In India for broadcasting TV programmes which system is followed ?

Question

Accepted Answer

Correct answer: B — Concept: A colour-television broadcasting system is fixed by two things together: the monochrome scanning standard, which sets the number of lines per frame and the field rate and is tied to the mains supply frequency, and the colour-encoding method that adds the chrominance information to that scanned signal. Only three analogue colour-encoding methods were ever standardised worldwide, and each country adopts one of them along with its scanning standard. Application: India's terrestrial television service, operated by Doordarshan, uses the 625-line, 50 Hz scanning standard (CCIR System B on VHF and System G on UHF), and when colour transmission began in 1982 the colour-encoding method adopted with it was PAL, that is Phase Alternating Line. The Indian system is accordingly designated PAL-B and PAL-G. In PAL the phase of one colour-difference component is reversed on every alternate line, so a phase error picked up along the transmission path is averaged out between two successive lines and the reproduced hue stays stable. Cross-check — the three analogue colour systems: System How the colour information is carried Scanning standard and typical users NTSC Both colour-difference signals amplitude-modulate a single subcarrier, and hue is carried by the phase of that subcarrier, so a phase error on the path shifts the reproduced hue. 525 lines, 60 Hz — North America, Japan PAL The phase of one colour-difference component is inverted line by line, so a phase error is cancelled between two successive lines. 625 lines, 50 Hz — India, most of Europe, Australia SECAM The two colour-difference signals are frequency-modulated and sent on alternate lines, so the receiver holds one line in a delay memory to rebuild the pair. 625 lines, 50 Hz — France, Russia, parts of Africa The two remaining labels are not television systems at all: NTCS is a transposition of the letters of NTSC, and NTSE stands for the National Talent Search Examination. Result: The system followed in India for broadcasting TV programmes is PAL.

Answer

A. NTCS

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B. PAL

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C. NTSE

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D. SECAM

System	How the colour information is carried	Scanning standard and typical users
NTSC	Both colour-difference signals amplitude-modulate a single subcarrier, and hue is carried by the phase of that subcarrier, so a phase error on the path shifts the reproduced hue.	525 lines, 60 Hz — North America, Japan
PAL	The phase of one colour-difference component is inverted line by line, so a phase error is cancelled between two successive lines.	625 lines, 50 Hz — India, most of Europe, Australia
SECAM	The two colour-difference signals are frequency-modulated and sent on alternate lines, so the receiver holds one line in a delay memory to rebuild the pair.	625 lines, 50 Hz — France, Russia, parts of Africa