Radio - DAB v FM v the alternatives

Capt'n Midnight

Sam Russell wrote: »

The sales of DAB radios are given as the evidence for the popular demand for DAB, not the number who actually tune in.

Given that practically every DAB radio can receive FM those sales figures are meaningless. And they include stuff like car radios where the consumer doesn't have a choice. It's a safe bet that people buying DAB capable receivers outside of the coverage areas aren't using them for DAB.

It's as valid as counting every smartphone , digital terrestrial and satellite receivers as non-DAB radios. (Freesat means series link on Radio 4) And that's before you include streaming. You'd also have to include the majority of DAB radios in the total since they can receive FM too.

Capt'n Midnight

The Spare Bowler wrote: »

I have been listening to RTE radio on DAB in Dublin for a number of years now, the reception is perfect on both DAB/DAB+. There is about 15 stations with a good selection, every part of the country should be able to get the same service as we have in Dublin. People who say that there is no future for DAB/DAB+ are wrong, we must make better use of the spectrum for national and local radio. Just like television which is now all digital, radio must go the same route.

The Spare Bowler wrote: »

I have been listening to RTE radio on DAB in Dublin for a number of years now, the reception is perfect on both DAB/DAB+. There is about 15 stations with a good selection, every part of the country should be able to get the same service as we have in Dublin. People who say that there is no future for DAB/DAB+ are wrong, we must make better use of the spectrum for national and local radio. Just like television which is now all digital, radio must go the same route.

radio must go the same route

WHY ?

Digital TV is a no-brainer. There's a massive improvement in quality. I'm still amazed at how HD looks compared to the fuzzy pictures on ye olde black and white portable. Huge savings in transmitted power, virtually eliminated multi path and co-channel interference. Look at the UK to see the huge numbers of extra channels that can fit on the band.

DAB on the other hand isn't saving any transmitter power, doesn't use less bandwidth, unless you drop the bit rate way down. Pretty sure there's 15 FM stations in Dublin too. Like mobile phones of course there'll be coverage in the densely populated areas. And like mobile phones the issue is coverage in the back of beyond.


Unlike DAB , most FM smartphones / pocket radios use a 75cm headphone cable as a quarter wavelength antenna on the FM band. ( A tiger tail might improve FM reception )

Sam Russell

FM was the forerunner to digital.

It gave pure, noise free, reception while AM gave noise and distortion even in strong signal areas, and AM was subject to terrible interference for lawnmowers and motorcycles (they now have suppressors on the ignition). FM was immune to all these travails and fostered the BBC Third Programme that meant the BBC was able to broadcast high quality classical music that the purists could appreciate without complaint. FM has improved on that 1950s performance with many improvement granted by modern electronics.

DAB does not improve on the FM level of performance without using huge bandwidth (compared to current norms on DAB) and will not get the required bandwidth for top rate sound quality.

Who wants DAB? (Actually who considers it to be an improvement on FM).

Thurston?

Sam Russell wrote: »

Well, FM is sort of digital and sort of analogue ... It does suffer a 'digital cliff' effect

It is not anyway digital.

Your cliff effect is purely down to limiter circuitry in the receiver: if amplitude is conveying no information, then simply block everything below a certain amplitude, & get rid of co-channel (or near-adjacent) interferers, that will obviously be weaker in a properly planned network.

Sam Russell

Thurston? wrote: »

It is not anyway digital.

Your cliff effect is purely down to limiter circuitry in the receiver: if amplitude is conveying no information, then simply block everything below a certain amplitude, & get rid of co-channel (or near-adjacent) interferers, that will obviously be weaker in a properly planned network.

I did not say it was a digital signal.

It does behave somewhat like a digital signal in that it can reject significant interference, and it does suffer from sudden failure in low signal, while being robust above this level. It delivers good signal to noise performance.

There has been significant improvements in circuitry in the last 60 years which has improved its performance.

Hotblack Desiato

Where can I get the DAB shower radio for a tenner that gives perfect reception on a small trailing wire antenna and runs for months on two AA batteries?

Nowhere, that's where!

The only advantage of DAB is the ability to cram more channels in than FM can, but at least in the Irish market that's pointless. The FM band even in Dublin is not saturated with viable PSB and commercial stations - there is still room in the band for pirates, and TXFM is going to close down. Niche stations cannot survive on FM as it is. Their cost of transmission on DAB will be higher and there is not enough advertising budget to go around, or content...

Sam Russell

Hotblack Desiato wrote: »

Where can I get the DAB shower radio for a tenner that gives perfect reception on a small trailing wire antenna and runs for months on two AA batteries?

Nowhere, that's where!

