I have earlier looked at Norway with it's very challenging topography and found that DAB is 20 times greener than FM. The mountains and valleys do however help digital coverage as the signals can bounce back and forth, making them stronger. The opposite is the case for analogue signals that are weakened or even killed in the case of reflections from mountains. There are few mountains in the UK.
I do not have inside knowledge about the transmitters in Britain, but the BBC is open about such matters and have made the info on transmitters publicly available on their website. Based on this, I have looked at all their FM and DAB transmitters listed there. The figures listed are however in ERP (effective radiated power), whereas the actual power usage is typically 2.5-10 times lower. Here are the figures (based on my own count, estimates and calculations):
FM, 99.8% coverage
Number of sites (towers/antennas): 395
Number of transmitters: 1,194
Wattage: 2,349kW
Average wattage per transmitter (not ERP): 1.97 kW
Increase in power needed due to amplifiers: 140%
Electricity used per year: 28,829,694 kWh
DAB, 86% coverage
Number of sites (towers/antennas): 231
Number of transmitters: 231
Wattage: 107 kW
Average wattage per transmitter (not ERP): 461W
Increase in power needed due to amplifiers: 400%
Electricity used per year: 3,736,836 kWh
The 1-6 radio stations transmitted via FM (based on coverage areas) does in other words use 7.7 times more electricity than the 11 radio stations transmitted via DAB. But the coverage of some of the FM channels are better than for DAB in certain areas, so we have to take that into account.
The current coverage of DAB is 86%, with 231 transmitters. It is always more costly to cover the last few percentages than the first, so let us assume that the BBC needs twice as many DAB receivers as today to cover 99.8% of the UK. That means 462 transmitters and sites. I'll even round that up to 500.
Based on the average wattage of the existing transmitters, we'll then get the following scenario:
DAB, 99.8% coverage (estimate)
Number of sites (towers/antennas): 500
Number of transmitters: 500
Wattage: 230 kW
Average wattage per transmitter (not ERP): 461W
Increase in power needed due to amplifiers: 400%
Electricity used per year: 8,088,390 kWh
With this estimate FM still consumes 3.6 times more electricity than DAB. Electricity prices in the UK are typically between 6.5 and 12 pence per kWh. Let us say that the BBC has managed to bargain on the price as they use a fair amount of juice. I have calculated electricity costs based on three different scenarios.
1) Great bargaining skills, paying an average throughout every day of the year of 5p per kWh.
2) OK bargaining skills, paying an average throughout every day of the year of 7.5 pence per kWh.
3) Poor bargaining skills, paying an average throughout every day of the year of 10p per kWh.
That gives us the following costs, in electricity alone, per year.
Scenario 1, 5p per kwH, 99.8% coverage
FM: 1,441,485 GBP a year
DAB: 404,420 GBP a year
Savings: 1 million GBP per year.
Scenario 2, 7.5p per kwH, 99.8% coverage
FM: 2,162,227 GBP a year
DAB: 606,629 GBP a year
Savings: 1.6 million GBP per year.
Scenario 3, 10p per kwH, 99.8% coverage
FM: 2,882,969 GBP a year
DAB: 808,839 GBP a year
Savings: 2 million GBP per year.
What's the damage?
BBC can in other words save approximately 1.6 million British pounds or 2.5 million USD a year, based on electricity costs alone in the least extreme scenario, if shutting off FM and transmitting only digitally. That is 74% less that what it costs for FM, in electricity that is.
Note that the numbers of transmitters are lower for DAB, whereas the number of sites are actually higher. This is the opposite of what is the case in Norway. Why is this? Topography plays a role, as mentioned above. But if you look at the transmitters you can also see a major power difference. Some of the FM transmitters are very powerful, the most powerful ones outputting 250 kW. The most powerful DAB transmitter does in comparison only output 10 kW.
FM can be shut off in 2015 if 50% of the listening in Britain happens digitally by 2013 (two years notice is required). You can in other words contribute to the BBC saving money (paid by you through the licence fee) on radio distribution and leave more money to quality programmes by listening to DAB instead of listening to FM. You will also help the environment and get a better selection of radio stations as a bonus.
Go green and help the BBC save your* money.
* Only applicable if you live in Britain and do pay the licence fee.
