Question

________ separates video signal from composite signal.

• A. Duplexer
• B. Sync separator
• C. Diode detector
• D. High power amplifier

Hint:

The Diode detector acts as the video demodulator in an analog TV receiver, converting the high-frequency intermediate frequency (IF) signal back into the baseband composite video signal.

Answer 1

The Correct Option is C

Step 1: Analyzing the Composite Video Signal:
The composite video signal contains picture information (luminance and chrominance), blanking pulses, and synchronization pulses (horizontal and vertical sync) modulated onto the picture IF carrier.

Step 2: Demodulation and Separation:
To retrieve the raw composite video signal from the modulated intermediate frequency (IF) carrier, the signal is passed through a Diode detector (envelope detector).

• The diode rectifies the high-frequency IF signal.
• A low-pass RC filter bypasses the high-frequency carrier ripples to ground, leaving behind the demodulated composite video signal.

Step 3: Comparing with Sync Separator:
The sync separator (B) is used after the diode detector. It isolates the synchronization pulses from the composite video signal to sync the sweep circuits, rather than separating the video signal from the modulated carrier.

Step 4: Conclusion:
Therefore, the Diode detector is the component that extracts (separates) the video signal from the modulated carrier, making option (C) correct.