The only advantage of DAB is the ability to cram more channels in than FM can, but at least in the Irish market that's pointless. The FM band even in Dublin is not saturated with viable PSB and commercial stations - there is still room in the band for pirates, and TXFM is going to close down. Niche stations cannot survive on FM as it is. Their cost of transmission on DAB will be higher and there is not enough advertising budget to go around, or content...

DAB has significant advantage - it uses band III that has been vacated by TV (although we still reserve a mux for Saorview should we require it). That allows DCERNR to sell bandwidth. Other than that - not so useful.

FM should be good for another 30 years - we have had it for 60 years so far.

The Cush

Hotblack Desiato wrote: »

Niche stations cannot survive on FM as it is. Their cost of transmission on DAB will be higher and there is not enough advertising budget to go around, or content...

This is where ‘small scale DAB’ multiplexes (DAB mini-muxes) come in, using a new approach developed by Ofcom, allows local and community radio stations to transmit on DAB for a fraction of the cost of current DAB multiplexes.

A small scale DAB trial is underway in the UK, ten short-term trial licences were awarded last year and all are now broadcasting.

The Niocast Digital mux in Manchester was to have carried RTÉ Radio 1 since last Autumn but hasn't happened yet, someone in another thread mentioned licencing issues.

http://licensing.ofcom.org.uk/radio-broadcast-licensing/digital-radio/mux-licensing/small-scale-trial-multiplex-licensing/

Thurston?

Hotblack Desiato wrote: »

The only advantage of DAB is the ability to cram more channels in than FM ...

What about resistance to multipath? I can't be the only one who's driven into a parking space, only to have the channel I'm listening to disappear ... & then fade in & out as people walk past. And then reverse back a foot or two & it returns ...

Antenna

Thurston? wrote: »

What about resistance to multipath? I can't be the only one who's driven into a parking space, only to have the channel I'm listening to disappear ... & then fade in & out as people walk past. And then reverse back a foot or two & it returns ...

This effect is more noticeable with cars which increasingly have the FM aerial printed on the rear window (with the demister) rather than a car roof aerial. There can be significant reception nulls off the sides of the car, and reflections as you describe will be more noticeable.

Sam Russell

Antenna wrote: »

This effect is more noticeable with cars which increasingly have the FM aerial printed on the rear window (with the demister) rather than a car roof aerial. There can be significant reception nulls off the sides of the car, and reflections as you describe will be more noticeable.

Surely that effect would be worse with DAB than with FM given the shorter wavelength.

Also, do we not use vertical polarisation for FM? - and so a printed horizontal aerial would have problems.

TAFKAlawhec

Digifriendly wrote: »

I have experienced digital radio here in NI for quite a number of years now but rarely listen to digital stations on the one DAB radio in our house. I listen more to my analogue FM/MW radio and to digital only radio stations on Freeview/Sky. The ASO date for radio in UK keeps getting put back and back and even my present car which I bought only last year has an analogue radio. I get the feeling that DAB has not really taken off in the UK since it was first introduced and people are generally happy to listen to FM/MW most of the time and if they want to listen to digital only stations they either listen through their TV or the internet. BTW I listen also to RTE stations via Saorview or main stations via FM for the FM signal where I live is excellent.

There's never been any formal ASO for analogue radio in the UK, only some fanciful ideas by commercial group executives whom would prefer to reduce costs on parallel transmission infrastructure. Also the majority of new cars sold in the UK now have DAB+ receivers as standard, it's mostly cheaper models where FM/AM only radios are still commonly seen.

DAB was very slow to take up in the UK for multitudes of reasons, but in the last few years it's steadied the ship to an extent. The cost of DAB radios has now gone below £20, battery life is much better than it used to be (though still a bit to go to match analogue power) and BBC 6 Music & Absolute 80's are the main DAB success stories with over a million listeners each. There have been recent works to reconfigure frequencies in England recently to help improve coverage of local multiplexes, while in London DAB is more popular than elsewhere in the country as it helps alleviate issues concerning interference from pirate stations in the FM band.

I haven't got the latest breakdown of figures, but the percentage of people who listen to digital radio via their television is quite small from what I remember - it's handy in some circumstances but for most people it isn't a preferred option.

Thurston?

Sam Russell wrote: »

Surely that effect would be worse with DAB than with FM given the shorter wavelength.

DAB is a COFDM signal in a channel about 1.5 MHz wide. The multiple carriers across this channel width aren't going to be equally affected by fading.

Hotblack Desiato

Sam Russell wrote: »

DAB has significant advantage - it uses band III that has been vacated by TV (although we still reserve a mux for Saorview should we require it). That allows DCERNR to sell bandwidth. Other than that - not so useful.

No point lighting up band III to duplicate what we already have in band II. There is no better alternative use for band II I'm aware of instead of broadcast FM, so it's not going to be sold. There is no indication of a need for more commercial stations than can fit in the FM band. RTE Gold / Chill etc can't justify DAB on their own.

