Editing NICAM (section)

== History ==
=== Near-instantaneous companding ===
The idea was first described in 1964. In this, the 'ranging' was to be applied to the analogue signal before the [[Analog-to-digital converter|analogue-to-digital converter (ADC)]] and after the [[Digital-to-analog converter|digital-to-analogue converter (DAC)]].<ref>Bartlett, C.J.C. and Greszczuk, J. (1964), ''Companding in a p.c.m. system''. Symposium on Transmission Aspects of Communication Networks, London, IEE 1964, pp. 183–186.</ref> The application of this to broadcasting, in which the [[companding]] was to be done entirely digitally after the ADC and before the DAC, was described in a 1972 [[BBC Research]] Report.<ref>Osborne, D.W. (1972) [http://www.bbc.co.uk/rd/publications/rdreport_1972_31 ''Digital sound signals: further investigation of instantaneous and other rapid companding systems''.] BBC Research Dept. Report 1972/31.</ref>

=== Point-to-point links ===
NICAM was originally intended to provide broadcasters with six high-quality audio channels within a total [[Bandwidth (computing)|bandwidth]] of 2048&nbsp;kbit/s. This figure was chosen to match the [[E-carrier level 1|E1]] primary [[Multiplexing|multiplex]] rate, and systems using this rate could make use of the planned [[Plesiochronous Digital Hierarchy|PDH]] national and international telecommunications networks.

Several similar systems had been developed in various countries, and in about 1977/78 the [[BBC Research|BBC Research Department]] conducted listening tests to evaluate them. The candidates were:
* A [[RAI]] system which used [[A-law]] companding to compress 14-bit [[Pulse-code modulation|linear PCM]] [[sampling (signal processing)|samples]] into 10 bits (14:10)
* A NICAM-type system proposed by [[Télédiffusion de France]] (14:9)
* NICAM-1 (13:10)
* NICAM-2 (14:11)
* NICAM-3 (14:10)

It was found that NICAM-2 provided the best sound quality, but reduced programme-modulated noise to an unnecessarily low level at the expense of bit rate. NICAM-3, which had been proposed during the test to address this, was selected as the winner.<ref name="jones">Jones, A.H. (1978), ''Digital coding of audio signals for point-to-point transmission''. IEE Conference Publication No. 166, pp. 25–28</ref><ref>Gilchrist, N.H.C. (1978), [http://www.bbc.co.uk/rd/publications/rdreport_1978_26 ''Digital sound signals: tests to compare the performance of five companding systems for high-quality sound signals''.] BBC Research Department Report 1978/26.</ref>

Audio is encoded using 14 [[bit]] [[pulse-code modulation]] at a sampling rate of 32 [[kHz]].

=== Broadcasts to the public ===

NICAM's second role – transmission to the public – was developed in the 80s by the [[BBC]]. This variant was known as NICAM-728, after the 728&nbsp;kbit/s [[bitstream]] it is sent over. It uses the same audio coding parameters as NICAM-3.

The first NICAM digital [[stereophonic sound|stereo]] programme was the [[The Proms|First Night of the 92nd edition of the Proms]] which was broadcast on BBC2 from the [[Crystal Palace transmitting station]] in London on 18 July 1986, though programmes were not advertised as being broadcast in stereo on the BBC until Saturday 31 August 1991, by which time the majority of the country's transmitters had been upgraded to broadcast NICAM, and a large number of BBC programmes were being made in stereo. coming as many as 18 months after [[ITV (TV network)|ITV]] and [[Channel 4]] had begun advertising this capability to coincide with the [[Independent Broadcasting Authority]] rolling out NICAM on a transmitter-by-transmitter basis which had begun in 1989 with the Crystal Palace and [[Emley Moor transmitting station|Emley Moor]] transmitters.<ref>[https://www.youtube.com/watch?v=f9-bnNFPArI&ab_channel=bayside2000  IBA Engineering Announcement 19 December 1989]</ref>

It has been standardized as ETS EN 300 163.<ref>[http://www.etsi.org/ ETSI] ETS EN 300 163, (previously: [http://www.ebu.ch EBU] T 3266)</ref>

