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View Full Version : BBC to trial DRM on medium wave from Plymouth


MikeB
09-02-2007, 15:47
http://www.bbc.co.uk/pressoffice/pressreleases/stories/2007/02_february/09/trial.shtml

FritzWue
11-02-2007, 09:56
The trial will be broadcast on 855 kHz.

For me there is hardly any chance to receive anything as there is a local 5kW AM station on 855kHz just 40km from here. :(

jbriggs
12-03-2007, 14:58
Here is a link to the FAQ's, I guess this was needed after it was announced the MF frequency would "end" in the Plymouth area.

BBC test faq (http://www.bbc.co.uk/devon/digitalmediumwave/faqs_feature.shtml)

jbriggs
02-04-2007, 14:00
and here's a link to the legal jargon for those participating in the test:
jargon (http://www.bbc.co.uk/englandcms/digitalmediumwave/terms.shtml)

MikeB
02-04-2007, 15:54
Are they using the Morphy Richards for the trial or the Himalaya models that were used in Kigali?

A contact of mine has just rung BBC Radio Devon, the analogue signal was switched off yesterday and they are anticipating that the DRM tests will commence on April 23rd.

jbriggs
02-04-2007, 16:04
Hi Mike,
I don't think it has been decided yet but my contact said ideally a mixture of different receivers would be best for the trial. So in reality that's likely to be a mixture of the Morphy and Himalya as they are the only 2 Rx to have been made in significant quantities to date.
James

DRM-Fan
02-04-2007, 22:07
Is it live live then ? I guess not, what's the delay ?

simone
03-04-2007, 15:17
....a mixture of different receivers would be best for the trial.
James
It would be great if there would also be a Rx for mobile reception available for the trial.
Simone

MikeB
03-04-2007, 21:27
Interesting piece here about how the BBC engineers are measuring local
interference whilst 855 is off the air:

http://www.bbc.co.uk/devon/digitalmediumwave/its_all_gone_quiet_feature.shtml

FDJ
12-04-2007, 07:27
Interesting piece here about how the BBC engineers are measuring local
interference whilst 855 is off the air:

http://www.bbc.co.uk/devon/digitalmediumwave/its_all_gone_quiet_feature.shtml





Radio Devon are now radiating a "test loop" presumably until the service officially goes live.


Frank

jimbo
12-04-2007, 22:19
Hi. Can I ask - is anyone able to record the audio so I can hear it? Thanks.

FDJ
13-04-2007, 16:38
Hi. Can I ask - is anyone able to record the audio so I can hear it? Thanks.
Sorry, I have had to remove the file.

Frank

jimbo
13-04-2007, 23:22
Thanks for that. I wonder how far it gets out at night?

simone
14-04-2007, 18:43
Thanks for that. I wonder how far it gets out at night?

And even more interesting would be to see a logfile showing how bad results get at night at maybe 15- 20km from the Tx where it works OK at daytime.
Simone

jbriggs
16-04-2007, 14:57
Frank - thanks for the Mp3 file, it does not sound too bad at all, what bitrate was being used (for DRM not Mp3)?

Concerning the logging, I recently saw a presentation at BBC R&D, they mentioned there will be 2 or 3 long term logging receivers in the Plymouth area that are already set up. I think some of these Rx will be in the 15 - 20 km range, and so will pick up & log skywave interference. In fact they even demonstrated an application to send the received audio via the internet (both AM and DRM) combined with Google Earth - it was a very impressive demonstration.

James

FDJ
16-04-2007, 19:16
Frank - thanks for the Mp3 file, it does not sound too bad at all, what bitrate was being used (for DRM not Mp3)?
23k.

Concerning the logging, I recently saw a presentation at BBC R&D, they mentioned there will be 2 or 3 long term logging receivers in the Plymouth area that are already set up. I think some of these Rx will be in the 15 - 20 km range, and so will pick up & log skywave interference. In fact they even demonstrated an application to send the received audio via the internet (both AM and DRM) combined with Google Earth - it was a very impressive demonstration.