The Cush wrote: »

This is where ‘small scale DAB’ multiplexes (DAB mini-muxes) come in, using a new approach developed by Ofcom, allows local and community radio stations to transmit on DAB for a fraction of the cost of current DAB multiplexes.

Cheaper than low power FM?

Again we're back to the lack of viable content and how to fund it. DAB makes more content physically possible, it doesn't make more content financially viable (even ignoring the transmission costs issue.)

Thurston? wrote: »

What about resistance to multipath? I can't be the only one who's driven into a parking space, only to have the channel I'm listening to disappear ... & then fade in & out as people walk past. And then reverse back a foot or two & it returns ...

Not much of a use case really, though, is it?

Sam Russell

Thurston? wrote: »

DAB is a COFDM signal in a channel about 1.5 MHz wide. The multiple carriers across this channel width aren't going to be equally affected by fading.

Get a better car aerial - vertically polarised.

Antenna

Sam Russell wrote: »

Surely that effect would be worse with DAB than with FM given the shorter wavelength.

Also, do we not use vertical polarisation for FM? - and so a printed horizontal aerial would have problems.

The FM aerials on the rear window demister is a line going from top to bottom of the window, either one or two of them depending on the car, so it is slanted - more vertical than horizontal.
As I said some cars have two FM aerials on the rear window and the radio selects which one is giving the better signal.
However a roof aerial will give the best reception and is less likely to be affected by interference from the increasing amount of electronics in modern cars (which would be worse at Band II than Band III)

The Cush wrote: »

A small scale DAB trial is underway in the UK, ten short-term trial licences were awarded last year and all are now broadcasting.

There is a lot of comment about poor coverage of these trials within the intended areas, with poor building penetration etc compared to the regular DAB services, they would all need fairly substantial power increases (if feasible) to make any impact with the majority of DAB listeners.

SimonMaher

I am as always surprised in these debates to hear people discussing DAB as a replacement for FM. I don't see DAB(+) ever replacing FM here, nor should it. FM is a simple, proven technology and long may it reign!

Now, DAB can have it's place too - as a complimentary platform. We tend to obsess about the technologies and the demands from the general public/lack of demand and we get caught up in that. Let's face it though, all that matters is content and that's the way it should be. If you can provide content that people want to listen to, then get it on as many platforms as you can. If it's good, people will listen. If it's not, they won't.

Don't worry about the nonsense of Commercial radio not wanting to get on board with DAB. If they see content getting listeners on any platform then they will follow, you can be sure of that. Licence DAB, see will people take on the operation of the Multiplex (they will!), see can they sell space to content providers (that's for them to figure out) and if it works, then grand. If it doesn't, what's the harm in trying?

Simon

Thurston?

Sam Russell wrote: »

Get a better car aerial - vertically polarised.

My car aerial is on the roof, & anyway, most of 2RN's FM transmitting aerials are mixed polarisation, & I'd be pretty sure that's also the case with the UK stations I can receive. (Good reception, near the border.)

The Cush

Antenna wrote: »

There is a lot of comment about poor coverage of these trials within the intended areas, with poor building penetration etc compared to the regular DAB services, they would all need fairly substantial power increases (if feasible) to make any impact with the majority of DAB listeners.

Read similar alright, this is a small indefinite Ofcom trial after all where issues relating to this type of mux can be investigated and resolved before formal licences are eventually issued.

Mickey Mike

Sam Russell wrote: »

They did some self help schemes for analogue TV in the day - I wonder would they try something like that again? Self help allows the locals to provide the site and 2RN provide the equipment which would be very low power stuff as it is a very local fill-in service plus it is old hat technology.

Speaking of sites, RTE own a very large number of these sites all over the country. Most of them abandoned after TV ASO, I still see the mast standing in Listowel and Abbeyfeale and no doubt all over the place. But its the will to do it, maybe with the closer of LW 252 and maybe the scraping of DAB we'll get one format right at least, A top of the range FM service.

marno21

Mickie Mike wrote: »

Speaking of sites, RTE own a very large number of these sites all over the country. Most of them abandoned after TV ASO, I still see the mast standing in Listowel and Abbeyfeale and no doubt all over the place. But its the will to do it, maybe with the closer of LW 252 and maybe the scraping of DAB we'll get one format right at least, A top of the range FM service.

