# Calculation of bandwidth in FM using Carson’s rule

## What is the required bandwidth according to the Carson’s rule, when a 100 MHz carrier is modulated with a sinusoidal signal at 1KHz, the maximum frequency deviation being 50 KHz.

**Options:**

(a) 1 KHz

(b) 50 KHz

(c) 102 KHz

(d) 150 KHz

Correct Answer: 102 KHz

**Explanation: **

According to Carson’s rule, bandwidth of FM is given by 2(Δf+ fm) where Δf is the deviation in frequency and fm is the frequency of sinusoidal signal. The required bandwidth is therefore calculated as

2* (50KHz + 1KHz)

= 2 * 51 KHz

= 102 KHz