Mumbai University > Electronics Engineering > Sem4 > Fundamentals of Communication Engineering

Marks: 4M

Year: May 2015

1. Theoretically, the bandwidth of the FM wave is infinite. But practically, it is calculated based on how many sidebands have significant amplitude

2. The simplest method to calculate the bandwidth

   B.W. = 2fm x Number of significant sidebands

3. With increase in modulation index, the number of significant sidebands increase. This will increase the bandwidth

Carson’s Bandwidth

1. The second method to find the practical bandwidth is a rule of thumb. It states that the bandwidth of FM wave is twice the sum of the deviation and the highest modulation frequency.

   ∴ BW = 2 [ $ δ+f_{m(max)}$]

2. The Carson’s rule gives correct results if the modulation index is greater than 6.