All radios will need a sufficiently high level of image rejection, and this is provided by:

Question

Question

This question was previously asked in

DFCCIL Executive S&T 29 Sept 2021 Official Paper

Answer 1

Super-heterodyne receiver

in amplifier no change of frequency is done. Only signal strength is increased.

It is used in mainly radio and Tv.

F2 S.B 6.8.20 Pallavi D17

Image frequency: The signal which causes interference is called ‘image frequency’

Image frequency and intermediate frequency related as:

fsi = fs + IF

fs: carrier frequency of the tuned station

fsi: image frequency

IF: Intermediate frequency

The image rejection ratio of the receiver is given by:

\(\alpha = \sqrt {1 + {P^2}Q_1^2} .\sqrt {1 + {P^2}Q_2^2} \)

\(P = \frac{{{f_{si}}}}{{{f_s}}} - \frac{{{f_s}}}{{{f_{si}}}}\)

For a high quality factor amplifier, IRR can be approximated as:

\(\alpha \approx {P^2}{Q_1}{Q_2}\)

In terms of the operation of the super-heterodyne receiver, the front end RF tuning circuit is required to remove the image signal.

F1 Neha Madhuri 20.11.2021 D4