Both of these sites have FM allocations

Listowel: 89.3/91.5/93.7/98.9
Abbeyfeale: 88.3/90.5/92.7/97.9

Listowel was never activated as Knockanore is used instead on 89.2/91.4/93.6/98.7/101.0

Abbeyfeale could do with a TX for the town centre alright. The Abbeyfeale TX is used for FM at present, it carries Spin South West on 103.9

Sam Russell

Mickie Mike wrote: »

Speaking of sites, RTE own a very large number of these sites all over the country. Most of them abandoned after TV ASO, I still see the mast standing in Listowel and Abbeyfeale and no doubt all over the place. But its the will to do it, maybe with the closer of LW 252 and maybe the scraping of DAB we'll get one format right at least, A top of the range FM service.

If only - if only.

RTE are astonishing in the extent they go to disappoint.

Mickey Mike

marno21 wrote: »

Both of these sites have FM allocations

Listowel: 89.3/91.5/93.7/98.9
Abbeyfeale: 88.3/90.5/92.7/97.9

Listowel was never activated as Knockanore is used instead on 89.2/91.4/93.6/98.7/101.0

Abbeyfeale could do with a TX for the town centre alright. The Abbeyfeale TX is used for FM at present, it carries Spin South West on 103.9

Very true, good signal in Listowel, Abbeyfeale not as good , so its things like that that needs improving. West Limerick 102 is gone from Abbeyfeale used to be on 101.4 Is that the same tx as Spin?

marno21

Mickie Mike wrote: »

Very true, good signal in Listowel, Abbeyfeale not as good , so its things like that that needs improving. West Limerick 102 is gone from Abbeyfeale used to be on 101.4 Is that the same tx as Spin?

Yep, coverage of the national stations in Abbeyfeale and up the N21 as far as Barnagh is very poor.

I'm not sure where that West Limerick 102 came from but I'd imagine it was the same site. RTE could do with activating FM from there instead of rolling out DAB. The money spent would mean duplication of services to many areas yet DAB would do nothing for places like Abbeyfeale (and tens of other small towns and villages)

STB.

SimonMaher wrote: »

Don't worry about the nonsense of Commercial radio not wanting to get on board with DAB. If they see content getting listeners on any platform then they will follow, you can be sure of that. Licence DAB, see will people take on the operation of the Multiplex (they will!), see can they sell space to content providers (that's for them to figure out) and if it works, then grand. If it doesn't, what's the harm in trying?

Simon

They have been the biggest objectors though Simon. Its alll about keeping what you have.

Dusty in Dublin and Andy Linton in the South East were the only ones who were ever interested commercially that they trialed it.

I don't want to see it either. Sure you'd have nowhere to test your rig.

SimonMaher

STB. wrote: »

They have been the biggest objectors though Simon. Its alll about keeping what you have.

Dusty in Dublin and Andy Linton in the South East were the only ones who were ever interested commercially that they trialed it.

I don't want to see it either. Sure you'd have nowhere to test your rig.

Agree that they are the biggest objectors of course! Protectionism has always been to the fore and bizzarely continues to be, despite the fact that the world of radio is changing and those objecting operators have more to be worrying about.

Nobody has ever been given the opportunity to provide a permanent licenced DAB MUX in Ireland. RTE, Dusty, Total Broadcast et al have taken a punt at it themselves but none of them have a permanent MUX licence because none has ever been advertised/tendered/offered. Can't build a business around that. Nobody is going to invest their hard earned in promoting a station on a platform that could be switched off tomorrow.

As I've said before, it's not a replacement medium, it's a complementary medium. So, you could have FM104 Gold on it just as easily as you could have Zenith or 8Radio or whatever.

Build it and they will come There will always be somewhere to test your rig!

Simon

former total

But if the existing commercial operators don't want it, who is going to make the initial investment and then run the stations? And how would they recoup their money?

There simply isn't enough advertising money out there to support two rival platforms, especially since streaming and internet radio are taking bigger chunks out of the broadcast audience year by year.

Mickey Mike

Moves are beginning to take shape around Europe shortly with regards to FM switch off. UK no fixed date, Norway, Switzerland and Germany. Germany currently migrating to DAB+. But that's fine where there is big population, we are too small and quite a few stations are only breaking even. Its money money money, we have our FM so we'll be grand.

Sam Russell

If we say no to Dab and keep FM, we will affect few as we are on the edge of Europe - only UK is within reach, and not much of that anyway. We should use band III for TV as it will have better reach than Band V, so fewer transmitters and so could be used for 'local' TV.

The Cush

Sam Russell wrote: »

We should use band III for TV as it will have better reach than Band V, so fewer transmitters and so could be used for 'local' TV.

Won't be happening according to RTÉ

RTÉ believes that VHF spectrum is not a viable alternative for even current digital terrestrial television requirements. It would require an entirely new broadcast network, replacement antennas for all viewers, and a reduced amount of content with no facility for further development. Furthermore, there are no viable alternative or converged technology solutions that can deliver public service free-to-air digital terrestrial television comparable to DVB technology likely to emerge in the medium term.