NICAM (known also as NICAM 728, after the 728 kbit/s bitstream it is sent over), Near Instantaneous Companded Audio Multiplex, is a format for digital sound on analogue television transmissions. Audio is encoded using 14 bit pulse-code modulation at a sampling rate of 32 kHz. It has been standardized as ETS EN 300 163^[1]. This is a copyrighted and/or trademarked logo. ... This is a copyrighted and/or trademarked logo. ... A bitstream or bit stream is a time series of bits. ... This article is about the unit of information. ... Pulse-code modulation (PCM) is a digital representation of an analog signal where the magnitude of the signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a digital (usually binary) code. ... A kilohertz (kHz) is a unit of frequency equal to 1,000 hertz (1,000 cycles per second). ...

History of NICAM

NICAM was developed in the 80s by the BBC. The first NICAM digital stereo programme was broadcast on the BBC in 1986, though programmes were not advertised as being broadcast in stereo on the BBC until some five years later, when 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. The 1980s refers to the years of 1980 to 1989. ... The British Broadcasting Corporation, usually known as the BBC (and also informally known as the Beeb or Auntie) is the largest broadcasting corporation in the world in terms of audience numbers, employing 26,000 staff in the United Kingdom alone and with a budget of more than GB£4 billion... Label for 2. ...

• The BBC publicly launched their NICAM stereo service in the United Kingdom during 1991 (see 1991 in television) though other UK broadcasters ITV and Channel Four advertised this capability some months earlier.

1991 (MCMXCI) was a common year starting on Tuesday of the Gregorian calendar. ... It has been suggested that Channel 3 (UK) be merged into this article or section. ... Channel 4 is a television broadcaster in the United Kingdom (see British television). ...

Nations using NICAM

Several European countries (as well as one Middle East country) have implemented NICAM with the PAL and SECAM TV systems Television encoding systems by nation PAL, short for Phase Alternating Line, is a colour encoding system used in broadcast television systems in large parts of the world. ... SECAM, also written SÉCAM (Séquentiel couleur à mémoire, French for sequential color with memory), is an analog color television system first used in France. ...

• Belgium
• Denmark
• Finland
• France
• Hungary (Budapest only)
• Iceland
• Ireland
• Israel
• Luxembourg
• Norway
• Poland
• Portugal
• Spain
• Sweden

Sources

1. http://www.ee.surrey.ac.uk/Contrib/WorldTV/broadcast.html
2. http://home.tiscalinet.ch/hahn/atvt.html
3. http://www.videouniversity.com/standard.htm

Some Asia-Pacific nations have implemented NICAM

• Hong Kong (commonly used for dual language for programming containing both Cantonese and English/Mandarin soundtracks)
• South Africa (SABC1, SABC2, etv)
• Malaysia
  • Used by TV1, TV2, ntv7, 8TV, and TV9 around Klang Valley. TV3 also uses NICAM on their VHF transmission frequency (Channel 12) in the Klang Valley.
• New Zealand
  • Used by TVNZ, TV3, C4 and Prime, yet abandoned by Sky-TV's UHF service.

Some other countries use Zweikanalton analog stereo instead. The first RTM logo used from 1957-1963 The second RTM logo used from 1963-1969 The third RTM logo used from 1969-1978 The fourth RTM logo used from 1978-1987 The fifth RTM logo used from 1987-2004 The sixth RTM logo used from 2004-present Radio Televisyen... ntv7 logo Natseven TV Sdn Bhd or better known as NTV7 was launched nationwide on April 7, 1998. ... 8TV (Simplified Chinese: 八度空间; Pinyin: Bā Dù Kōng Jiān) is a private Malaysian television station previously known as Metrovision. ... TV9 is a Malaysian private-owned television station which started transmission on April 22, 2006. ... Sistem Televisyen Malaysia Berhad (STMB) or TV3 was incorporated in 1983 as Malaysia’s first commercial television station. ... Current TVNZ logo Television New Zealand (TVNZ) is the main broadcaster of television in New Zealand, established in 1980 through the merger of Television One and TV2 (formerly South Pacific Television). ... Zweikanalton (two channel sound) is a television sound transmission system used in Germany and other countries. ...

