Keeping radios working following analogue switch off.

[Jimmyhaflinger]

When you drive a car, you want a radio with a large display and conveniently placed controls (often on the steering wheel itself)

With an add-on DAB converter, you'll have to fiddle with the converter to tune in a station, as the original radio's tuning will only be needed to tune into the DAB converter's RF output.

That's not much better than playing a portable CD or MP3 through your tape player with a cassette adaptor.

I think most people are simply going to rip out the factory radio and replace it with a DAB one.

['LIVEWIRE?']

Originally Posted by Paul_RK

Interested to read as part of the response to a recent petition to halt AM/FM switch-off, "The Government is working with manufacturers to consider the implementation of a ‘set-top box’ solution for analogue radio which would allow existing analogue radios sets to receive DAB". As only a small proportion of existing radios offer an audio input facility, this seems necessarily to imply some manner of micro-transmitter. Unless of course it's just deflective waffle

Paul

I have read that government reply, and, to me, it's typical of such things- i.e. it makes the point the 'we, the government, have decided what's to be done, and there's an end to it. Makes the petition at best, of questionable value, doesn't it!

[M0AFJ, Tim]

Originally Posted by 'LIVEWIRE?'

I have read that government reply, and, to me, it's typical of such things- i.e. it makes the point the 'we, the government, have decided what's to be done, and there's an end to it. Makes the petition at best, of questionable value, doesn't it!

I liked the comment about handling the disposal of old sets via the WEEE directive..., I don't believe that there is enough capacity to recycle and reclaim in the whole of Europe let alone the UK, and if they decide to sell off the spectrum which is obviously what UK PLC would like to do what happens if the rest of Europe doesn't follow..., typical politicians.....

[kalee20]

Let's not make this into a moan against the politicians, because the mods will close what could be a useful thread.

I am watching to see if any manufacturer markets a set-top box. Probably this will be stereo FM - I can't really see a manufacturer making a MW AM one (although I wish they would, because if there were lots of these around, those of us who've made our own micropower short-range AM pantry transmitters would be even less likely to get picked up.

For the moment, this IS the only way to go. The up side is, that with a decent pantry transmitter, we can get better AM quality from our old sets than we'll have heard for a long time from 'official' broadcast transmissions!

[Phil G4SPZ]

Originally Posted by wireful3

...I do have a digital receiver but have difficulty deciding what I would wish to play through my analogue radios...

That is indeed a very good point. I play a selection of 1920s-1940s music through mine, and they sound much better reproducing authentic music of the era rather than modern offerings.

[G8HQP Dave]

The up side is, that with a decent pantry transmitter, we can get better AM quality from our old sets than we'll have heard for a long time from 'official' broadcast transmissions!

Sadly, this will be at the expense of worse FM quality than we currently get from some broadcast transmissions. Two reasons for this: a DAB rebroadcaster unit will never have as linear a modulator as the BBC can afford, and the DAB audio is already inferior to FM anyway.

I'm still not convinced that this will happen, at least not anytime soon. The 2015 date which was mentioned is likely to be an election year. Can you imagine a politician saying "Vote for me and I will switch off all your existing radios!"

[kalee20]

Originally Posted by Phil G4SPZ

I play a selection of 1920s-1940s music through mine, and they sound much better reproducing authentic music of the era rather than modern offerings.

Funny, I've heard 1920s-1940s music through contemporary hi-fi systems and it sounds better than modern offerings through this as well...

[flyingtech55]

Like earlier poster Graeme I too live in an area which is not covered by set-top box type signals. I don't receive DAB signals. What will I do when current signals are switched off? Like most things being currently done, provided services are available where most of the votes are, that does the job.

TimR

[chipp1968]

Hopefully they wont be switching them off . I cant see how they can when the digital signal is so hit and miss . I find VHF a pain allot of the time at work or driving to get a decent signal ,and thats been around 55 years !

