26 MHz DRM Broadcasts for London

WRN intends to broadcast Stereo Digital Radio to London on 26 MHz. The DRM consortium http://www.drm.org/ have for some time floated the idea of using 26 MHz to provide groundwave coverage of cities. I believe this will be the first time anywhere in the world that someone has actually tried it out.

The members of the DRM consortium are trying to find additional frequencies to use for DRM. If the London transmissions are successful we can expect to see greater use of 26 MHz for broadcast transmitters serving a local area probably with a coverage radius of 20 miles.

26 MHz is midway between our 24 and 28 MHz bands. IF this band became popular for local broadcast station use and IF large numbers of consumer radios incorporating 26 MHz DRM were sold it might have an impact on Amateur operations. (Amateur Tx may overloaded consumer drm rx front-end). Fortunately there are two "ifs" there, however, it'll be worth keeping an eye on this trial.

73 Trevor M5AKA
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Press release Issued by WRN
London, 2nd September 2005

WRN unveils its DRM projects including innovative local test broadcasts for London on 26MHz

WRN, the London-based international transmission service company, today announces its plans for broadcasts to London and Europe using DRM (Digital Radio Mondiale), the digital AM radio system with near-FM quality sound. The first project will test transmission of DRM at 26MHz in London whilst the second project offers broadcasters European regional DRM coverage.

London DRM

WRN's test and development project for London will assess the potential coverage of DRM transmissions at 26MHz. It will provide important data on the penetration of the signals into various types of building and other urban situations as well as gauge audience reaction to the broadcasts. WRN will create a full test and development schedule for submission to Ofcom and the DRM Consortium.

The transmission site is the world famous Croydon broadcast tower, situated in South London and operated by Arqiva (formerly NTL Broadcast), WRN's DRM transmission partner for this project. Arqiva provides transmission services for most UK commercial radio stations.
Croatia's RIZ-Transmitters has supplied the Yagi antenna and transmitter for the duration of the project.

Tim Ashburner, WRN's Technical Director says: "The London analogue spectrum is unable to support new FM services and the possibilities for more stations on DAB Digital Radio are becoming very limited. The audio quality of analogue AM is not up to the standard that is expected by listeners today. The answer may be local DRM services using the presently unused 26 MHz band, which could support up to 50 new stereo radio services. This project will allow us to rigorously test DRM in a local setting using one of the most ethnically diverse, cosmopolitan and technically challenging cities in the world. If it works in London then local DRM can work anywhere."

European Regional DRM

WRN's regional DRM service offers broadcasters comprehensive coverage of Europe using DRM sky-wave transmission and directional antennas.
Furthermore, the service can be used to  each specific key target areas with frequencies that provide higher reliability in urban areas from the transmitter site located in South East Europe. Telefunken has supplied the modulator and exciter for the service.

Gary Edgerton, WRN's Managing Director says, "DRM offers FM and stereo audio quality on the bands up to those now used by AM stations and it will revitalise these bands for local, national, regional and international broadcasting. We are inviting broadcasters to discuss with us their participation in all aspects of our DRM projects and to be part of the revitalisation of international broadcasting."

WRN will encode both DRM services at its central London headquarters, providing the flexibility to generate a pre-mixed DRM stream that will then be fed to the respective transmitter sites. WRN will also add data for receiver display utilising custom created software.

- Ends -

For more information contact:

Tim Ayris, Marketing Manager, WRN:
E-mail: tim.ayris@wrn.org

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Ok, I give up. What is DRM? And what is MONDAILE? Sorry, I live in the stix, and am the last to know.

TOM K8ERV Montrose Colo

 

DRM stands for Digital Radio Mondiale. IIRC, Mondiale is an adjective form of the word for "world" in some Latin-derived language, so "digital radio for the world".

It is a digital radio protocol for AM and shortwave bands. It is supposed to have "near FM quality audio" in a regular 9 or 10 khz AM radio channel. Because it is digital, it is supposed to be resistant to the noise that you usually hear on shortwave.

For the purposes of this discussion, exactly what it is isn't so important as the speculation that there may be interference problems because somebody wants to use it near existing amateur bands. This concern would apply to any service on those frequencies, not just DRM.

 

May I suggest 26.985 MHz as a good starting frequency?

 

Nah, start at 26965 KHz and give DRM oh, say 40 channels on a 10 KHz raster

Hmmm...they resally need to add an :Evil smilie



73 DE KAØGKT/7

-- Steve

 

Not interested in SWL.

TOM K8ERV Montrose Colo

 

Gee Tom, I dunt know either.
but then I live in the Stick.
it's so desolet here we only got one.
not like you rich guys who live in the sticks.......

 

Evil smile...

 

that bothes me.
then where would the pirates go??

 

Geeze ur guise are great. The pix made mie day-- or weak--

TOM K8ERV Montrose Colo

 

I have my reservations about DRM

Here in the UK we have recently been granted an extra 100khz on 40 metres so the band now extends from 7000 to 7200khz. There is a DRM station (Luxembourg I think) on 7145khz ( this part of the band is 'shared' with BC ). This wipes out a good part of the 7100-7200 part of 40m when the skip is short as it seems to be very wide. I haven't done any exact measurements but it seems a whole lot wider than 'normal' AM.

Wonder if you guys in the US hear it & what do you think about it?

73 de Peter.

 

Do you need a DRM receiver to pick it up? I think that the only real way we could get it is if it were compatable with the digital modes that we've got here like Sirius or XM.

Okay, I rechecked the link. They're saying that this isn't proprietary, but you still need to buy a specialized receiver or Download specialized software.

 

just in case you'd like to know more:

DRM: Technical Aspects of The On-Air System

DRM is the world's only, non-proprietary digital radio system for short-wave, AM/medium-wave and long-wave. It has been endorsed by the ITU, IEC and ETSI. While DRM currently covers the broadcasting bands below 30 MHz, the DRM consortium voted in March 2005 to begin the process of extending the system to the broadcasting bands up to 120 MHz. The design, development and testing phases are expected to be completed by 2007-2009.

DRM is the only universal, non-proprietary digital AM radio system with near-FM quality sound available to markets worldwide.

The quality of DRM audio is excellent, and the improvement upon analogue AM is immediately noticeable. DRM can be used for a range of audio content, including multi-lingual speech and music.

Besides providing near-FM quality audio, the DRM system has the capacity to integrate data and text. This additional content can be displayed on DRM receivers to enhance the listening experience.

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 9 kHz or10kHz 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.

Simulcast testing is underway.

Many existing AM transmitters can be easily modified to carry DRM signals.

DRM applications will include fixed and portable radios, car receivers, software receivers and PDAs. Several early prototype DRM receivers have been produced, including a software receiver. 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 DRM 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.

The robustness of the DRM signal can be chosen to match different propagation conditions.

I think I'd rather go Fishing...


Magnus Oskar Asbjornsen 1921-1993