How NICAM works

In order to provide mono "compatibility", the NICAM signal is transmitted on a subcarrier alongside the vision carrier. This means that the FM or AM regular mono sound carrier is left alone for reception by monaural receivers. Monaural (often shortened to mono) sound reproduction is single-channel. ... A subcarrier is separate analog or digital signal carried on a main radio transmission, which carries extra information such as voice or data. ... Frequency modulation (FM) is a form of modulation which represents information as variations in the instantaneous frequency of a carrier wave. ... [[Amplitude modulation]] (AM) is a technique used in electronic communication, most commonly for transmitting information via a carrier wave wirelessly. ...

A NICAM-based stereo-TV infrastructure can transmit a stereo TV programme as well as the mono "compatibility" sound at the same time, or can transmit two or three entirely different sound streams. This latter mode could be used to transmit audio in different languages, in a similar manner to that used for in-flight movies on international flights. In this mode, the user can select which soundtrack to listen to when watching the content by operating a "sound-select" control on the receiver.

Image File history File links NICAM-spectrum. ...

NICAM currently offers the following possibilities. The mode is auto-selected by the inclusion of a 3-bit type field in the data-stream

• One digital stereo sound channel.
• Two completely different digital mono sound channels.
• One digital mono sound channel and a 352 kbit/s data channel.
• One 704 kbit/s data channel.

The four other options could be implemented at a later date. Only the first two of the ones listed are known to be in general use however.

NICAM packet transmission

The NICAM packet (except for the header) is scrambled with a nine-bit pseudo-random bit-generator before transmission.

• The topology of this pseudo-random generator yields a bitstream with a repetition period of 511 bits.
• The psudo-random generator's polynomial is: x^9 + x^4 + 1.
• The psudo-random generator is initialized with: 111111111.

Making the NICAM bitstream look more like white noise is important because this reduces signal patterning on an adjacent TV channels. White noise spectrum White noise( ) is a random signal (or process) with a flat power spectral density. ...

• The NICAM header is not subject to scrambling. This is necessary so as to aid in locking on to the NICAM data stream and resynchronisation of the data stream at the receiver.
• At the start of each NICAM packet the pseudo-random bit generator's shift-register is reset to all-ones.

NICAM transmission issues

Image File history File links NICAM-spectrum-PAL_B_G.png‎ NICAM spectrum as implimented with PAL TV systems B and G. This is historical documentation of the NICAM system. ...

There are some latent issues involved with the processing of NICAM audio in the transmission chain.

• NICAM (unlike the compact disc standard) samples 14 bit audio at 32 khz.
• The upper frequency limit of a NICAM sound channel is 15 kHz due to anti-aliasing filters at the encoder.
• The original 14 bit PCM audio samples are companded digitally to 10 bits for transmission.
• NICAM audio samples are divided into blocks of 32. If all the samples in a block are quiet, such that the most significant bits are all zeros, these bits can be discarded at no loss.
• On louder samples some of the least significant bits are truncated, with the hope that they will be inaudible.
• A 3-bit control signal for each block records which bits were discarded.
• Digital companding (using a CCITT J.17 pre-emphasis curve) ensures that the encoding and decoding algorithms can track perfectly.

The binary representation of decimal 149, with the MSB highlighted. ... The binary representation of decimal 149, with the lsb highlighted. ...

NICAM carrier power

ITU (and CCITT) standards specify that the power level of the NICAM signal should be at -20 dB with respect to the power of the vision carrier.

• The level of the FM mono sound carrier must be at least -13 dB.
• Measuring the modulation level of the NICAM signal is difficult because the QPSK NICAM carrier waveform (unlike AM or FM modulated carrier waveforms) is not emitted at a discrete frequency.

