Medium Wave Transmissions

[D Cassidy]

Hello.
I wonder if anyone can confirm or otherwise if it's correct that a fair number of European Medium Wave stations will be turned off before the end of the year. A local Radio Amateur friend told me this some weeks ago but I don't know how to find out if this is correct.

[G6Tanuki]

It's been going on for years: none of the major players [whether State-funded or independent/commercial] have considered MW/LW listeners a major audience-segment for at least the last decade.

[paulsherwin]

Yes, it's an ongoing process. A number of legendary transmitters have already gone including Beromunster (Switzerland) and Athlone/Tullamore (Ireland), all in 2008.

['LIVEWIRE?']

Not that I'm a regular listener to the following stations, but presumably Radio 5 Live, Talksport, Absolute Radio, and Radio Wales will continue on MW for some time yet. BTW, RTE Radio1 is, AFAIK, still on 252kHz LW.

[paulsherwin]

There are no immediate plans to close the UK AM transmitters, though RTE1 is already on borrowed time and is likely to close once RTE work out how to satisfy the political demand for a service for the Irish in Britain (probably a low bitrate DAB or Freeview channel).

[Hybrid tellies]

At the end of the year the main German broadcaster DLF is closing its remaining Medium wave transmitters on 549Khz, 756Khz, 1269Khz, and 1422Khz. Luxembourg on 1440Khz is also going together with the France Info and Bleu AM network on 603Khz, 711Khz, 864Khz, 1206Khz, 1242Khz, 1278Khz, 1377Khz, 1404Khz, 1494Khz and 1557Khz. All these stations can be received clearly after dusk so the Medium wave band is going to be a lot quieter after dark in the new year.

[D Cassidy]

Hello Simon.
You have confirmed then what I have been told. Certainly Medium Wave is so much quieter than it was twenty years ago. I've had a long absence from my hobbies, the changes over the years are quite saddening

[Radio Wrangler]

The shortwave broadcast bands are also steadily emptying.

There is extremely strong demand for frequency space up at UHF which suits portable devices with small antennae and relatively high data rates.

DRM doesn't seem to be taking over from AM in the LF/MF/HF world.

If you were a small broadcaster and wanted wide coverage, you'll already have set up an internet radio station. If you wanted coverage of roving listeners, then getting space on a DAB multiplex would look to you as a high-rent district, like hiring shop space in a trendy shopping mall must feel - only mass-market high-margin shops can afford those places.

If the big boys are all moved out of band II FM, then does that band go away, assigned to some other use? Or does it become a place where local coverage is somewhat cheaper than the multiplex space for small enterprises, special interest groups etc?

There is a lot going on (or off) in broadcasting these days. I think there is a future for VHF and higher frequencies, but the LF-HF bands are in free-fall.

I wonder if we will wind up with some AM transmitters in the hands of preservation societies, much like preserved steam railways? If so, considering the electricity bills these places run up and the maintenance costs of keeping tall masts safe, we might see only intermittent operation as funds allow. Advertisers might do some sponsorship, but their big budgets will be aimed at larger audiences. Grimeton in Sweden was a VLF morse station and is now a museum, it goes on the air occasionally and shows that something can be done. Enthusiasts raised funds to get their Vulcan flying but that proved too expensive to keep going. A radio station is at least an order of magnitude or so cheaper as a venture. Quartz Hill in New Zealand was a receiving station for signals to be re-transmitted. It wound up in the hands of a bunch of amateurs who had great fun until commercial pressure cleared the wire antennae and filled the hill with wind turbines. That's another pressure on the sort of sites radio transmitters occupy. High and windy land has become valuable.

With less pressure on frequency space, amateur bands have been expanded and some new ones created, which is fairly definite evidence that regulators and governments no longer see these areas as lucrative or important to national interests. Sadly, the amateur population is also reducing with younger entrants to the hobby not equalling the loss of older operators.

Saddening is a accurate description.

We've come to the end of an era of thriving activity. There's plenty of activity, but it's all moved off elsewhere. Mind you, even there things aren't as much fun as it used to be, what's the use of a TV with hundreds of channels and none worth watching for much of the time? I think that means the future is going to be via PVRs and VOD so that what's worth watching becomes available when you have time to watch.

David

[M0ALK Richard]

When you listen to local radio on AM they will tell you that they are available on FM, DAB and online (but no mention of AM).

Similarly we are told that we can listen to the cricket on Five Live Sports extra (but no mention of LW).

I also notice that my freeview channels now include BBC Radio Cambridgeshire and BBC Radio Norfolk.

[paulsherwin]

Actually, R4 idents have started mentioning LW again together with all the other outlets, though I doubt if this is very significant.

Big AM transmitters are closing for economic reasons, but Ofcom (and presumably other regulators) are refusing to licence new AM stations to fill the resultant gaps presumably for political reasons.

FM broadcasting is OT in this thread, but to clarify, there is no intention of ending FM broadcasting completely other than in the very long term. The current idea is to use FM for local and community stations with regional and national services moving to DAB. We shall see.

[Hybrid tellies]

There are some winners, well for a time, of these closures. Reception of some local stations and local MW relays will greatly improve after dusk. Some of the stations to benefit are Smooth in East Kent and BBC R4 in the Newcastle area on 603Khz, BBC R Cumbria and BBC R4 in west Cornwall on 756Khz, and Smooth in Southampton and BBC R Lancashire on 1557Khz.

[boxdoctor]

Hi D Cassidy,
Ydun Ritz's website has been running some years.
Quite a reliable gold-mine of information at times...http://mediumwave.info/news.html Tony

[stevehertz]

Originally Posted by D Cassidy

Hello Simon.
..... Certainly Medium Wave is so much quieter than it was twenty years ago. .....

