Everybody hertz

There is a quiet revolution occurring in radio. Digital Radio Monidale, a new digital system for frequencies below 30MHz, is preparing to push short, medium and long wave radio signals back into the limelight after years of FM dominance, Digital Studio asks could this be the future of radio?

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By  Marcus Webb Published  November 26, 2002

Introduction|~||~||~|Within the broadcasting bands below 30MHz, audio is currently conveyed using amplitude modulation (AM). Hence the term ‘AM broadcasting bands,’ which include long, medium and short wave signals. There are currently more than two billion AM radio receivers worldwide all working on a universal standard. AM can broadcast over far greater distances than FM, making it a popular option in remote or developing countries which are out of FM’s limited reach.

Yet AM radio is not a popular choice amongst listeners. The reason being that since its inception AM radio has been hampered by sub-standard sound quality characterised by static, interference and fading. In the face of higher-quality audio options, such as FM and internet radio, consumers’ tolerance for AM noise plummeted, a move accelerated by the annoyance of having to search for stations. Some AM transmissions, such as short-wave, are affected by environmental factors such as changes in the ionosphere and sunspots forcing broadcasters to shuffle the frequencies on which their programmes air, causing frustration for listeners.

With all these problems, AM radio appears to be dying out as a popular medium. With FM frequencies offering listeners, and advertisers, a clear and robust sound, albeit over a smaller range, AM seems to be yesterday’s news. But now a new consortium is promising to bring yesterday’s technology bang up to date and lead it into a digital future.

“There is a global trend towards the adoption of digital technology in radio and communications, especially for distribution and transmission,” says Digital Radio Monidale chairman Peter Senger. “Digitalisation offers many substantial advantages to national/international broadcasters and infocasters.” The world is seeing the introduction of high quality delivery systems in homes. FM sound broadcasting is gradually moving to a DAB standard. But coverage on FM 88-108 MHz (VHF) is limited. “For many national and international broadcasters, the advantages of a complementary digital broadcast system below 30MHz are becoming clear,” says Senger.

“However, the limited fidelity of existing AM services is causing listeners to search for other alternatives. Implementation of digital radio in today’s AM bands will enable operators to provide services which will be successful with both existing and future high-quality services operating on other parts of the dial.”

||**||A new wave|~||~||~|A new wave

Formed in 1998, the DRM Consortium is an international group of more than 70 broadcasters, manufacturers, network operators, research institutions, broadcasting unions and regulatory bodies who aim to create and launch a universal, digital system (also called DRM) for the AM broadcasting bands

“Information across borders, worldwide availability on a single standard this is DRM; this is what we hope to achieve,” says Senger. “The advantages to the existing analogue system are huge.” The primary benefit of DRM is in the quality of the audio. At the moment the maximum quality achievable on analogue is 4.5 KHz. With DRM that will be boosted to 15 KHz, almost FM quality. Senger promises that DRM will also be free of the negative effects that have dogged long, medium and short wave bands. “With DRM there will be no more static noise, no more fading and no more interference,” he promises. “So you are getting the benefits of AM radio, the increased range, low costs and multitude of available frequencies, without the previous drawbacks.”

In addition, Senger claims, broadcasters will save a lot of money because digital transmitters use less than half the power of analogue. “Power is a big issue in a lot of countries,” he says. “Less power means less cost and less pollution, which is good news for everybody.”

The DRM system uses a type of transmission called 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. The DRM system is designed so that the number of carriers can be varied, depending on factors such as the allotted channel bandwidth and degree of robustness required.

The system can use three different types of audio coding, depending on broadcasters’ preferences. MPEG4 AAC audio coding, augmented by SBR bandwidth extension, is used as a general-purpose audio coder and provides the highest quality. MPEG4 CELP speech coding is used for high quality speech coding where there is no musical content. HVXC speech coding can be used to provide a very low bit-rate speech coder.

