Enter the peak frequency deviation and maximum baseband message frequency into the calculator to determine the bandwidth of the FM signal.

Carson’s Rule For Bandwidth Formula

The following formula is used to calculate the bandwidth of a frequency modulated (FM) signal according to Carson’s Rule.

Δf = 2(Δf + fm)

Variables:

  • Δf is the bandwidth of the FM signal (Hz)
  • Δf is the peak frequency deviation (Hz)
  • fm is the maximum baseband message frequency (Hz)

To calculate the bandwidth of the FM signal, add the peak frequency deviation to the maximum baseband message frequency. Multiply the result by 2. This will give you the bandwidth of the FM signal, which represents approximately 98% of the power of the frequency-modulated signal. This formula is crucial for predicting the bandwidth requirements for an FM signal in the design and operation of communication systems.

What is a Carson’s Rule For Bandwidth?

Carson’s Rule is a mathematical formula used to estimate the bandwidth of a frequency modulated (FM) signal. It states that nearly all (~98%) of the power of a frequency-modulated signal lies within a bandwidth of Δf = 2(Δf + fm), where Δf is the peak frequency deviation and fm is the maximum baseband message frequency. The rule provides a simple and reasonably accurate method for predicting the bandwidth requirements for an FM signal, which is crucial for the design and operation of communication systems.

How to Calculate Carson’s Rule For Bandwidth Calculation?

The following steps outline how to calculate Carson’s Rule for Bandwidth Calculation.


  1. First, determine the peak frequency deviation (Δf) in Hz.
  2. Next, determine the maximum baseband message frequency (fm) in Hz.
  3. Next, use the formula Δf = 2(Δf + fm) to calculate the bandwidth of the FM signal (Δf) in Hz.
  4. Finally, calculate the Carson’s Rule for Bandwidth Calculation.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

peak frequency deviation (Δf) = 100 Hz

maximum baseband message frequency (fm) = 50 Hz