James


Signal is not so good here. Too much man-made noise:mad:

Frank

richard
17-04-2007, 10:12
Hi Frank, can I ask out of interest what antenna do you use with the WinRadio?

Richard

DRM-Fan
27-04-2007, 21:58
Could we have a new sample from Radio Devon as they are now using stereo mode sounfing very good apparently acc to one listener who was given a roberts radio for the trial

jbriggs
30-04-2007, 21:54
Could we have a new sample from Radio Devon as they are now using stereo mode sounfing very good apparently

I am planning a trip down to Plymouth tomorrow, I am going to take a Fraunhofer DT700 receiver, & will make a few recordings. Hopefuly I will post some MP3's and thoughts on coverage tomorrow.

James

DRM-Fan
02-05-2007, 20:50
I am planning a trip down to Plymouth tomorrow, I am going to take a Fraunhofer DT700 receiver, & will make a few recordings. Hopefuly I will post some MP3's and thoughts on coverage tomorrow.

James

How did you get on James ?

jbriggs
03-05-2007, 23:35
Hi, Sorry for the delay, we had a good day checking reception of the Plymouth transmitter. I would say reliable coverage extends for 20 miles (30km) around the transmitter and it is possible to get audio up to 35 miles away but only when conditions are right. We managed to get the service ID at Honiton (95km) SNR about 5dB with a large unidentified co-channel interferer. These were daytime measurements would be interesting to see what happens at night I suspect the service area shrinks a bit.
There was a discussion about the trial on air while we were recording, I hope to get that audio extracted and posted next week as an mp3 file. I also already asked Simone to host a 28 second wav file to give an idea of sound quality. Be warned the file size is large as its uncompressed! Simone can you post a link to that file below?
Thanks James

RadioDevon_SandyDenny.wav (www.stoepplernet.de/drm/RadioDevon/RadioDevon_SandyDenny.wav) (4.8 MB), the service was running 23kbps in Parametric stereo with a 15.375kHz audio bandwidth

DRM-Fan
04-05-2007, 01:27
Hmm great. DRM is very well suited for MW, hope we have some more tests in the future from other MW relays. If you had recorded on a MR radio then the DRM file could have been played on any other MR radio of course, oh well !

jbriggs
09-05-2007, 16:07
Here are some maps created from the data we recorded. The required SNR for audio was about 13 dB or better.
Thanks to Simone for creating and hosting the maps!
James
you really need a broadband connection to view these links

route from Exeter towards Plymouth transmitter (http://www.stoepplernet.de/drm/radevon_all.html)

results from within the service area of the transmitter (http://www.stoepplernet.de/drm/radevon_end.html)

:D

BofH
20-05-2007, 23:47
Any chance of testing at the maximum bitrate (PL 3 @ approx 30.8 kbps)

It would be good to compare the increased audio quality with any potential loss of coverage.

jbriggs
23-05-2007, 09:50
Hi BofH,

I don't think NGW/BBC (the trial sponsors) will be inclined to change any of the parameters now for the rest of the year long trial, as it will just lead to confusion amongst the 100 or so panel of listeners.
I think the Mode/bitrate they chose was a good choice. The higher bitrate would make the signal more prone to dropouts, and while 30 kb/s sounds fantastic with the DRM AAC audio codec, dropouts are more annoying than the slight improvement in sound quality going from 23 to 30 kb/s.

James

MikeB
24-05-2007, 11:25
I don't think NGW/BBC (the trial sponsors) will be inclined to change any of the parameters now for the rest of the year long trial, as it will just lead to confusion amongst the 100 or so panel of listeners.

Is it just one transmitter, IIRC I read somewhere that they were hoping to set up a single frequency network. Looking at the last Ofcom future of radio document they seemed interested in using DRM in this way.

jbriggs
29-05-2007, 13:49
It is just one transmitter at the moment although I think there will be a 2nd one added later this year at another location but using the same frequency.

