In video technology, blanking level is the level of the

composite video signal Composite video, also known as CVBS (composite video baseband signal or color, video, blanking and sync), is an analog video format that combines image information—such as brightness (luminance), color (chrominance), and synchronization, int ...

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 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 CCIR System B (originally known as the "Gerber Standard") was the 625-line VHF analog broadcast television system which at its peak was adopted by more than one hundred countries, either with PAL or SECAM colour. It is usually associated with ...

and

CCIR System G CCIR System G, also known as the "Gerber Standard", is an analog broadcast television system used in sixty countries around the world for UHF channels. System G is generally associated with System B for VHF. At a CCIR Geneva meeting in Ju ...

(European systems) and 7.5 IRE units in the case of

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

(American system), although

NTSC-J NTSC-J or "System J" is the informal designation for the analogue television standard used in Japan. The system is based on the US NTSC ( NTSC-M) standard with minor differences. While NTSC-M is an official CCIR and FCCNational Television Sys ...

in Japan, also utilizing System M, uses 0 IRE for both black and blanking much like Systems B & G. 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