# Carson’s rule for calculation of bandwidth of FM signal

## Carson’s rule is used to calculate

**Options:**

Bandwidth of FM signal

Signal to noise ratio

Modulation index

Noise figure

Correct Answer: Bandwidth of FM signal

**Explanation: **

According to Carson’s rule, the bandwidth required is twice the sum of the maximum frequency deviation and the maximum modulating signal frequency. Or,

B=2(Δf +f_{m}) Hz.

## The ratio of maximum peak frequency deviation and the maximum modulating signal frequency is termed as

**Options:**

Frequency deviation

Deviation ratio

Signal to noise ratio

Frequency spectrum

Correct Answer: Deviation ratio

**Explanation: **

In Frequency Modulation, Deviation ratio is the ratio of maximum peak frequency deviation and the maximum modulating signal frequency. Mathematically, the Deviation Ratio (DR) is given by

DR= Δf _{(max) }/f_{m (max)}