Question

Which is true in a frequency modulated system ?
1. Variation of carrier amplitude does not affect quality of reception
2. Amplitude of carrier is varied according to modulating signal
3. The transmission does not require line of sight between transmitter and reciever
4. Receiver uses diode detector

Answer 1

Correct Answer - Option 1 : Variation of carrier amplitude does not affect quality of reception

Frequency Modulation:

• Frequency Modulation is a modulation in which the frequency of the carrier wave is altered according to the instantaneous amplitude of the modulating signal, keeping phase and amplitude constant.
• So, the variation in carrier amplitude and carrier phase does not affect the signal in the receiving end.
• Line of sight (LoS) is a type of propagation that can transmit and receive data only where transmit and receive stations are in view of each other without any sort of an obstacle between them. Eg: FM radio, microwave, and satellite transmission.
• Frequency Modulation works on the Line of sight propagation.

Types of FM detection:

• Slope detection
• Phase-locked loop detection
• Foster Seeley detection
• Ratio detector
• Quadrature detectors.