The Lion, the Witch and the Wardrobe.

watty

* A little bird tells me that RTE are enthused about DAB so more will happen soon

* DRM instead of 252AM looking more likely with MW AM to follow.

* Contracts etc done and Multiplex suppiler installing gear on sites shortly for 2 year DTT trial.

DAB is only at low power, perhaps to give UPC/NTL time to fix the cable system. This also is suggested reason why Europe's most cabled City is getting DTT before us outside here.

Woodcock Hill Limerick (OK it is in Co. Clare) is upgrading in next two weeks from Transposers (rebroadcast from Maghera) to Transmitters (dunno how fed, but a video feed, not RF). Same power.

Obviously RTE isn't run by the same people as a well known phone company

Foggy43

I am interested in what you are saying.

Just to clear something up. RTE will not use DAB but DRM (a choice imposed on them by Comreg.) RTE did use DAB but as a trial only.

Getting hold of a DRM recevier isn't easy at the moment. I did read a story that a DRM trial was going on in London. I'm sure if there was DRM radios would be available on Tottenham Court Road.

L1011

Erm, my own sources suggest that RTÉ will continue to use DAB for the national networks. Comreg's recommendation (not forced) was to use DVB-T radio, not DRM. DRM will be used on longwave and/or mediumwave but DAB to complement/eventually replace FM. Not DRM.

I've got a DRM radio here, but as its DRM and not DRM+, it doesn't do VHF delivery, etc. As these don't exist yet, at all...

watty

No, Molly, RTE may use DAB (VHF) and may also use DRM (LW, MW).

DRM+ is only really a proposal.

At the minute DRM is musch limited to Communications Receivers. TenTec have it.

If you add a conversion module from existing Radio IF to 12.5KHz IF, a PC with sound card can demodulate the DRM using either Official DRM software (you buy it) or unoffical DReaM software (free).

DRM can easily replace AM as it is so much better than AM on LW, MW and SW and also AM listnership is very low (Turning off 2FM on MW a pre DRM experiment?)

DAB is more likely to complement FM VHF for a long time in Ireland.

DRM, DAB and DVB-t and DVb-h use the BEST method for terrestrial broadcasting invented COFDM
COFDM systems in widespread use:
http://en.wikipedia.org/wiki/DVB-H
http://en.wikipedia.org/wiki/Digital_audio_broadcasting
http://en.wikipedia.org/wiki/Digital_Radio_Mondiale

Narrowband
http://n1su.com/windrm/new/WinDRM_Docs.htm
http://drm.sourceforge.net/ DRM has a 2.5Khz bandwidth mode not mentioned in Wikipedia above. This SW receives comercial DRM, AND works as two way radio at 2.5KHz DRM.
http://en.wikipedia.org/wiki/Q15X25 Very narrow band, but only data, not speech capable

Mostly the issues with DAB is NOT the broadcast modulation but use of MP2 speech compression (better codecs now available) and too many sations on UK multiplex makes bitrate too low.

If Bit Rate is 192k or 256k DAB is fine.

A system with the DAB transmission but DRM codec (AAC?) would be good for VHF. But it is in a way too late. This is a little like what the DRM+ proposal is.

Satellite DVB-s uses a DAB style codec (MP2) but mostly at 256K for Radio Stations. Which is why in UK the same station sounds worse on DAB as it is implemented (128k for same station).

Some are experimenting with DAB rather than DVB-h for phone video content, but DVB-h is much more popular allready and is likely in USA and Europe generally. Germany may have only large trial of DAB for video on phones.

Foggy43

Watty!
I don't know why I mentioned DRM. It was DVB-T that Comreg preferred to DAB as MYOB pointed out.

I remember on previous threads people would rather not have DAB as it used MPEG2 as opposed to the DVB system that use MPEG4 which will give far better sound quality. In my case DAB is far better quality which is down to my location. Band 111 coming in far beter than Band 11.

DVB-H is on trial almost a year now in Oxford. I think they are finding that people are using it at far more often at home rather then when mobile. I can't say I am particularly interested in it. Of course the cost will be a major factor. I am not sure if the UK goverment have or will close the 'TV License' loophole that existed with DVB-H when it started.

