Subsequently, a number of ancillary supporting standards were issued, including a Distribution and Communication

Protocol. In 2005 a decision was taken to extend the DRM system to incorporate modes designed to operate in the

VHF broadcasting bands. This required the addition of high-frequency modes, which, following refinement through

laboratory testing and field-trials, resulted in the publication of the current (extended) DRM specification ES 201 980

v3.1.1.

 

 

Benefits of Digital AM for ListenersMore choice

The average radio today can receive some 35-40 local FM stations and a handful of Medium Wave broadcasts.

DRM has the potential to bring to every radio a vast selection of new content. New programmes from the world’s

leading international broadcasters. Quality speech radio on Medium Wave, focusing on national and regional topics.

And, a world of community radios keen to find a voice.

No compromise in sound quality

The huge innovation that DRM brings is that Short Wave and Medium Wave broadcasts can now be heard in FM-like

sound quality. And reception is excellent anywhere – in cities and in dense forests, indoors in a block of flats and

outdoors while driving your car.

It is still a radio …

… and not a computer. Which means that you don’t need an internet connection to listen nor a Wi-Fi spot to tune in.

And because of this, it is truly portable and mobile. You can take a DRM radio anyplace and listen to what you want,

when you want, where you want.

A radio without boundaries

Because DRM is ideally suited to long range broadcasting, you can stay tuned to the same station as you cross

regional and national boundaries and move from one country to the next. Imagine, for example, driving across

Europe, for pleasure or as part of your job, and being able to stay tuned to your favourite radio station from back

home – absolutely not other system can deliver that.

All the benefits of digital radio

A low cost DRM receiver will deliver all the benefits associated with modern digital radios. You have access to an

Electronic Programme Guide (EPG) and you can tune in easily by frequency, station name or type of programme. In

addition, the programmes come with associated text information – the name of the station, the title of the programme

or record playing etc. And, as most DRM radios can also tune in to both the analogue FM and MW bands and DAB,

where available, this will be the one device you will need to listen to all your favourite radio content.

Benefits of Digital AM for BroadcastersExpand your reach

For broadcasters of all kinds, DRM is a godsend.

For major international broadcasters, like the BBC and Deutsche Welle, it is the obvious replacement for traditional

Short Wave transmissions. DRM allows direct access to millions of listeners in excellent sound quality, without the

hindrance of having to negotiate a way past the gatekeepers and at an excellent cost/reach ratio.

For specialised international broadcasters – for example, religious broadcasters – DRM is, so to speak, an answer to

a prayer. It allows them to reach the parts other systems cannot reach, for a fraction of the cost.

DRM on Medium Wave is perfect for broadcasters aiming for a national audience, especially in countries covering a

sizeable geographical area. In France, where the regulatory authorities have already approved DRM as the digital

successor to Medium Wave, two transmitters will cover the entire country. In large countries, like Russia or India,

DRM may be the only means to achieve seamless national coverage in the digital era – and it will certainly be the

most cost efficient.

DRM is also the ideal solution for regional Medium Wave coverage, on its own or as a complementary system to DAB

– it is with this latter option in mind that the BBC recently ran a successful DRM Medium Wave trial in South West

England. And, of course, DRM is simply perfect for broadcasters planning to roll out new, additional digital services

and generate new revenue streams without compromising their existing content offer.

But even for smaller broadcasters targeting well defined, urban niches, DRM has an answer. It is DRM+ and, subject

to regulatory approvals, it will allow community radios or specialised commercial broadcasters to reach their intended

audiences bypassing the congestion and high costs of the analogue FM band.

A cost efficient solution

DRM is a cost efficient solution all along the value chain.

Analogue Short and Medium Wave transmitters can be converted to DRM mode at low cost and the useful life of the

equipment significantly prolonged, both from a technical and a financial point of view.

The scope of the capital investment required is also manageable because just a few transmitters can achieve

excellent coverage over very extensive territories. Unlike other systems of digital audio broadcasting, DRM does not

require a large network of transmitters or a complicated lattice of repeaters to do the job.

Transmission revenue costs are no higher to those of analogue Short and Medium Wave broadcasts and offer

excellent value for money given the wide area coverage and the superior sound quality.

