Superheterodyne Receiver Blocks: Match Each Stage to Its Role List I (Stage) A. RF amplifier B. Loudspeaker C. Demodulator D. IF amplifier List II (Function) Amplifies received carrier along with its sidebands (preselects front-end) Provides acoustic (audio) output Accepts IF input and delivers AF (baseband) output by detection Fixed-tuned amplification at the intermediate frequency
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AA-1, B-2, C-3, D-4
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BA-2, B-1, C-3, D-4
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CA-3, B-4, C-1, D-2
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DA-1, B-4, C-3, D-2
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EA-4, B-2, C-1, D-3
Answer
Correct Answer: A-1, B-2, C-3, D-4
Explanation
Introduction / Context:Superheterodyne receivers divide processing into RF front-end filtering/amplification, frequency conversion to a fixed IF, selective amplification, and baseband detection, finally driving an audio transducer. Knowing each block's role is foundational for radio design and troubleshooting.
Given Data / Assumptions:
- RF amplifier precedes the mixer, improving sensitivity and selectivity.
- IF amplifier operates at a fixed intermediate frequency with narrowband selectivity.
- Demodulator recovers the audio/baseband (AF) from IF.
- Loudspeaker converts electrical AF to sound.
Concept / Approach:
Assign each stage to the description that best matches its standard function within a superhet architecture.
Step-by-Step Solution:
A (RF amplifier) → boosts incoming RF signal and rejects out-of-band interference ⇒ 1.B (Loudspeaker) → transduces AF signal to acoustic output ⇒ 2.C (Demodulator) → accepts IF and outputs AF (AM/FM/SSB detector depending on design) ⇒ 3.D (IF amplifier) → provides high, fixed-frequency gain and selectivity ⇒ 4.Verification / Alternative check:
Standard block diagrams of AM/FM superhet receivers confirm: antenna → RF amp → mixer/LO → IF filter/amp → detector → AF amp → loudspeaker.
Why Other Options Are Wrong:
Swapped mappings would misplace functions (e.g., a loudspeaker cannot amplify IF, and an IF amplifier does not produce audio). RF amplification must precede conversion to preserve signal quality.
Common Pitfalls:
Confusing RF and IF roles, or assuming the demodulator operates directly at RF; while direct-conversion radios exist, this question clearly targets superheterodyne architecture.
Final Answer:
A-1, B-2, C-3, D-4