James

digitalradiotec
06-06-2007, 19:11
Could anybody tell me what the bandwidth is on the BBC Radio Devon trial signal please? And is the bit rate 23 kbps or is it 23.6 kbps? Thanks.

edit: new thread merged with the already existing thread, Simone

simone
06-06-2007, 20:47
Bandwidth should be 9 kHz, if you mean only the audio bitrate, it is 23 kbps, parametric stereo as I already mentioned here:
http://www.drmrx.org/forum/showpost.php?p=37936&postcount=21
Simone

simone
07-06-2007, 09:15
Hi digitalradiotec,
after having a look at your website I wonder about your question here, the missing 0.6 kbps would probably not help you!
quote from your website:...they're using a bit rate as ridiculously low as 23 kbps, it is inevitable that the audio quality would be very poor
Although I can not listen live on this transmission, I agree with James (see post from May 23rd) that the mode/ bitrate are a good choice, two of our ARD stations are using the same configuration for audio (not the dataservice) and sound quite good.
Simone

digitalradiotec
07-06-2007, 13:57
Bandwidth should be 9 kHz, if you mean only the audio bitrate, it is 23 kbps, parametric stereo as I already mentioned here:
http://www.drmrx.org/forum/showpost.php?p=37936&postcount=21
Simone

Thanks very much.

digitalradiotec
07-06-2007, 14:09
Hi digitalradiotec,
after having a look at your website I wonder about your question here, the missing 0.6 kbps would probably not help you!
quote from your website:...they're using a bit rate as ridiculously low as 23 kbps, it is inevitable that the audio quality would be very poor
Although I can not listen live on this transmission, I agree with James (see post from May 23rd) that the mode/ bitrate are a good choice, two of our ARD stations are using the same configuration for audio (not the dataservice) and sound quite good.
Simone

We'll have to agree to disagree then, because I've reviewed the Morphy Richards 27024 for a hi-fi magazine, and I've listened to quite a few other recordings of similarly low bit rate DRM transmissions, and I think the audio quality is terrible - although it's hardly surprising that it is terrible considering how low the bit rate is...

If you read my website you will see that I am very critical of the audio quality on DAB, but I would say that the audio quality of low bit rate DRM stations is significantly worse than on DAB.

The way I look at this situation is that comparisons with AM radio are irrelevant, because this is the 21st century, and IMO, a digital radio system should either provide good audio quality or it shouldn't be used at all (in the developed world, at least).

An obvious solution would be to use 20 kHz channels instead of 9 or 10 kHz, but these 23 kbps streams are a joke, I'm afraid.

Sorry to be blunt, but that's how I feel.

jbriggs
08-06-2007, 13:51
Hi digitalradiotec, I read your post with interest and I do have some sympathy for your position.
However my personal experience of listening to the different bitrates of DRM (and I have quite a nice presentation with different audio samples with bitrates going from 4 kbps to 40 kbps, unfortunately far too big in size to e mail) is that there is a dramatic increase in audio quality from going from 4 kbps to 20 kbps but adding extra bits rate after 20 kbps gives diminishing returns in terms of improved audio quality. BTW if you think 23 kbps is "a joke" I wonder what term you can use to describe audio at 4 kbps!?

I have come across certain people in the industry who have a remarkably tuned ear and can hear imperfections that 99 % of people would not notice. I suspect you are in the 1% category. To me in a normal listening environment (home) I don't perceive much difference in the sound quality of a 23kbps AAC DRM bitrate and one of 35 kbps. Once in a car then with the background noise I think the benefit of using higher bitrates is even less. Call me Mr Average but at the end of the day the majority of people will be happy with 23kbps.

It will be interesting to see the results of the trial when they are published in a year or so as there will be a survey of perceived audio quality. I bet the majority of people will be satisfied (or better) with the audio quality.

Having said all of the above, there was a recent test in India using 18 kHz wide RF signal with a bitrate of about 35 kbps which went down very well with the ABU.