Also relevant:
DAB 20 Times Greener Than FM.
fascinating - have you sent them, UK news this???
ReplyDeleteA very interesting thought.. I've just been to a lecture in which this very subject was discussed. Food for thought. But will 50% of the UK ever go digital?
ReplyDeleteYou haven't, have you, confused Effective Radiated Power (ERP) with the actual output of the transmitter power amplifiers? The ERP will be several times the transmitter power, thanks to gain in the aerial array.
ReplyDeleteThe BBC seems happy to publish ERP figures for its transmitters, but the transmitter power itself seems much harder to find. So I worry that your figures are significantly higher than would actually be the case.
It works in terms of figures, how such a switch would work in practice is another mater. DAB is much derided here. Some of the biggest radio companies have largely withdrawn from it leaving lots of minority stations, it gets mocked for reception problems and attacked by audiophiles.
ReplyDeleteJust one quick correction:
The BBC only have 4 national networks on FM and a national MW station. Although you could count the local/regional stations as a 6th network the transmission of them is less efficient due to not being able to use a single frequency network. This is why they piggy back on commercial multiplexes.
This is part of the problem with converting totally over to DAB - local radio, especially to a very local level, is tricky to do. This is partially due to the way that they're licensed and the multiplexed nature of DAB.
Simon does make a good point, the power figures given are ERP, not what the actual transmitter is consuming from the grid (ERP includes aerial gain)
ReplyDeleteAlso it has to be considered that the BBC does no transmission itself. Arqiva transmit virtually every radio and TV service in the UK, the BBC isn't paying directly for that power. They pay a fixed term contract for everything and then Arqiva's outgoings are shared with their other customers.
Simon Blake is right - for example at Wrotham the ERP per service (R2-R4) is, from memory, 250kW but the Tx output powers are around 100kW. (R1 is lower on both counts due to frequency relationship with Air Navigation in frequency band above Band II.
ReplyDelete@Carmel:
ReplyDeleteI do believe that 50% of the UK will go digital. Digital also includes those who listen via web radio, cable TV and satellite TV. I do anyhow think that the British government will determine a switch off date no within 2-3 years, regardless of how high the percentage of digital listening is. Fewer and fewer people listen to FM, so the price per reached listener just continues to increase.
@Simon Blake, Stuart and bevm1066:
I have double checked the ERP issue now and corrected accordingly. Thanks for spotting! The ERP is typically 2,5-10 times higher than the effect of the transmitter itself. I have modified the calculations above, now using a factor of 8 which lowers the costs significantly.
Yes, Arqiva operates most sites for the BBC, but that will most likely just add to the bill, not lower it. And to run a network also includes much more than electricity.
DAB may have some reception issues in certain areas, but it has not been built to cover 99.8% of the population (yet) and DAB uses much much less power than FM radio transmitters.
When it comes to sound quality, you can find some audiophiles opposing DAB, others endorsing it.
Local radios may continue on FM even after the national radio stations go DAB only. And the equipment available now for a local radio station to transmit on DAB is now software based, something that makes it cheaper than FM equipment.
Actually, isn't Longwave the green transmission technology - after all who needs any other radio station than Radio 4? :-) 3 masts covers the entire UK and the receivers - like FM - require very little power for the listener to hear the programmes.
ReplyDeleteIt's the power consumption of a DAB receiver that kills any benefit from the lower transmission costs over FM, which I think are overstated here for reasons given above by Simon and others.
The good news is that the BBC has folk working on this question of making the business of broadcasting as green as possible, but it's not as easy as it might first seem.
@Richard:
ReplyDeleteOlder DAB receivers have problems with relatively high power consumption due to ineffective chipsets. This has now been resolved, and we see that modern DAB chipsets (25-60mW) have the same consumption as what is the case with FM (30-60mW).
You can even get solar powered DAB radios:
http://www.robertsradio.co.uk/Products/DAB_radios/solarDAB/index.htm
Ignoring at-home listening, what's the environmental impact of throwing away every in-car FM receiver and replacing them with DAB versions? Something tells me that sourcing all of the materials, turning them into a product and transporting them to consumers will offset the gains made by switching to digital transmission.