Unlike digital systems that require a new frequency allocation, DRM uses existing AM broadcast frequency bands. The DRM signal is designed to fit in with the existing AM broadcast band plan, based on signals of 9KHz or 10KHz bandwidth. It has modes requiring as little as 4.5KHz or 5KHz bandwidth, plus modes that can take advantage of wider bandwidths, such as 18 or 20KHz.

“DRM offers the chance to link the old analogue transmission into the new digital future, otherwise it will die out,” proclaims Senger. “DRM can broadcast on existing transmission equipment you just need an additional tool, which costs around ten percent of a new transmitter. You do not need a new frequency and during the interim stage, you can broadcast on analogue, digital or simulcast.”

While the digital signal during simulcast is not as powerful as if you were broadcasting a solely digital signal, it does mean you can continue to serve your existing analogue audience whilst offering better quality to those that have upgraded. The new receiver debuted at this year’s IBC show in Amsterdam. A software receiver, the device can be used to receive any type of radio broadcast; DRM, DAB and analogue.

But with FM already well established as the frequency of choice, why should people upgrade their receivers to DRM? “If you compare this system to FM, FM can only transmit over a short distance, approximately a 100 km diameter,” says Senger. “Medium wave and short wave, particularly short wave, can broadcast around the world from a single transmitter. Therefore, if you have to cover a large country or wish to broadcast to other countries, as companies such as DeutscheWelle does, then FM will not help you. Also, most of the FM frequencies are already taken or are very expensive.”

||**||Arabic interest|~||~||~|Arabic interest

According to Senger, the Middle East region would benefit greatly from DRM. “There is a lot of interest in the Arabic regions. We hope that many, if not all, Arabic broadcasters with short or medium wave transmission will look into this new digital system and see the benefits on offer,” he says. “There is a lot of medium and short wave radio in the region already. By changing to DRM the Middle East would benefit from improved qualities, more programmes and parallel news channels.”

By upgrading to DRM the area would also be open to worldwide broadcasts. DeutscheWelle, for example, already broadcasts to the area in Arabic, English and German and Senger hopes that “a new, high-quality, digital signal will offer existing listeners a better quality of service, while attracting new audiences.”

To date, DRM has three members from the Middle East region, Arab States Broadcasting Union (Tunisia), Libyan Jamahiriya Broadcasting (Libya) and Arab Gulf Countries Cooperation Council (Saudi Arabia) have signed up to the DRM a number DRM's commercial committee chairman, Michel Penneroux of TDF, France, hopes to increase.
“As the chairman of the commercial committee I have a commercial policy of establishing regional, or national, commercial platforms,” he says. “For example there is already a German group, a French group for DRM and so on. With the recent subscription of the Arab Gulf Countries Cooperation Council, we have decided to create a Middle Eastern group for DRM.”

According to Penneroux, this process is already underway, and he is already in discussion with some major players across the Middle East. “We are drawing together international and national broadcasters, retailers, manufacturers, car manufacturers and national regulatory bodies to discuss all aspects of employing the DRM system in the Gulf,” he says.

||**||Unasked question|~||~||~|Unasked questions

In October, the International Telecommunications Union (ITU) recommended DRM for all 3 Broadcasting Bands below 30 MHz, the first time a digital radio system has received such broad recommendation, but not everyone is convinced.

Speaking with Dick Hobbs recently he described Digital Radio Monidale, as “the answer to the question nobody is asking.” “People are not asking questions yet because people do not know of the advantages yet,” counters Senger. “Once the people know about DRM they will be crying out for it, but at the moment people cannot imagine that such a high-quality broadcast is available over such long distances. It is truly amazing to compare the differences of analogue and digital, once you experience digital you will never go back.

“Ultimately,” Senger concludes, “we hope to kill of the analogue system completely.” The world will see how successful DRM’s murderous plans are when the system launches at the 2003 World Radio Conference in Geneva. Radio may well be dead, long live radio.||**||

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