DRM has been developed to operate alongside other digital radio technologies and in the field of receivers the future

surely lies not with radio sets that are compatible just with one technical standard but with integrated hybrid tests that

work in the analogue bands and can also decode DAB/DMB signals. The integration of DRM capability into these

hybrid chipsets can be achieved at marginal cost, adding very little to the cost of the radio to the consumer.

Plug into the digital universe

While television is forging ahead with digital conversion and many countries have already set analogue switchover

dates in the first half of the next decade, radio is entering the digital era at a much slower pace. At the same time, the

triumph of the iPod and the expanding capacities of mobile phones, handhelds and laptops are leading people to

question whether radio has a digital future at all.

Well, radio does have a digital future, because of its immediacy and its portability and DRM will be an integral part of

that future. For radio to move into the digital world in step with other platforms, sound needs to be in a format that

these other platforms can understand – and the DRM standard provides that. The day that your DRM radio will be

talking to your mp3 player and your iPod is here.

DRM also provides enhanced digital features such as on-screen EPGs, data streams and pause live radio and rewind

functionality and it greatly facilitates interactivity with the audience.

Benefits of Digital AM for Manufacturers

Receiver, Transmitter and Semiconductor Manufacturers

Potentially, a vast new market

There are an estimated 2.5 billion analogue AM receivers currently in the world. As radio moves into the digital era,

these devices will be replaced and, potentially, the market as a whole will expand further. This is an unmissable

strategic opportunity. It is also worth noting that DRM is particularly to wide area coverage – hence, it is likely that it

will be adopted in countries stretching over large territories, such as Russia, China and India which also have large

populations and large markets.

A proven technology

The technology has been tested and continues to be tested across the globe, from Britain to Brazil. The results of the

trials have always been made openly available and their success has been endorsed by the leading professional and

scientific bodies in the industry. From a technological point of view, DRM is a mature, proven standard – no

shortcomings and no hidden surprises.

An open standard

Unlike some digital technologies, DRM is an open, non-proprietary standard. The DRM Consortium holds the IP

rights and licenses the technology to those organisations who want to use it and develop it further.

A complementary and versatile technology

DRM is fully compatible with the Eureka-147 standard on which the DAB and DMB technologies are based – indeed,

it complements that standard as DRM is currently best suited to the AM bands while DAB has been promoted as an

alternative to FM. More importantly, perhaps, in the short term, it is relatively straightforward and cost effective to

integrate DRM capabilities into a wide variety of devices – from hybrid radio sets with multi-band functionality to

handhelds and, soon, to mobile phones.

Get involved now, influence the future

The DRM consortium brings together some of the biggest names in the broadcasting industry. Members share ideas

and know-how and have the opportunity to influence not just technical developments but also, crucially, at this stage

the commercial strategy and the regulatory authorities as the Consortium gears up to bring the technology to market.

About the technology

DRM has near-FM sound quality plus the ease-of-use that comes from digital transmissions. The improvement over

AM is immediately noticeable. DRM can be used for a range of audio content, and has the capacity to integrate text

and data. This additional content can be displayed on DRM receivers to enhance the listening experience.

DRM uses the existing AM broadcast frequency bands and is designed to fit in with the existing AM broadcast band

plan, based on signals of 9 kHz or10 kHz bandwidth. It also has modes requiring only 4.5 kHz or 5 kHz bandwidth,

and modes that can take advantage of wider bandwidths – 18 kHz or 20 kHz – allowing DRM to operate alongside

AM transmissions in every market of the world.

The DRM system uses COFDM (Coded Orthogonal Frequency Division Multiplex). This means that all the data,

produced from the digitally encoded audio and associated data signals, is shared out for transmission across a large

number of closely spaced carriers. All of these carriers are contained within the allotted transmission channel. Time

interleaving is applied in order to mitigate against fading. Various parameters of the OFDM and coding can be varied

to allow DRM to operate successfully in many different propagation environments – the selection of the parameters

allows transmissions to be planned that find the best combination of transmit power, robustness and data capacity.

The DRM system uses MPEG 4 HE AAC v2 for mixed programming providing high quality at low data rates. In

addition, CELP and HVXC coders are available to provide speech-only programming at even lower data rates.

In 2005, the DRM Consortium decided to extend the DRM system under the project name DRM+ to operate in

all the broadcasting bands up to 174 MHz.