ReplyDelete@Chris Baume:
ReplyDeleteThis is a valid point. Although there are solutions and counter arguments. You can use a 12v powered adapter that receives the DAB signal and converts it to a very low powered FM signal that your existing radio can pick up. Or attach such a device to the antenna port of your radio.
The guarantee of a gadget is anyhow usually 2-5 years according to the purchasing act or similar legislation. If a gadget, i.e. an FM radio, stops working thereafter - well, most electronic retailers would tell you tough luck. If an FM switch off date is communicated to be in a few year, exisiting radios would have served their purpose for an more than adequate time before not working anymore. And even then, you can make it work again through a small and cheap DAB-FM dongle as mentioned above.
This is also a questions that is relevant to all kinds of products. Let's take mobile phones as an example. There are sold 2.4 million of those every year here in Norway. The average life expectancy is less than 18 months. Every year a mere 36,000 (1.5%) are recycled. Almost no people are complaining about that.
Consumerism is allowed, but of some reason not for radio. Why is that?
Re: Longwave
ReplyDeleteIt is true that LW and MW is more efficient in terms of covering a large area with fewer transmitters.... surely the BBC can go more green by using DRM for national broadcasting?
@Stuart:
ReplyDeleteTrue. The problems with DRM are that you can only fit in a very limited number of channels, that the channels can't be muxed together, that it wasn't made for additional services (traffic data, interactivity, breaking news, etc.) and that there are almost no receivers available anywhere in the world.
I tend to look at it another way.
ReplyDeleteWhether DAB is more efficient or not is rather irrelevant to me as a consumer because the sound quality in the UK is terrible compared to a good FM broadcast. This is because broadcasters routinely use less than the 192 kbit/s recommended for high quality audio by the BBC R&D team. Obviously there are good technical reasons why FM is less inefficient, but as a music lover I get a raw deal by switching the DAB.
I sold my expensive DAB tuner after 6 months because the music coming out of it was inferior in sound quality to FM, and not by a small amount. In the UK DAB is only really worthwhile IMO for kitchen radios where sound quality is not relevant.
In addition, most DAB radios are sold with an included FM radio, so they will never reach that magical 50% of the market.
However, what I think could be the final nail in the coffin is when consumers realise that they need to throw away DAB radios to have new DAB+ standards. Many, many radios are not upgradeable.
From a personal standpoint, DAB has been easily eclipsed at home by internet radio, Spotify and iPod usage. That's not a failing of DAB per se, but more a reflection of radio stations being out of touch with where the market is heading. My children never use a DAB radio, neither do any of their generation.
There is a big DAB lobby in the UK. It is called Pure and Roberts Radio. The rest of us hope it won't happen, because of the enormous cost of replacing radios (especially car radios) and the lower quality and spotty reception of DAB. It is fairly useless, and, contrary to what you think, does not propagate well in many UK conditions (including tall buildings). The energy argument is largely irrelevant as, contrary to what is said here, users are saying even the latest DAB radios are very power hungry.
ReplyDelete@Paul:
ReplyDeleteThe sound quality issue is like discussing taste in music. A lot of people do prefer the sound quality of DAB to that of FM. Although the kind of receiver you have is also relevant to sound quality. You have good DAB receivers, bad FM receivers and vice versa - and that is not necessarily related to the cost of the device. You are right that the bandwidth is also of relevance, but most major radio stations follow BBCs recommendations.
DAB+ is being used in some countries, including Germany, but not in Britain, Denmark and Norway.
@Wiltshire Hack:
You don't necessarily need to replace car radios, only add a 12V DAB to FM converter that will receive DAB and transmit a low powered FM signal.
The cost of replacing car radios is anyhow overestimated. Very few people complained about a similar issue when going from cassettes to CDs.
And colleagues of mine are currently testing various DAB and FM radios. Some older DAB radios are power hungry, but the new chipsets use the same amounts of power, or less, as FM receivers (20-60mW vs. 30-60mW).
"The sound quality issue is like discussing taste in music. A lot of people do prefer the sound quality of DAB to that of FM."
ReplyDeleteI disagree, it isn't like musical taste at all - it is measurable. I will accept that a lot of people prefer the lack of hiss on DAB, but anyone with a love of music will tell you that the broadcast quality is inferior. I was happy to move to CDs as the sound quality in my home was better, not so with DAB.
"but most major radio stations follow BBCs recommendations."