==== Nations and regions using NICAM public broadcasts ====
Several European countries had implemented NICAM with the [[PAL]] and [[SECAM]] TV systems<ref>{{cite web|url=http://www.ee.surrey.ac.uk/Contrib/WorldTV/broadcast.html |title=Broadcasting System Details |publisher=University of Surrey – Department of Electronic Engineering |access-date=2007-08-30 |url-status=dead |archive-url=https://web.archive.org/web/20101205071827/http://www.ee.surrey.ac.uk/Contrib/WorldTV/broadcast.html |archive-date=December 5, 2010 }}</ref><ref>[http://home.tiscalinet.ch/hahn/atvt.html Analogue TV technologies]</ref><ref>[http://www.videouniversity.com/standard.htm World-Wide T.V. Standards]</ref>
* [[Belgium]] (analogue cable systems only; terrestrial switched to [[DVB-T]])
* [[Croatia]] (historical, switched to DVB-T and later DVB-T2, analog cable seems to either be mono or use analog A2 stereo)
* [[Denmark]] (historical, switched to DVB-T and DVB-C)
* [[Estonia]] (historical, switched to DVB-T and DVB-C)
* [[Finland]] (historical, switched to DVB-T and DVB-C)
* [[France]] (historical, switched to DVB-T)
* [[Greece]] ([[ANT1]], [[New Hellenic Television]], [[ET3 (Greece)|ET3]] and [[ET1 (Greece)|ET1]] - historical, switched to DVB-T)
* [[Hungary]] (historical, switched to DVB-T)
* [[Iceland]] (historical, switched to DVB-T)
* [[Republic of Ireland|Ireland]] (historical, switched to DVB-T. Analogue cable channels may still carry NICAM audio. However, these are digitally sourced channels re-encoded as PAL with NICAM at the headend.)
* [[Luxembourg]] (switched to DVB-T; cable?)
* [[Norway]] (historical, switched to DVB-T and DVB-C)
* [[Poland]] (Analogue cable systems only; terrestrial switched to DVB-T)
* [[Portugal]] (historical, switched to DVB-T)
* [[Romania]] (historical on terrestrial as switched to DVB-T2; on cable networks, still used by some operators providing analogue cable television)
* [[Russia]]
* [[Spain]] (historical, switched to DVB-T)
* [[South Africa]] ([[SABC 1]], [[SABC 2]], [[e.tv]])
* [[Sweden]] (historical, switched to DVB-T and DVB-C)
* [[Ukraine]]
* [[United Kingdom]] (historical, switched to DVB-T)

Some Asia-Pacific nations and regions have implemented NICAM
* [[China]]
** [[Hong Kong]] (commonly used for dual language for programming containing both Cantonese and English/Mandarin/Japanese/Korean soundtracks; full switchover to [[Digital Terrestrial Multimedia Broadcast|DTMB]] with Dolby AC-3 audio encoding complete by 1 December 2020, NICAM became historical from that date)
** [[Macau]] (commonly used for dual language for programming containing both Cantonese and Portuguese/English/Mandarin/Japanese/Korean soundtracks; full switchover to DTMB with MPEG-1 Audio Layer II audio encoding complete by 30 June 2023, NICAM became historical from that date)
* [[Malaysia]]
** Formerly used by [[Radio Televisyen Malaysia|TV1, TV2]], [[ntv7]], [[8TV (Malaysia)|8TV]], and [[TV9 (Malaysia)|TV9]] around Klang Valley. [[TV3 (Malaysia)|TV3]] also used NICAM on their VHF transmission frequency (Channel 12) in the Klang Valley, but used Zweikanalton on their UHF transmission frequency (Channel 29). Analog shutdown complete by 1 January 2019, thus NICAM and Zweikanalton broadcast became historical from that date.
* [[New Zealand]] (Full switchover to DVB-T complete by 1 December 2013. NICAM became historical from that date.)
* [[Indonesia]]
** Most national television networks in Indonesia used NICAM for analogue television. Analog shutdown complete by August 12, 2023, thus NICAM became historical from that date.
* [[Singapore]] (Used on [[Mediacorp Channel U]]. Full switchover to DVB-T2 complete by 1 January 2019. NICAM became historical from that date.)
* [[Sri Lanka]]
* [[Thailand]]
** Used on [[Channel 3 (Thailand)|Channel 3]], [[Channel 9 MCOT HD]] and [[Thai Public Broadcasting Service|Thai PBS]], usually broadcast in dual-sound mode with sometimes in stereo mode. All analogue television service ceased since March 26, 2020. Switchover to terrestrial [[DVB-T2]] with HE-AAC v2 codec, NICAM became historical from that date.
Some other countries use [[Zweikanalton]] analogue stereo instead. Analogue stereo conversion thus begins.