[kalee20]

Originally Posted by G8HQP Dave

Sadly, this will be at the expense of worse FM quality than we currently get from some broadcast transmissions. Two reasons for this: a DAB rebroadcaster unit will never have as linear a modulator as the BBC can afford, and the DAB audio is already inferior to FM anyway.

Agree with the second point, but as for the first - although the modulator itself may not be particularly linear, negative feedback wrapped around the whole thing (via an FM discriminator fed from the RF output) can improve overall linearity.

[Hybrid tellies]

Using DAB to feed an AM low powered transmitter is fine but for FM I would use either a feed from Freeview, Satellite or cable where they use higher bit rates and so do sound closer in quality to FM broadcasts.

[G8HQP Dave]

Originally Posted by kalee20

Agree with the second point, but as for the first - although the modulator itself may not be particularly linear, negative feedback wrapped around the whole thing (via an FM discriminator fed from the RF output) can improve overall linearity.

Negative feedback will help, but you might need a discriminator which exactly matches the one in the FM radio! If done badly, it could make things worse.

[kalee20]

Originally Posted by G8HQP Dave

Negative feedback will help, but you might need a discriminator which exactly matches the one in the FM radio!

Definitely! Although if your current FM radio has a non-linear discriminator, then it'll sound mediocre with current broadcasts anyway. If you use the same discriminator characteristic to derive the negative feedback signal, then this radio will sound better than it's ever done, and your flagship, hi-fi-supa-linear-de-luxe radio will sound terrible!

[malvision]

Hi

The switch off will never happen on AM reason being too many stations.Think about all the third world countries who receive AM from a far ...who cannot afford local FM-AM transmitters etc. FM is limited in transmission range so SW and AM is here to stay maybe FM will die to DAB. but that's it.

[Antlong]

Hello all,

I had a quick play with a cheapo ipod transmitter intended for use in a car, less than a tenner from one of the foreign supermarkets. At very short range it seemed to work reasonably well but I couldn't see anywhere inside it which lent itself to a bit of RF amplification. Thinking about it it a bit more, I wonder if it was put in a well-screened box with lots of decoupling, could a bit of an internal aerial be amplified by a transisxxx valve on the outside to provide a slightly greater signal on VHF/FM stereo? A nice use for an acorn valve perhaps...

Regards Ant

[G8HQP Dave]

The audio quality of most of these is likely to be poor. Remember, they are sold on price mainly to youngsters who have never heard musicians play real instruments or real hi-fi - and may have been designed by such youngsters too!

A decent quality re-transmitter is likely to cost as much or more than a replacement radio, so is not a viable option even if the digital signal was good enough.

['LIVEWIRE?']

An idea occurred to me regarding AM radios. If a suitable MW micropower transmitter were available, which could be tuned to the frequencies once used by Caroline, 'Big L', etc(which in many areas will be free of modern UK stations)this could be fed from a CD player, playing recordings of sixties 'Pirate' radio, thus the program content and station announcements would be correct-i.e. 'Caroline on 199' would BE on 199m. Wouldn't be so easy to do this with BBC or Luxembourg recordings, since the frequencies are mostly still used for today's High Power Stations(unless, of course, these are switched off in 5 years time)

[Phil G4SPZ]

I already do something very similar. My micropower transmitter uses a 12AS7 and I prefer to transmit dance band music from the 1930s, which sounds exactly like it would have been heard by the wireless listeners of that period.

[PJL]

Radio broadcasting in the traditional sense would seem to have a limited lifespan. Streaming audio/video over the internet and Cellular Networks is the future whether we like it or not. Distributed connectivity over optical fibre making local connection via WiFi or Cellular offers huge advantage with unlimited 'stations' and the oppportunity to charge for it. I can easily see a scenario where there is no 'free' radio service.

[kalee20]

Originally Posted by Phil G4SPZ

My micropower transmitter uses a 12AS7

Should that be a 12SA7?