Now it is back to the links on your last post. Lets see how much of this I can take in :eek:

L1011

DVB-T "radio" currently only supports Musicam MPEG1 audio, the same as DAB uses. MPEG-4 DVB-T will, when standardised and in use, support the same AAC/HE-AAC than DABv2 will; but neither is available yet.

watty

DAB isn't MPEG2 it is MP2 Audio. MPEG2 and MPEG4 are Picture Codecs and MP2, MP3 and AAC are sound codecs.

MPEG1 is the mkII codec for VCD, There is an earlier slightly different MPEG1 for original CDi. MPEG1 is only a video codec.

DVB-s, DVB-t and DVB-c only differ in modulation. The Data stream is MPEG2 for Video and MP2 for mono/stereo and AC3 for surround / multichannel sound. In theory MP1 could be used but I don't think it is. The same can be used on DVD, but some DVB resolutions of video are not supported on DVD. DVD supports commonly a few other audio codecs.

Not MP3 nor AAC are part of standard DAB, DVB-s, DVB-t, DVB-c or DVD specs that use MPEG2 video.

DVB that uses MPEG4 is a new standard, different from original DVB. The MPEG4 version of DVB is now standardised and chips available. The MPEG4 is primarily for HD, but has some advatages for ordinary video especially on lower bit rate channels with AAC audio codec.

You can just use DAB or DVB as a wrapper and stick any kind of data or any codec (e.g. MP3 audio) but without any G'tee that anyones receiver other than a PC card with downloaded SW will work.

bk

watty wrote:

DAB isn't MPEG2 it is MP2 Audio. MPEG2 and MPEG4 are Picture Codecs and MP2, MP3 and AAC are sound codecs.

Just a small correction, MPEG2 and MPEG4 are not video codecs, they are standards for audio and video and they included the standards for audio and video.

For instance MPEG2 includes 10 parts, including:

Part 2 is the video codec.
Part 3 is the audio codec, MPEG 2 Part 3, otherwise known as MP3 *
Part 7 is another audio codec, Advanced Audio Coding (AAC)

the other parts of the spec are for transmission support, etc.

* MP3 was actually part 3 of the MPEG 1 spec, MPEG2 Part 3 is an extension for multichannel audio.

http://en.wikipedia.org/wiki/Mpeg2

MPEG-4 has 22 parts, inluding two video codecs and a couple of audio codecs and lots of other stuff:

http://en.wikipedia.org/wiki/MPEG-4

watty

OK BK you get the pedantic medal off me today! Though you are slightly in error

I think you know what I was trying to say though

I don't think MP3 = MPEG2 Part 3 though.
Part 3 is the Audio codecs spec.
MP2 (audio files) refer to MPEG-1 Audio layer 2 or MPEG-2 Audio Layer 2
MP3 (audio files) refer to MPEG-1 Audio Layer 3 or MPEG-2 Audio layer 3

The Wikipedia articles are slightly confusing (as is the subject) and not 100% accurate.


MPEG = Motion Picture Expert Group

MPEG-2 should not be confused with MP2, or MPEG-1 Audio Layer 2

http://en.wikipedia.org/wiki/MPEG-2

L1011

bk wrote:

Part 7 is another audio codec, Advanced Audio Coding (AAC)

Which, like MP3 being extended in the MPEG-2 specbooks, is extended again in MPEG-4 Part 3, which is usually the spec thats in general usage.

bigbob

Watty, have heard which tranmitters will trial dtt?

watty

I think Three Rock and one or two other East coast TX sites.

Very, very soon.

lawhec

watty wrote:

I think Three Rock and one or two other East coast TX sites.

Very, very soon.

I'd love for Truskmore to be included (considering that much of its coverage area will have a ready-installed Freeview STB base), but I'd doubt it very much

Mayo Exile

I think Three Rock and one or two other East coast TX sites.

Clermont Carn in north Co. Louth is also scheduled for DTT testing i think. Also quite a number of people here will have Freeview boxes due to its proximity to the border. I presume these will work ok with Irish DTT tests?

mrdtv

They will do unless they encrypt the service which is highly unlikely. The UK boxes nowadays are DVB-T all modes (some even do hierarchical demodulation) and should have no problems. The old ITVDigital boxes probably won't work as they were mostly 2k only.