AdvancedA-005-005-001
In an FM phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency, what is the modulation index, when the modulating frequency is 1000 Hz?
B
Answer
Antennas and transmission lines
Type
A
3000
B
3
C
0.3
D
1000
Answer Notes
The modulation index of a Frequency Modulated (FM) signal is a crucial parameter that describes how heavily the carrier is being modulated. It is calculated by comparing the peak frequency deviation to the modulating audio frequency.
The formula for calculating the FM modulation index is: Modulation Index = Maximum Frequency Deviation ÷ Modulating Frequency.
In this scenario, the maximum frequency deviation is 3000 Hz, and the modulating frequency is 1000 Hz. Dividing 3000 by 1000 yields a modulation index of exactly 3.
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