I wish it was...

[Hartley118]

It's not that the MW is getting quieter, just that useful stations are gradually being replaced by transmissions from wall warts and other switched-mode stuff!

Martin

[G6Tanuki]

That's a real issue, particularly in urban areas. If you're living in a tower-block and you tune across the MW band you're more likely to hear the wall-to-wall QRM from the neighbours' 50-inch plasma-TV or the braarp-braarp 'powerline internet' plugs in the flats-across-the-way, than any worthwhile entertainment.

Since around 2000, when OFCOM have been inviting 'bids' for licences, it's been growingly rare for anyone to respond if the licence is for a MW/LW AM slot. Providers just don't see these frequencies as being worth bidding/paying for.

The world's moved on. Truth is, a MW/LW Am allocation only gives you 4.5KHz of frequency-response. OK perhaps for talk-radio but gruesome for music.

Even the pirates have stopped broadcasting on medium-wave. That must mean something!

[Hybrid tellies]

Actually the AM audio frequency response gently tails off just above 6Khz and is the reason why it can sound good. I listen to BBC R5L, BBC R Bristol and Absolute on AM on my more vintage radios and a few people have been amazed at the sound quality thinking that the they were listening to an FM transmission. I know many of Forum members will agree. With the German and French AM closedowns there will be some of us in this country which will be able to enjoy good AM reception from their local stations 24/7 for the first time.

[G6Tanuki]

Originally Posted by Hybrid tellies

Actually the AM audio frequency response gently tails off just above 6Khz and is the reason why it can sound good.

The European channel-spacing on MW is 9KHz; meaning that to stay within their allocation an AM transmitter needs to impose some serious HF-cut on any components above 4.5KHz if their sidebands are not going to intrude on their upper/lower-frequency neighbours' allocations.

OK, if there's no active transmission on either of their immediate upper or lower neighbour-channels (which in these days of abandonment of AM/MW allocations is quite likely) they may get away with letting their transmissions be 'a bit wide' if the authorities aren't that diligent.

Whatever, any AM MW/LW transmission is never going to deliver the up-to-15KHz bandwidth that we expect these days for anything other than "voice quality" audio.

[Synchrodyne]

Originally Posted by G6Tanuki

The world's moved on. Truth is, a MW/LW Am allocation only gives you 4.5KHz of frequency-response. OK perhaps for talk-radio but gruesome for music.

And probably made worse courtesy of Optimod...

But, with fewer transmitters in the band, perhaps it is time to step away from the practice of using severe low-pass filters in the audio path for MF transmitters in the UK, and allow at least say the US NRSC bandwidth of 10 kHz.

By the way, when did the MF audio bandwidth limit in the UK become 4.5 kHz? The BBC started using a 5 kHz filter (its FL4/55) circa 1973. By the early 1990s, the upper limit had become a nominal 6 kHz (±3 dB up to 5.8 kHz), with 24 dB/8ve roll-off after 6 kHz. And 1977 data shows that the IBA was using a filter with steep roll-off after 5 kHz.

Before the early 1970s, the program distribution landlines were the main determinants transmitted MF bandwidths. The BBC appears to have had an 8 kHz landline target (not always reached) through the 1950s, moving up to 10 kHz in the early 1960s. However, the lines to the Brookmans Park transmitter were flat to 15 kHz as early as the late 1940s.

Cheers,

[Synchrodyne]

I wrote my previous post before seeing Hybrid Tellies’ post.

So it looks as if the 6 kHz limit still applies in the UK. That AM transmitted bandwidth is, or should be limited to half the channel separation is a myth that has been perpetuated very widely since the 1950s at least. One wonders if it was started by the receiver makers to excuse their use of narrow bandwidth IF sections that limited the AF response to 5 kHz or less.

15 kHz audio bandwidth is possible with AM and has been done, as evidenced by the BBC Brookmans Park case. In the USA, some broadcasters who were using this bandwidth were rather upset when the NRSC rules came along in the 1990s and limited the bandwidth to 10 kHz. I have a Carver TX-11a tuner, from the mid-1980s, and oriented towards US conditions of its time, that offers an AM bandwidth of 15 kHz (at -1 dB) in “wide IF” mode. That was probably a bit more many wide band AM receivers, which typically went to 10 kHz or a bit beyond.

The 6 kHz bandwidth, whether by design or incidentally, aligns with HF broadcast practice, where this was the de facto upper limit. Whether by cause or effect, this aligns with the bandwidth provided by HF SSB and ISB program links, going back to the 1930s.

Cheers,

[G6Tanuki]

Originally Posted by Synchrodyne

The 6 kHz bandwidth, whether by design or incidentally, aligns with HF broadcast practice, where this was the de facto upper limit. Whether by cause or effect, this aligns with the bandwidth provided by HF SSB and ISB program links, going back to the 1930s.,

I guess it made sense up until the 1980s: until then, in Europe the MW band - specially after dark - was full of competing Megawatt-plus stations and for maximum propaganda-effect they wanted to focus the majority of transmitted energy into their allocated channel and not waste anything by spilling-over into adjacent channels.

[This was not always the case; some of us remember at the HF end of the medium-wave band hearing Bulgarian "Stara Zagora" and the dismal Radio Tirana fanfare splattering 20KHz either side of their allocated slot, despite having decently-selective receivers like a dual-diversity AR88D and Eddystone 730/4 as our program-source].

Radio Tirana station-ID: https://youtu.be/B2mBP40w_hU