No they don't! Even the BBC broadcast below the recommended levels, which is why there were a ton of complaints last year. When I look at the DAB radio in my kitchen the bandwidth is typically 128 Kbit/s, sometimes 92 kbit/s, well below that necessary for the ancient MPEG2 CODEC to work well.
"The cost of replacing car radios is anyhow overestimated."
Most cars have built-in systems nowadays. A replacement radio for my car is close to £1,000 as a result. And I don't want a 12V adapter dangling around my car inviting thieves to break in and steal it, like they do with aftermarket SatNav systems.
Seriously, it's misleading and generalised comments from the industry that really annoy people. Please try to see it from the consumer point of view. DAB is not the future, not in its current form anyway. It's currently just a means for manufacturers to try to sell new technology, and they want us all to upgrade again in a few years time.
DAB may save on electricty, but it causes huge waste elsewhere.
I'd like to see how the 12V DAB-FM adapter will work in heavy traffic where the distance between cars is only a few meters. How can one then find an available frequency?
ReplyDeletePaul's comments are typical of that certain breed of dogmatic "anti" campaigner - sweeping personal statements masquerading as argument: "I don't like it and everyone else is idiot if they think differently to me." Paul is also factually incorrect, viz. there is no DAB bitrate of 92kbits (he means 96kbit/s). Factually, the majority of DAB listeners are happy with the quality. Ofcom (and others) have surveyed this issue and consistently show figures around 90% being happy with the quality of DAB. Those who have done laboratory controlled listening tests (have you Paul? Would you know a mushroom from a MUSHRA?) the evidence is that the design and make of MPEG encoder used by broadcasters can make a 20-30% difference in audio quality at a given bitrate. Expert listeners were unable to tell the difference between one reputable 192kbit/s codec and another 128kbit/s codec. Broadcasters could take more care here, but does the public care? Surely if quality was so dire, as Paul et.al. believe, then wouldn't people simply not buy DAB receivers, and wouldn't the retailers be sick of customers returning them? It seems not - the buying public like DAB. Fact: Over 12m receivers have been sold in the UK and over 40% of the population says they have listened to DAB. DAB accounts for more radio listening than any other digital platform by a factor of between 5 and 10. DAB listening is around 165million hours per week in the UK. These are figures of a successful broadcasting platform the public is embracing and loving. The real 'quality' issue here is whether DAB was ever intended to be a transcription service, i.e. indistinguishable from the original. Realistically this could never have happened - not enough spectrum and the basic economics of broadcasting - but the broadcasters didn't set expectations properly and the myth has continued. HiFi receiver listeners, the ones most likely to complain, amount to less than 1% of radio's audience. 99% listen on equipment where transcription quality is not the differentiator. Moreover, the vast majority of radio listening takes place in mono, a fact many broadcasters have recognised, electing to broadcast at 64, 80 or 96kbit/s in mono. There are alternatives for audiophiles - reception via satellite (256kbit/s) and the internet (BBC recently launched HD audio) - but for those who want portable and simple digital radio, DAB is fitting the bill, and by the million. During December 20,000 DAB radios were bought everyday.
ReplyDeleteGunnars' original point is entirely correct - DAB transmission is cheaper than equivalent FM and national broadcasters in particular are wasting money staying analogue. However, the savings are not confined to electricity. The other major cost of transmission is mast rental for the antennae. FM antennae are twice the size of DAB antennae, but often take up 4 or 8 times the mast space due to the ERPs being much higher. This translates into the cost of DAB mast rental at least half or a quarter of that necessary for FM. Furthermore, the space saving in the transmitter hall for a DAB transmitter (broadcasting multiple radio channels) compared with several separate FM racks is significant, reducing the site rental cost even more. When you add up these savings together with electricity, the BBC could reduce its transmission costs by much more than Gunnar suggests.
Good points, Marina! May I ask what background you have in order to have such in-depth knowledge about this?
ReplyDeleteCheaper for who? Broadcasters? Well it is expensive for the users. And the users decide the life of the broadcasters.
ReplyDeleteCheaper for broadcasters, but also cheaper for users in many ways. Users will get access to more channels, that means a lower price per channel. And when broadcasters save money on distribution they get more money to spend on programmes. That will benefit users too. They get better programmes and more choice.
ReplyDelete