FM Reception Advice
The present DAB system delivers a large number of (often automated) services from the media conglomerates, in indifferent quality. It is impractical for the system to carry Local, Community, Hospital, University or Special Event stations. Britain is unique in having adopted DAB in a widespread way. Many believe developments have overtaken the system and it is not a technology which can survive in the long term.
A new and internationally agreed system has been developed, DAB Plus. Changeover in the UK has to be delayed for several years until the demise of legacy radios. By then other systems may have become the answer.
Finland closed down all of its DAB services in February 2005, while in Germany, MABB stopped issuing DAB licences in January 2005 on the grounds that `outdated` technology has been superseded.
In the Republic of Ireland the regulator, ComReg, has stated: 'It may therefore be prudent to leap-frog the Eureka 147 DAB system and implement newer technologies...', here.
In July 2005, CSA, the French regulator, published the results of their public consultation on digital radio, here. The four largest broadcasters, Radio France, NRJ, RTL and Lagardère, all reject the DAB system and outline alternatives. The paper from transmission provider, TDF, provides a technical overview and points out that newer systems are 10 times more efficient in the use of spectrum than DAB. Interestingly, one of the duties of Ofcom is to maximise spectral efficiency.
In October 2005, Kip Meek, Chief Policy Partner at Ofcom, stated "DAB is not the only digital radio technology" and outlined options in a speech here.
Despite investments in DAB of 400 million Kronor, in December 2005 the Minister for Culture announced a halt to further expansion in Sweden here.
As for the quality on digital: 'The 128 kbps bit rate for MP2 has been classified as "annoying". Unfortunately this is the bit rate that is most used by 98% of music stations on DAB in the UK!' - the full details are here. A technical paper covering digital audio quality by Dr. David Robinson, University of Essex Audio Research Laboratory, is here. BBC Research Department has constructed a piece of equipment which allows a person wearing headphones to switch instantly between the original audio and various types of digital coding. The degradations can be heard plainly.
The Ofcom Advertising Complaints Bulletin considered a Guardian Media Group advertisement which: 'to promote "DAB digital radio" referred to its provision of "CD-quality sound."' After taking evidence, Ofcom decided: 'We therefore believed the advertisement breached Section 2 Rule 3a (Misleadingness) of the Advertising and Sponsorship Code. The advertisement must not be broadcast again without amendment.' The full document from 2 August 2004 is here.
From David Hewson, writing in The Sunday Times, 5 June 2005: 'DAB radio is in the same sad state as ever. Like just about everything else in the digital audio field, it is technically and aesthetically inferior. DAB works by compressing audio - taking out bits and hoping we won't notice. It does this not using the old standard of MP3 but the even older one of MP2, and the results are dire.' The complete article is here.
Digital radio sound 'is worse than old FM' in The Daily Telegraph, January 2006, continued: 'Music lacked definition...', 'It's pretty nasty...'. The entire article is here.
The Radio Magazine reported former Capital Radio Chief Executive, Richard Eyre, calling DAB: 'a millstone' in August 2006, because: 'FM works a lot better since it actually passes through brick walls'. The article is here.
'So what's wrong with the technology?' 'The problem? Sound quality.' '...an old system with serious problems.' 'DAB gets a poor reception' in Media Guardian, October 2006, here.
In January 2007 The Radio Magazine reported that deficiencies were recognised: 'No DAB upgrade until 2013', here.
As the owners of Classic FM and Capital Radio closed DAB services in February 2008 they stated the future 'is on FM and broadband. FM remains the backbone of the radio industry and on quality compares favourably to any other platform', here. DAB 'the new Betamax', here.
Plans for a new DAB transmission network were put on ice and Ofcom permitted struggling operators to amalgamate in August 2008, here.
In October 2008 Channel 4 Radio axed plans for new DAB services, here.
'Digital Radio UK... will try to flog the UK's technically obsolete DAB... to a public that can't see the point, because good old-fashioned FM already works pretty well', by Jack Schofield in The Guardian, September 2009, here.
The VPRT in Germany state that 'FM is and will continue to be the most important means of transmission for radio', in January 2010, here.
Shambolic, outdated, unnecessary... My advice to anyone thinking about buying a DAB radio is don't, writes the CEO of a major UK radio operator in The Times, 12 July 2010, here.
Why digital radio is 'so difficult compared to digital television' is analysed in a pre White Paper Communications Review submission to the DCMS in September 2012, here.
In January 2013 the Public Service Council objected to DAB, wanting Sweden to follow Finland and abandon all plans to introduce DAB, here.
Research in October 2013's Journal of the Audio Engineering Society finds a bit rate "close to 300 kbit/s" is required to avoid falling below FM quality: DCMS submission Digital Radio - AES Research, here. Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems by Dan Nyberg et al, here. Summary of issues distinguishing digital radio from digital television: COMMUNICATIONS REVIEW - SEMINAR 5 - SUPPORTING GROWTH IN THE RADIO (AUDIO) SECTOR, September 2012, here.
