Question

The frequency of local oscillator ________

(a) can be either below or above the RF frequency

(b) is below the RF frequency

(c) is above the RF frequency

(d) is fixed typically at 450KHz

I have been asked this question by my school teacher while I was bunking the class.

My question comes from Bandwidth of FM Signal with Arbitrary m(t) in chapter Angle Modulation of Analog Communications

Answer 1

The correct answer is (c) is above the RF frequency

Explanation: The frequency of the local oscillator is not fixed. It is mostly above the RF frequency.