Question

The intermediate frequency of a super-heterodyne receiver is 450 KHz. If it is tuned to 1200 KHz, the image frequency will be
1. 750 KHz
2. 900 KHz
3. 1600 KHz
4. 2100 KHz

Answer 1

Correct Answer - Option 4 : 2100 KHz

Concept:

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

Image frequency and intermediate frequency related as:

fsi = fs + 2 IF

fs: carrier frequency of the tuned station

fsi: image frequency

IF: Intermediate frequency

Calculation:

Given intermediate frequency (I.F) = 450 KHz

Tuned signal frequency is fs = 1200 KHz

Image frequency is

fsi = 1200 KHz + 2 × 450 KHz

fsi = 1200 kHz + 900 kHz

fsi = 2100 KHz