Match communication systems/receivers to their characteristic techniques. List I List II A. Costas receiver 1. Vestigial sideband (VSB) B. Stereo multiplexing (radio) 2. Demodulating DSB-SC (coherent) C. TV broadcasting 3. FM radio broadcasting (multiplex)

Introduction / Context:
Different communication services use different modulation/detection methods. Matching them quickly is a staple of communications examinations and interviews.

Given Data / Assumptions:

• Costas loop is a coherent detector for DSB-SC or suppressed-carrier systems.
• FM stereo broadcasting uses multiplexing (L+R, L−R with a pilot).
• Analog TV broadcasting traditionally used AM-VSB for the video channel.

Concept / Approach:

Map each system to the defining modulation/detection method: Costas→DSB-SC demodulation, stereo multiplex→FM radio system, TV broadcast→VSB to reduce bandwidth while maintaining low-frequency fidelity.

Step-by-Step Solution:

Verification / Alternative check:

Block diagrams in standard texts show Costas loops recovering carrier phase; FM stereo multiplex standards (e.g., 75 kHz deviation, pilot) validate B; NTSC/PAL video spectrum masks show VSB, confirming C.

Why Other Options Are Wrong:

• Assigning VSB to FM stereo is incorrect; FM multiplex does not use vestigial sidebands.
• Claiming Costas is for VSB confuses coherent DSB-SC detection with amplitude filtering techniques.

Common Pitfalls:

Mixing up Costas with a simple envelope detector; the latter requires an unsuppressed carrier and is not suitable for DSB-SC.

Final Answer:

A-2, B-3, C-1