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In the context of radio receivers, what does the term 'selectivity' refer to?

Difficulty: Easy

Correct Answer: Its ability to reject adjacent unwanted signals

Explanation:


Introduction / Context:
Selectivity is a key parameter of a radio receiver, describing how well it can isolate the desired station while rejecting signals on nearby frequencies. This property is vital in crowded frequency bands where stations are closely spaced.


Given Data / Assumptions:

  • Receiver tuned to one frequency f_s.
  • Nearby stations transmit at f_s ± Δf.
  • Filters and tuned circuits determine selectivity.


Concept / Approach:
Good selectivity means the receiver can attenuate signals just outside the passband while allowing the tuned frequency through with minimal loss. It is primarily a function of the Q-factor of tuned circuits and IF filter characteristics.


Step-by-Step Solution:

Receiver tuned to 1000 kHz station.Adjacent station at 1005 kHz.High selectivity ensures only 1000 kHz is amplified and demodulated.Low selectivity would cause overlap and interference.


Verification / Alternative check:

Selectivity curves show bandwidth narrowing to reject adjacent signals.


Why Other Options Are Wrong:

Amplifying weak signals describes sensitivity, not selectivity.Maximum amplification frequency is resonance, not selectivity.Noise suppression is related to SNR, not selectivity.Demodulating multiple signals simultaneously is not the role of selectivity.


Common Pitfalls:

Confusing sensitivity with selectivity; both are critical but distinct receiver parameters.


Final Answer:

Its ability to reject adjacent unwanted signals
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