All posts by Trevor Harris
Below are all of Trevor Harris's postings, with the most recent are at the bottom of the page.
@Mark
Ed Vaizey is a politician he is in no position to say otherwise. My guess that in 2013 he will put off having to make a decision until he leaves his position in government.
The real problem comes when the BBC finds it cannot switchoff it's national FM stations. One solution would be to do as Portugal has done and that is just to switch off DAB. Most DAB receivers have an FM tuner in any case. The BBC could pay compensation which would be alot cheaper than keeping the costly DAB network going. Another alternative would be to do as Spain has done and reduce the coverage. Another solution would be to build a network based on DRM which would make FM and DAB redundent.
DAB has a spectral efficency of about 0.674 kbps/kHz. For DRM it is 1.91 kbps/khz about 2.8 times more efficient. DRM can also use the AAC codec which makes it even more efficient and so support 5 times the number of stations. AAC also supports surround sound which the BBC is developing. DRM is not a multiplex system which means that it is better suited to local radio and can be fitted into the FM white space.
Yet another advantage of DRM is that it works in the LW, MW and SW bands. Infact this is very attractive in that it only needs 2 transmitters for national coverage.
DAB is dead long live FM, LW, MW & SW.
| link to this comment |
Yes Steve P you are right the number of FM recievers is massive. Just about every mobile has an FM tuner. Most DAB radios have FM tuners so switching off DAB will have a minute impact compared to switching off FM.
I don't know about DRM+ being dead I just think it hasn't be born yet. As I pointed out it is about 5 times more spectrally efficient. The BBC experiment was very interesting. The interference mentioned by Mark comes from a Spanish station which reduces the night coverage on both AM and DRM. The BBC used a very low bitrate of 23kb/s inorder to keep within the mw channel limits.
Whether DRM will be a commercial success I just don't know. It certainly is technically far superia to the legacy DAB system.
Ofcom wants to sell off the FM white space and that would prevent it being used for DRM.
I notice Mark that you want choice but unfortunatly DAB will not do that. It will give you lots of stations but they all sound the same. The reason is that most of them are run by large broadcasting companies. Ofcom has failed to deliver the variety that independent stations can bring. The automatic renewing of FM licences has not helped. That is why there are so many pirate stations which have quite large audiances. They often specialize in a particular gendre of music. The other problem is that DAB is too expensive. Not a single DAB only station makes a profit.
| link to this comment |
Very interesting.
I did a quick check and found that from the Guildford transmitter the the signal strenth was greater for London 3 than London 1 when the opposite should be true.
I live in the Guildford area and looking at these maps shows how poor the coverage still is. You cannot go into a shop and buy a DAB radio and know that it will work.
It has been estimated that it will take a total of 1000 transmitters to provide the 99% coverage. When I look at these maps I wonder if that is not an underestimate. Dorset has very little coverage. Up to now the BBC has been able to cosite transmitters with existing FM transmitters. To fill in all the white space they are going to have to buy new sites which is going to increase the costs even further. On a previous post I estimated the cost of going to 99% but I had based this on previous costings. Clearly this would be an under estimate. In the end the DAB national multiplexes are going to cost many times the cost of the existing FM network.
As the BBC has admitted it is not yet known if it is technically possible to reach Ofcoms 99% target. I do feel that the BBC should have done this study before embarking on this white elephant.
Looking at this map shows how poor the comercial DAB coverage is. As I have said before no DAB only radio station is makeing a profit and will eventually disappear.
| link to this comment |
@Brianist
The use of mobile masts is interesting but I would have thought they are not tall enough as cells are actually quite small. The Guildford masts are quite alot taller than most mobile masts.
| link to this comment |
@Mark
I would point out that the BBC had to go 230 to 404 in order to increase coverage from 93.8% to 97.2%. So it took a 75% increase in transmitters to go increase coverage by 3.4%. Even if we don't alow for deminished returns we will need roughly a 50% increase to go an extra 2%. That is 606 transmitters in total. Looking at the maps you can see that the gaps in the coverage will be very difficult to fill. Every motorway near me has long stretches not covered. The other issue is that the 99% coverage is an average and some regions will have much poorer coverage as shown by the BBC appendix to Ofcoms document.
It is interesting to note that the BBC is researching into DVB-T2 lite for use in car radios. So may be even the BBC realises it needs a plan B for when DAB fails.
| link to this comment |
The difference is money. I read recently that the BBC spends over £4000 per hour for some of its radio 4 programs. Its only the forced licence that makes it impossible for anyone else to compete.
| link to this comment |
So we see yet another desparate attempt to make DAB pay by lowering the quality yet again.
Why the name MountainFM when this station does not transmit on FM. Is it trying to convey that it attains the quality of a real FM station.
No DAB only radio station makes a profit. Looking at the web site we read.
Mountain FM is supported by Coalfields Regeneration Trust. The project has been part funded by the EU's Convergence European Regional Development Fund through the Welsh Assembly Government.
Which explains how Mountain FM can afford to transmit on DAB. Of course what they realy need is an FM frequency.
| link to this comment |
@Mark
Absolute 80s is part of the Absolute group and to quote:
Pre-tax losses of £2.7m in 2008 slipped to £4.3m in recession-ravaged 2009. Official figures for 2010 will not be available until the fourth quarter but are expected to remain in the red, despite a marked recovery.
A report in the Times last December quoted the chief executive:
The company is on track to break even in 2011, despite the tough times with the economy,
This he hopes to do with other ventures like concerts and special events.
Advertizing revenues for commercial stations has been declining since 2004. The Government cut backs alone will reduce. revenues by 9%.
| link to this comment |
Sorry the report in the Times was for Jazz FM.
@Nedbod
The Worldservice is available on the internet at 64kb/s AAC. There are going to be realy big cuts in WS when the BBC has to pay for them.
| link to this comment |
Tuesday 19 July 2011 1:57PM
Now digital have only promised to build one transmitter now in the Barnstable area, They have promised to build the other 2 six months after a positive decision in 2013 by Government regarding digital switchover. In other words never.
The corrupt method of bribing commercial stations to build DAB stations in exchange for FM licences is immoral. It prevents new stations gaining licences and it prevents the public from having any say about what stations they want in there area.