When measured with spectrum analyzer the actual level of the carrier (L) can be calculated using the following formula:

L(NICAM) = L(Measured) + 10 log (R/BWAnalyzer) + K

1. L(NICAM) = actual level of the NICAM carrier [dBμV]
2. L(Measured) = measured level of the NICAM carrier [dBμV]
3. R = -3 dB bandwidth of the signal [kHz]
4. BWAnalyzer = bandwidth of the spectrum analyzer [kHz]
5. K = logarithmic form factor of the spectrum analyzer ~2 dB

NICAM's unusual features

NICAM sampling is not standard PCM sampling, as commonly employed with the Compact Disc or at the codec level in MP3, AAC or Ogg audio devices. NICAM sampling more closely resembles Adaptive Pulse Code Modulation. PCM is an initialism which can have different meanings: Phase Change Material Pulse-code modulation, a way to digitally encode signals representing sound and their video counterparts Potential Cancer Marker Communist Party of Mexico Plug Compatible Manufacturer Power-train control module, a computer in a car which controls the car... This article or section does not cite its references or sources. ... MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a popular digital audio encoding, lossy compression format, and algorithm, designed to greatly reduce the amount of data required to represent audio, yet still sound like a faithful reproduction of the original uncompressed audio to most listeners. ... Advanced Audio Coding (AAC) is a standardized, lossy compression and encoding scheme for digital audio. ... Look up Ogg in Wiktionary, the free dictionary. ...

Two's complement signing

The two's complement method of signing the samples is used,^[2] so that: Twos complement is the most popular method of representing signed integers in computer science. ...

• 01111111111111 represents positive full-scale
• 10000000000000 represents negative full-scale

±0v has three binary representations

• 00000000000001 represents 0V, with no +/- distinction. This may have originated as a method to reduce the emergence of DC patterns from transmission of silent material.
• 00000000000000 represents 0V, with no +/- distinction
• 11111111111111 represents 0V, with no +/- distinction

Hidden services

NICAM's STL link capability

• http://tallyho.bc.nu/~steve/nicam.html#SPARE

Parity checking limited to only 6 of 10 bits

In order to strengthen parity protection for the sound samples, the parity bit is calculated on only the top six bits of each NICAM sample. Early BBC NICAM research showed that uncorrected errors in the least significant four bits were preferable to the reduced overall protection offered by parity-protecting all ten bits.

VHS recording of NICAM audio

As far as NICAM-capable video cassette recorders are concerned, the common practice is to record the NICAM-derived stereo stream on the VHS Hi-Fi tracks while the mono compatibility signal is recorded on the linear track. The video cassette recorder (or VCR, less popularly video tape recorder) is a type of video tape recorder that uses removable cassettes containing magnetic tape to record audio and video from a television broadcast so it can be played back later. ... Bottom view of VHS cassette with magnetic tape exposed Top view of VHS cassette with front casing removed The Vertical Helical Scan, better known by its abbreviation VHS (and often confused to be Video Home System) is a recording and playing standard for analog video cassette recorders (VCRs), developed by...

References

1. ^ ETSI ETS EN 300 163, (previously: EBU T 3266 )
2. ^ http://tallyho.bc.nu/~steve/nicam.html

See also

• Multichannel television sound
• Sound-in-Syncs
• Zweikanalton A2

Multichannel television sound, better known as MTS (often still as BTSC, for the Broadcast Television Systems Committee that created it), is the method of encoding three additional channels of audio into an NTSC-format audio carrier. ... Sound-in-Syncs is a method of multiplexing sound and video signals into a channel designed to carry video, in which data representing the sound is inserted into the line synchronising pulse of an analogue TV waveform. ... Zweikanalton (two channel sound) is a television sound transmission system used in Germany and other countries. ...

External links

• A technical description of NICAM
• The BBC's information page on NICAM
• Overview of Television Broadcasting Systems