CCIR System B

A first 625-line system with a 8 MHz channel bandwidth was proposed at the CCIR Conference in Stockholm in July 1948 (based on 1946-48 studies in the Soviet Union[6] by Mark Krivosheev[7][8][9][10][11][12][13]).

[3] At a CCIR Geneva meeting in July 1950 Dr. Gerber (a Swiss engineer), proposed a modified 625-lines system with a 7 MHz channel bandwidth (based on work by Telefunken and Walter Bruch), with the support of Belgium, Denmark, Italy, Netherlands, Sweden, Switzerland.

[6] Known as the "Gerber-norm", it was eventually approved along with four other broadcast standards on the next formal CCIR meeting in May 1951 in Geneva.

It is mostly replaced across Western Europe, former Yugoslavia, parts of Asia and Africa by digital broadcasting.

The polarity of modulation is negative, meaning that an increase in the instantaneous brightness of the video signal results in a decrease in RF power and vice versa.

Specifically, the sync pulses (being "blacker than black") result in maximum power from the transmitter.

The total RF bandwidth of System B (as originally designed with its single FM audio subcarrier) was 6.5 MHz, allowing System B to be transmitted in the 7.0 MHz wide channels specified for television in the VHF bands with an ample 500 kHz guard zone between channels.

[18] In specs, sometimes, other parameters such as vestigial sideband characteristics and gamma correction of the display device are also given.

(This behaviour would cause massive U/V crosstalk in the NTSC system, but delay-line PAL hides such artefacts.)

The introduction of Zweikanalton in 1981 allowed for stereo sound or twin monophonic audio tracks (possibly in different languages for instance).

Alternatively, starting in the late 1980s and early 1990s it became possible to replace the second audio FM subcarrier with a digital signal carrying NICAM sound.

The European 41-68 MHz Band I television allocation was agreed at the 1947 ITU (International Telecommunication Union) conference in 1947, and the first European channel plan (i.e. the use of channels E2 - E4) was agreed in 1952 at the ITU conference in Stockholm.

‡ Channels 3, 4 and 5 were scheduled to be cleared during 1993–96 to make way for FM radio stations in Band II.

This makes much better use of the 8.0 MHz channels of the UHF bands (though whether any system B/H televisions actually made use of the extra bandwidth is not known).