This range includes:

TV band (47 MHz to 68 MHz)

OIRT FM band (65.8 MHz to 74 MHz)

Japanese FM band (76 MHz to 90 MHz)

International FM band (87.5 MHz to 107.9 MHz)

DRM+ has a narrow bandwidth and is designed to fit in the FM broadcast band plan and a frequency grid of 100 kHz.

Its small spectrum needs supports its use in crowded bands. The high commonality with the existing DRM standard

allows easy and fast equipment implementation. DRM+ provides bit rates from 35 kbps to 185 kbps and, like DRM,

permits up to four services. It is therefore a flexible solution allowing single or small numbers of audio services to be

broadcast together. Before standardisation as a revision to the existing DRM System specification, ETSI ES 201 980,

the Consortium’s members will test and verify the design with both laboratory and field based tests.

Universal Standardisation

DRM: The World’s Only open standard, Universally Standardised Digital Radio System

DRM is the world’s only open standard, digital system for long-wave, medium-wave and short-wave and the VHF

bands, including the FM bands, with the ability to use existing frequencies and bandwidth across the globe.

DRM’s success in standardization and regulation with ETSI and the ITU is outlined below.

ETSI Standards

The DRM System Specification has been approved and published by the European Telecommunications Standards

Institute (ETSI). The standard has evolved from the original, which covered only the AM bands, to the current version

which includes operating modes for all the frequency bands below 300 MHz. In addition, ETSI has published

additional specifications that allow contribution and distribution networks to be built, and allow data applications in

addition to audio.  DRM is also able to transmit data applications designed for the DAB system, enabling authoring

tools and receiver decoders to be reused.

ETSI standards are openly published and free to download from FREE ETSI DOWNLOAD

ETSI standards for DRM are available from the DRM Specifications page 

ITU Regulation

The DRM Consortium has worked closely with the ITU and administrations to ensure that DRM can be deployed

globally.  ITU-R has published bothe system recommendations and planning parameter recommendations for DRM,

both for use in the AM bands and VHF bands.  In addition, digital transmission is often authorised in place of

analogue transmission provided that no greater amount of interference will be generated.

The most relevant ITU-R Recommendations are listed below:

System for digital sound broadcasting in the broadcasting bands below 30 MHz

“Planning parameters” for digital sound broadcasting at frequencies below 30 MHz

Systems for terrestrial digital sound broadcasting to vehicular, portable and fixed receivers in the frequency

range 30-3 000 MHz

Technical basis for planning of terrestrial digital sound broadcasting in the VHF band

DRM+

The Extension of DRM to VHF Frequencies

DRM+ is the name applied to the DRM standard when used in the VHF frequencies. The initiative to extend DRM

began with a vote at the 2005 General Assembly to begin the design, verification and testing of the parameters

needed to allow DRM to operate in the VHF broadcasting bands between; primarily Band I and Band II.

The design process began shortly afterwards and key decisions were made to ensure that the extension completely

shared the successful design philosophy of DRM – it is “DRM but at higher frequencies”.

Therefore, it has:

The same multiplex and signalling scheme

The same OFDM design (with new parameters)

The same audio codecs

DRM+ is implemented in the standard as robustness mode E. Its spectrum usage parameters are determined from

the internationally agreed norms in the FM band (88 to 108 MHz). Therefore it has an occupied bandwidth of 96 kHz

and a frequency grid of 100 kHz.

DRM+ provides bit rates from 35 kbps to 185 kbps at SNRs from 2 dB to 14dB and, like DRM, permits up to four

services. It is therefore a flexible solution allowing single or small numbers of audio services to be broadcast together.

Field Trial Results

During the process of gaining endorsement from the ITU for DRM’s extension to the VHF bands, test results from

various field trials conduscted around the world were submitted.  Some of the reports are avaialbel below:

ITU-WP6A-C-0532-E_Results of the DRM High Power field trial in the UK.pdf

ITU-WP6A-C-0512-E_Results of the DRM field trial in Band I in Turin.pdf

ITU-WP6A-C-0504-E_DRM Single Frequency Network field test results.pdf

ITU-WP6A-C-0503_E_Results of the DRM field trials in Sri Lanka.pdf