OBSERVATION

The Chief Examiner reported thatvery many candidates avoided this question. Those who responded to it could NOT list the difference between the monochrome and color TV receivers. And many did not recall the frequency for horizontal and vertical oscillators as well as the sub- and inter-carriers. Only a few candidates, according to the report, correctly listed the secondary colors (cyan, magenta, yellow) of color TV technology.

The expected responses were:

• Differences between monochrome and colour television receivers

(i) Monochrome Television Receiver has one electron gun whilst the colour television
has three electron guns.

(ii) Monochrome Television receiver has a single raster whilst colour television has
threerasters.
(iii) Monochrome television receiver has a single video signal whilst a colour
television receiver has two video signals (luminance and chrominance signals)
(iv) Monochrome TV receiverhas no colour burst signal whilst the colour TV
receiver has colour burst signal

• (i) Horizontal Oscillator          -           15625Hz

(ii) Vertical Oscillator             -                50 Hz
(iii) Sub carrier            -          4.43 MHz
(iv) Inter carrier sand              -               6 MHz

(c) Secondary colours used in colour television receivers

• Cyan
• Magenta
• Yellow