Q.Explain the following characteristics of a radio receiver. a) Sensitivity b) Selectivity c) Fidelity

Sensitivity, selectivity and fidelity are three basic performance measures of a radio receiver. Sensitivity is its ability to receive weak signals, selectivity its ability to reject unwanted stations, and fidelity its ability to reproduce the original signal faithfully. …

[!TLDR]

Sensitivity = ability to receive weak signals; selectivity = ability to reject unwanted signals; fidelity = ability to reproduce the signal faithfully.

a) Sensitivity: The sensitivity of a receiver is its ability to amplify and reproduce very weak signals. It is measured as the minimum radio-frequency input signal (usually expressed in microvolts) required at the antenna to produce a specified standard output power with a specified signal-to-noise ratio. A receiver with high sensitivity needs only a small input and can therefore receive weak and distant stations. Sensitivity is determined mainly by the gain of the RF and IF amplifier stages.

b) Selectivity: The selectivity of a receiver is its ability to select the desired signal frequency while rejecting the unwanted signals of nearby (adjacent) channels. It depends on the sharpness of the response of the tuned circuits, that is, on their quality factor Q. Good selectivity means the receiver passes the wanted station and its side bands but strongly attenuates neighbouring stations, so there is no interference between channels. …