James

jbriggs
08-06-2007, 14:11
Talking of sound samples here is an MP3 file (off air recording while I was driving around on 1st May) that has the Radio Devon DJ talking about the Radio Devon DRM trial
radio devon comments on digital trial (http://www.stoepplernet.de/drm/RadioDevon/BBC_RadioDevonTrial.mp3)

jbriggs
14-06-2007, 12:31
Here are some more samples of Music that I recorded off air on May 1st that we (Simone & myself) finally got round to extracting from the recorded data file.

here comes the sun (good stereo effects) 1.25MB (http://www.stoepplernet.de/drm/RadioDevon/devon2a.mp3)

every possible way 3.3 MB (http://www.stoepplernet.de/drm/RadioDevon/devon2c.mp3)

Is this quality of audio acceptable or not? Would you listen to this instead of an FM station?

James

DRM-Fan
17-06-2007, 20:21
Here are some more samples of Music that I recorded off air on May 1st that we (Simone & myself) finally got round to extracting from the recorded data file.

here comes the sun (good stereo effects) 1.25MB (http://www.stoepplernet.de/drm/RadioDevon/devon2a.mp3)

every possible way 3.3 MB (http://www.stoepplernet.de/drm/RadioDevon/devon2c.mp3)

Is this quality of audio acceptable or not? Would you listen to this instead of an FM station?

James

It's very good with me. Not perfect but considering what awful MW quality we've had to endure for decades in the UK DRM is like CD quality in comparison, not that it is of course. Come BBC and ILR get your act together we need dozens more stations switching to DRM asap

simone
17-06-2007, 21:04
The recordings have been linked from a Chinese radio forum (http://bbs.leowood.net/web/leowood/forum/forum_read.asp?id=2976991&page=1&property=0&ClassID=0),would be interested to know what they think but unfortunately I am not able to understand any of the comments there :(
Simone

zfyoung
18-06-2007, 01:20
Hi,every one. I'am the person who put the link to that Chines radio forum. I just want to raise the public awareness of this new digital mode, and see the reaction.

Generally, they are very satified with its high audio quality.Some of them comment it's even more stable than FM. At the same time, I can see ordinary radio listeners are eager to take up this new technology, unfortunately "Plymouth" is a long way off China and China lies in the shadow of DRM "black hole".

simone
18-06-2007, 03:50
Hi zfyoung,
thanks for your reply, looking at the number of downloads refering to the Chinese forum there must be quite an interest in DRM among those listeners.
Simone

johnn
18-06-2007, 14:16
James,
Many thanks for the audio samples from Radio Devon. As a DRM listener from early 2004, I can only receive longer distance stuff at my location, mainly SW + 1440,1593 & 177kHz. I have listened to Orfordness using the DX Tuner system from Sweden & 855kHz seems nearest to that in quality. The DX Tuner thing is now closed, so that's out!
I would be interested to know why Radio Devon's MW was picked for the trial, other than maybe a low audience.
JOHN.

MikeB
21-06-2007, 13:46
Here are some more samples of Music that I recorded off air on May 1st that we (Simone & myself) finally got round to extracting from the recorded data file.

here comes the sun (good stereo effects) 1.25MB (http://www.stoepplernet.de/drm/RadioDevon/devon2a.mp3)

every possible way 3.3 MB (http://www.stoepplernet.de/drm/RadioDevon/devon2c.mp3)

Is this quality of audio acceptable or not? Would you listen to this instead of an FM station?

James

Used standard computer speakers and medium range hi fi speakers, no line in to my portable radios unfortunately.

Interesting examples, first one I found too flat, compressed and with some artefacts, when the percussion comes in it becomes irritating as the higher frequencies aren't there. It's a track I have heard a lot.

Second one, which is a more modern track and with, I think, less instrumental variation on the track, sounds poor at the start (a bit odd, sounds as if the sound level has been set too high briefly) and then is broadly acceptable, apart again from the percussion at times. The SBR, to me, just doesn't seem to work as well as it seems to claim on the Coding Technologies website. Does switching off the parametric stereo improve the audio?

Going back to the speech sample you posted earlier that sounded fine.

