Bernie Newnham
Back in the mid nineteen-eighties BBC research invented a digital sound system – NICAM. It was used in a lot of places and may still be. I played a tiny part because I made the video for IBC that sold it. I may still have it somewhere.
I thought [those interested in Sound] would appreciate this –
https://www.mattmillman.com/remembering-nicam-part-1-broadcast-equipment-teardown/
| NICAM Digital Audio first went on air in 1986 and is one of the, if not the, first digital broadcast received by households in much of Europe and Asia/Oceania (excl. Australia). It is well remembered by both AV enthusiasts and audiophiles for providing near CD quality audio alongside analogue television broadcasts. For my teenage self, watching the music video charts with the stereo attached to a NICAM receiver was always a highlight of the week. |
Chris Woolf
Lest our rose-tinted specs colour our judgement too heavily, we should remember that France and Italy produced similar companded stereo line transmission systems at the same time, and that they were all to do with digital transmission of audio through the European telecom unified E1 network system.
The BBC research department held considerable power at that time (early 1960s) as an adjudicator in systems, and picked the NICAM2 system that it had been partly involved in developing, in preference to the other systems for transmission to its transmitters.
NICAM 728 – the TV stereo broadcast system – was much more the product of BBC Research, and borrowed on the successful compander approach of NICAM2.
In the early days BBC Research was indeed a splendid institution, but Auntie has never been above spinning many broadcast developments as its own, when that hasn’t always been the case – and that these techniques were the best thing since sliced bread, even when that wasn’t always true. It is wise to stand aside from the Brito-centric view at times, to avoid being sucked into it and becoming sadly blinkered.
The US is a nation that struggles with this sort of self-delusion – it invented absolutely everything, won every war, and can’t understand why its laws and ethics don’t apply to the entire world. Only those separated by a big ocean are able to judge more accurately.
Alan Taylor
NICAM was used to transmit stereo sound via analogue TV transmitters. I believe that all transmitters have now gone digital and presumably NICAM is no longer used.
I remember the days when the BBC transmitted experimental stereo programmes (sound only) using an FM receiver and a TV set. The idea was that those two devices were capable of reproducing relatively high-quality audio and many families had both in one room.
There were any number of technical reasons why it was a poor way of implementing stereo and I don’t recall the experiments continuing for long.
FM radio wasn’t available until 1955 and the television was the highest quality sound source in most of those homes. When they weren’t transmitting TV shows, the BBC would sometimes transmit radio programming. Some early TVs included a switch to turn off the video parts of the TV receiver.
Dave Mundy
When I was at Uni. in 1957/8, I remember the Saturday morning stereo tests using TV sound as one channel and Third Programme 464m. MW (!) as the other. Ping-pong sounded great!
Paul Thackray
NICAM was used by the BBC within the Radio distribution to Transmitters, well before there was Stereo TV sound to home use.
The original Stereo Radio experiments were Wrotham – Kent (London only) on the Third Programme only. The LBH to TX was stereo equalised GPO copper wires (as all the mono distribution was). Equalising stereo pairs was a difficult job and not practical for the whole country. The GPO was unable to provide a UK wide stereo distribution network, but had a monopoly on supply.
It was agreed as the GPO (BT) could not supply, the BBC could do its own thing and R&D built a linear (not Nicam) PCM system in the 1960s. This used the remnants of the 405-line TV distribution system as a transport mode. (The 405-line TXs were by now rebroadcasting and converting their local 625 TX). COAX LBH to Swains Lane (North London) then SHF hops North and to Wrotham. Most BBC VHF 405-line sites were the same site as the Radio VHF.
The linear PCM System caried 13 x 15K bandwidth audios and some remote switching. This caried Radio 1/2 (whichever had the TX as it was shared) – 2 audios, Radio 3, 2 Audios, Radio 4 (2 audios) Radio 1, 2, 3, 4 MW/LW in a processed form (compressed, bandwidth limited to 6.5K-ish, carrier tones for line present, opt out in progress, car fax (early RDS) and Electricity board data to phase-modulate the LW carrier to control some experimental ‘Economy 7’ meters. These latter 4 were fed on copper circuits from VHF TXs to their local MW/LW.
3 x 15K audios were routed in to national and some local regions. These could be used for any ad-hoc audio contributions, from full bandwidth interviews to the outgoing side of pres (Presentation) talkback. The bit rate of this system was what was expected to be the agreed world standard, unfortunately something else was agreed by the world, leading to a few issues. A problem of being first!
From the mid-1980s the system was expanded by removing some 13-bit PCM Channels and replacing with NICAM 3 (14 bit companded to 10 bit). This was a bit of a jigsaw, to remove and replace and then move what was on which channel. The eventual system was 24 x 14-bit audios where 13 x 13-bit audios had been.
Radio 3 / BBC TV has a long history of ‘Simulcasts’ The obvious one being the New Year’s Day Concert. In the days of Mono Analog TV and stereo Radio (Analog TX, but digital to TX) it was possible to co-time, so you could watch on TV and listen on Radio 3. It’s still broadcast on TV and Radio with the same presenter, but no longer possible to listen on Radio and view on TV due to the different digital and Satellite delays. It can now be several seconds different, depending on your viewing / listening combination, but not necessary as TV has stereo (and in this case 5.1 sound) available.
[Ed: “companded” – reduced the signal-to-noise ratio of (a signal) using a compander, which is a processor that uses companding (a bit of a circular definition!). “Compander” is a combination of a COMPressor and an exPANDer. The signal is compressed before recording it to tape (which maximizes the signal-to-noise ratio), then expanded as the tape is played back. As the signal is expanded, tape noise effectively is “pushed down,” resulting in a quieter signal.]
Chris Woolf
Indeed, my earlier post was incorrect – it should have been NICAM 3, not 2. NICAM 2 was judged the best system but heavy on bitrate, so was tweaked to NICAM3 to improve that.
