Gaussian Frequency-shift Keying - Generalization

Generalization

A GFSK modulator, is similar to a FSK modulator, except that before the baseband pulses (−1, +1) go into the FSK modulator, it is passed through a gaussian filter to make the pulse smoother so to limit its spectral width. Gaussian filtering is one of the very standard ways for reducing the spectral width, it is called "pulse shaping".

If we use −1 for and +1 for, once when we jump from −1 to +1 or +1 to −1, the modulated waveform changes rapidly, which introduces large out-of-band spectrum. If we change the pulse going from −1 to +1 as −1, −.98, −.93 ..... +.96, +.99, +1, and we use this smoother pulse to modulate the carrier, the out-of-band spectrum will be reduced.