Not sure in what context you are asking the last question, i.e. switching off FM or a music station competing with FM, so I'll answer it in my own way.

Broadcasting is becoming multiplatform, including digital, and DRM itself can be used on different bands and with different parameters, particularly when the DRM+ standard gets ratified. The examples illustrated, particularly the first one, are not, to me, an acceptable alternative to an FM music station, given good FM reception with no multipath distortion. But an FM station could migrate to DRM+ anyway and get the same coverage area, they could even start on Band 1 and migrate up to Band 2 at some point if it is decided to work towards analogue switch off.

The second track would be acceptable for listening in the car or at home as background listening, however I would expect that there would be an internet or satellite feed of better quality, given recent advances in internet audio, for more serious listening. The first track needs a higher bitrate. Going back to your previous point, about 23.6 kpbs being used in the tests and not being varied, according to the drm.co.uk website you can use 27.8 or 30.8 kbps with less protection. If AM is going to be used as a single frequency network can't you then use an increased bit rate as the extra transmitter(s) will help in maintaining coverage in fringe areas.

As I understand it the BBC is testing DRM on AM mainly as one possible digital alternative in areas where DAB can't penetrate. I see from a recent report in Media Guardian that they are looking at DRM as well as satellite and wifi in this context.

Why put music stations on medium wave DRM at this bit rate given the alternatives? I would look to be putting mainly speech networks on DRM AM at European 9 khz bandwidths which in itself would free up other digital modes, i.e. DAB, DAB+, DRM+ for music stations. I appreciate Luxembourg sees it as a fill in service for areas of France and Germany where they can't get FM coverage and that DRM is useful for international broadcasters but do national broadcasters need it for music based services?

Of course you need the receivers on the market and we have an increasing number of DAB MP2 receivers in the UK which is a legacy problem for possible DAB+ migration never mind possible future DRM usage.

simone
21-06-2007, 16:23
Seemed to me that they are doing lots of phone conversations on the program, so they would certainly not need the par. stereo and could easily even reduce the bitrate.
In a car or on portable radios the audio quality for me is OK to listen also to music occasionally, but in general I think DRM should be used to replace AM transmissions with mostly speech. Especially on DRM transmissions of international broadcasters it is not the chosen bitrate that is limiting the audio quality, quite often it is the quality from the studio or the audio feed (quality and audio bandwidth).
Simone

MikeB
25-06-2007, 15:51
The BBC has given its views on DRM in sections 17 and 18 of its response to the Future of Radio consultation, sections 14, 15 and 16 state that the BBC remains a major user of medium wave, Five Live having a weekly reach of 6 million and it being an important and integral part of local and regional coverage :

17. Given our usage of medium wave, and the potential short-comings of local radio on DAB, we have begun a trial of the only alternative digital radio technology which seems suitable for this waveband: digital radio mondiale (DRM). The trial is re-using the frequency for BBC Radio Devon in Plymouth, converting this to DRM operation, and then researching the reaction to it with a specially selected audience panel. The transmission has been in operation since the end of April 2007 and it is too early to draw any conclusions from the trial. Nevertheless, it demonstrates that DRM on medium wave in the UK from an existing transmitting station is technically possible, even if there are
considerable engineering challenges to be met.

18. For this reason, we consider that it is too early to determine whether DRM has a part to play in the future of radio. Just as it was with the introduction of DAB, the key will be the availability of radios which are able to receive the transmissions. We believe that the next three years will be crucial for DRM, as the intentions of radio manufacturers become better known and the technologies of choice for the future become clearer. In three years, there may well be DRM networks on-air or planned in other countries and the use of DRM for international broadcasting may have brought the receiver market to maturity.
Similarly, over the next three years, DAB+ may have been sufficiently adopted to have become built in as default to receivers (and we note that if it did, its elements of commonality with DRM may make it easier to implement the latter in receivers also). In the same timescale, WiFi radio may be better established and Wimax might have come to fruition. To make a decision now on the choice of technology is too soon.

