In video technology, blanking level is the level of the

composite video signal Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two chann ...

during the front and back porches of the video signal. The composite video signal is actually the video information superimposed on blanking. The total level of the composite video signal (blanking + video) is 1000 mV. This level can also be given in

IRE Ire or IRE may refer to: Ire * Extreme anger; intense fury * Irē, the Livonian name for Mazirbe, Latvia * A town in Oye, Nigeria * ''Ire'' (album), a 2015 album by the Australian metalcore band Parkway Drive * Ire (Iliad), a town mentioned in t ...

units such that the level difference reserved for video information is 100 IRE units. So white corresponds to 100 IRE units and blanking level corresponds to 0 IRE units. The level of black is 0 IRE units in the case of CCIR System B and CCIR System G (European systems) and 7.5 IRE units in the case of

CCIR System M CCIR System M, sometimes called 525–line, monochrome NTSC or NTSC-M, is the analog broadcast television system approved by the FCC (upon recommendation by the National Television Systems Committee - NTSC) for use in the United States sin ...

(American system).Kolumbus page
/ref> So, while there is no difference between the black and the blanking levels in most systems, they differ by 50 mV in system M. (When defined in terms of voltage difference, 7.5 IRE units is almost equal to 50 mV.)

References

{{Analogue TV transmitter topics Television technology Broadcast engineering