The scale of the problem of digitally encoding audio in the same quality as the original analogue sound is illustrated below. Unlike coding moving images, where the eye is surprisingly forgiving of detail loss, the ear has remarkable acuity and ability to detect degradation in sound quality. The approximate bitrates required for unimpaired and good quality stereo are as follows:
Bitrates needed for original sound quality and statistical undetectability on any sound. Such rates are also needed to avoid concatenation errors when previously processed sound is tandem encoded further times:
MP2 at 512 kbps or higher
MP3 at 384 kbps or higher
AAC at 256 kbps or higher. 320kbps has been chosen for HD Sound by the BBC and Radio Jackie.
Bitrates needed for indistinguishable quality; i.e. good quality where people may hear a difference but cannot be sure which is best:
MP2 at 320 kbps
MP3 at 192 kbps
AAC at 128 kbps. BBC iPlayer uses 128kbps.
- The linear PCM WAV used on CDs is a bitrate of 1411kbps.
- MPEG-1/MPEG-2 Audio Layer II, MP2 used in DAB radio is between 48kbps and 192kbps (BBC Radio 3 only).
- MPEG-1/MPEG-2 Audio Layer III, MP3 and MPEG-2/MPEG-4, AAC are both widely used in podcasting and streaming.
We do not. Let me repeat this - we do not intend to switch off FM, stated the government's Culture Minister, Ed Vaizey, on 8 July 2010, here.
The moral of the story? If you buy a DAB set, make sure it also covers FM.
The long and short of it is that FM is an excellent system which is going to be around for very many years yet, so it is worth some effort to get the best out of your Hi-Fi and radios.
The power Jackie transmits with on 107.8 is regulated by Ofcom and, if you are any distance away from our transmitter at Tolworth Tower, reception will always be improved by attention to the aerial.
Avoid indoor antennas as they are subject to drifting performance as you move about the room and will pick up interference from thermostats, computers and other appliances.
Though you can try different positions for the arms, the ribbon T antenna that is packed with most Hi-Fi sets is grossly inadequate and will work with only the strongest local signals.
Any outdoor aerial will reduce interference and improve the signal strength vastly. Mounting the aerial horizontally provides some discrimination against interference (both pirate and electrical) which is predominantly vertically polarised.
A Halo picks up signals from all directions. Prone to interference and multipath echoes from hills or buildings spoiling the station you want.
A Dipole provides useful reduction of signals from unwanted directions since it has a figure of 8 pick up pattern. Maximum pick up is broadside, with nulls off the ends of the rods.
A 3 element Yagi, with Reflector and Director elements added to a Dipole, will improve reception quality noticeably.
Higher gain and better discrimination against unwanted signals arriving from other directions is provided by more elements.
A rotator and Triax FM8 at DX Radio (long distance radio)
If you wish to hear stations in markedly different directions, the ultimate answer is to add a rotator and these are not expensive nowadays.
Principles of operation: The Triax FM8 is a well engineered antenna. The folded Dipole towards the rear picks up the signal and is connected to the coaxial cable downlead via a balun, which couples between the symmetrical or balanced Dipole and the unbalanced coaxial cable. In terms of fractions of a wavelength, the first rod is very close to the Dipole and mainly serves to alter the feed impedance and broaden the bandwidth to cover the whole 87.5-108 MHz band. The next four rods act as Directors and, at the rear, there are twin Reflectors, which yield a slightly higher gain and front-to-back ratio than a single Reflector. Antenna theory dictates that gain is largely a function of boom length, so aerials with large numbers of elements in close proximity, like this, may look impressive but are never used by professionals.
Nine Triax FM8 aerials at Malmo/Skurup, Sweden.
If you are still not satisfied, you could aspire to one of these in your garden. This astonishing installation was once available for remote online listening.
Coaxial cable is needed to run down from the aerial and will probably need a Belling Lee coax plug fitting at the end.
There are amusing instructions on how to wire up these plugs here.
Radio Aerials and FM Reception Problems BBC Factsheets are here.
The Australian Broadcasting Commission covers Common Reception Problems here.
Television, radio and satellite reception advice from Aerial Services (London) Ltd is here.
ATV have advice for TV, DAB and FM aerials, along with photographs of cowboy installations, here.
The excellent Triax FM aerials and specifications are here (Products > Aerials > FM Aerials).
Three pages of Triax products are listed online by TV Aerials.com in New Romney, here, while a nearby Triax
and rotator supplier is AES Electrics, 54 Nutfield Road, Merstham, Surrey, RH1 3EP, Tel: 01737 643 767.
Maplin sell unbranded dipoles and halos here.
Brian Beezley has technical aerial comparisons and high performance FM receiver information here.
Paul Groves has frequency lists of stations you may hear all around the British Isles on both AM and FM here.
If you have 'a satisfactory aerial', Ofcom will investigate interference to broadcast services, here, and state: 'If the interference is caused by an outside source (such as an illegal radio transmission or faulty electrical apparatus), we will take appropriate action and will not charge you.'
CAR AERIALS and their performance - for both AM and FM, longer and higher is better.