Distrortion Produced by Band Limitation of an FM Wave

When a frequency-modulated wave passes through a filter, distortion is produced in the signal by nonlinearity in the filter phase shift (usually the chief offender) and by the filter attenuation. Much effort has been spent in devising methods for computing this distortion. A related problem is "What radio frequency bandwidth is required to transmit a given FM wave?" An approximate answer, known as "Carson's rule," states that the required bandwidth 2/>, is given by 1 2 fh = 2 B + 2D max , 605 (1)