The full BBC response may be downloaded at:
http://www.ofcom.org.uk/consult/condocs/futureradio/responses/

Sections 12 to 34 give the BBC's views on use of digital technologies.

jbriggs
27-06-2007, 21:38
Hi Mike thanks for the posts.
Does switching off the parametric stereo improve the audio?
The Parametric stereo does have a small bitrate overhead so I personally would not use it below 22 kbps as I think its better to put all the available bits into the basic mono AAC encoder. Having said that I do see some broadcasts using Parametric stereo with datarates as low as 17 kbps.

BTW here's some information I found on a press release from UBC that mentions the Radio Devon transmissions: Its quite long so I edited it and just left in the stuff about Plymouth. Full press release is on the UBC web site. I think this explains the "missing" 0.6 kbps referred to in an earlier post on this thread!

25 June 2007
.... and BBC use UBC software for Digital Radio Mondiale initiative in the UK

UBC Media Group plc (UBC:L) today announces .... In addition, it announces that the BBC has chosen Unique Interactive to provide Display Text and Electronic Programme Guide (“EPG”) data for their Digital Radio Mondiale (“DRM”) trial in the UK.

...

The EPG Management system collates programme schedule information such as the name of the show, the presenter and additional programme details and sends it for broadcast, for display on DAB, DTTV, DRM, HD Radio and Satellite Radio receivers.

....

The BBC’s DRM initiative is centred in the South West of England, and is set to assess the practicality of digital radio services in the medium wave bands. DRM is an emerging technology that has been designed to facilitate digital radio at frequencies below 30 MHz. The trial commenced in April 2007 and will report in mid 2008. Unique Interactive will be supplying their “ManDLS” Display Text and EPG Management software for the trial.

Simon Cole, Chief executive of UBC commented:

“We are thrilled to see such validation of our investment in software products from major global radio companies. ....... The BBC trial also fits with our belief that digital radio is ubiquitous and platform agnostic and we very much look forward to working with the BBC towards its successful completion of the trial”
...

John Allen, Head of New Services, BBC English Regions, added

“The addition of the EPG on DRM receivers lets users discover our radio programmes as easily as possible adding an extra dimension to the trial that we hope will prove compelling to our listeners. Unique Interactive is leading the field in this area and is already providing EPG services to the UK DAB market."

simone
28-06-2007, 11:49
John Allen, Head of New Services, BBC English Regions, added

“The addition of the EPG on DRM receivers lets users discover our radio programmes as easily as possible adding an extra dimension to the trial that we hope will prove compelling to our listeners. Unique Interactive is leading the field in this area and is already providing EPG services to the UK DAB market."

I wonder about that, I thought the listeners on the trial are using the Morphy Richards or Roberts MP40, as far as I know both do not support the EPG.
Simone

mitajohn
28-06-2007, 16:49
Hi all,

I found the attached, rather interesting article in Pro Sound News June 07 issue, about DRM in Devon and I got a scan (not so good) for you.

MikeB
13-07-2007, 15:09
BBC adds text and EPG data to its DRM trial

http://blogs.rnw.nl/medianetwork/?p=8420

MikeB
25-07-2007, 17:31
Photos of Plymouth MF transmitter site, the final photo is of BBC Radio Devon's DRM transmitter and it confirms that they are now running a single frequency network with the second transmitter at North Hessary Tor:

http://www.flickr.com/photos/davidcjones/sets/72157600921443602/

Mike

MikeB
23-05-2008, 11:54
The trial has finished - the 855 transmissions are still on the air although they will be withdrawn "sometime in the future", long email from the BBC about the trial at the link below:

http://www.digitalspy.co.uk/forums/showpost.php?p=23916403&postcount=14

simone
24-06-2008, 19:55
Good results recently, very stable reception in Tavistock and only a few dropouts when driving on Dartmoor, the big dips in the first log were a Rx problem.
No dsl during those days and no useful information in the EPG files.
Simone

FDJ
31-10-2008, 10:24
DRM TX was switched off today.