This page covers comparison between GFSK and FSK modulation techniques with respect to various system parameters. Following are difference between GFSK and FSK modulation types.


FSK modulation

FSK stands for Frequency Shift Keying. FSK modulation technique is used to modulate binary string of 1's and 0's suitable for transmission using RF carrier frequency from one end to the other end.

Example of simple FSK scheme is Binary FSK. In BFSK, binary information of 1 and 0 is represented by change of frequency e.g. binary 1 is represented by frequency f1 and binary 0 is represented by frequency f2. Refer what is modulation page for types of modulation viz. analog and digital. The basic digital modulation types include ASK,FSK and PSK.

FSK modulation spectral width is unlimited. In FSK, fc will jump sharp to fd. This decreases spectral efficiency to a great extent. Continuous phase FSK modulation having index of 0.5 is referred as MSK modulation.
Refer 2FSK vs 4FSK modulation types >>.


GFSK stands for Gaussin Frequency Shift Keying modulation. In GFSK, baseband pulses (consists of -1 and 1) are first passed through the gaussian filter before modulation. This makes pulses smooth and hence limit the modulated spectrum width. This process is known as pulse shaping.

In GFSK, spectral width is limited due to filter. Here fc climbs slowly and will attain value equal to fd. Bluetooth radio chip employs the GFSK modulation type.
Also refer GMSK modulation.

Useful Links

what is modulation
MSK and GMSK modulation
BPSK modulation
8-PSK modulation
QPSK modulation
QAM modulation
BPSK vs QPSK -Difference Between BPSK and QPSK modulation techniques.
QPSK vs OQPSK vs pi/4QPSK-Difference between QPSK,OQPSK and pi/4QPSK modulation techniques
Differential Encoder and Decoder

What is Difference between

difference between OFDM and OFDMA
Difference between SC-FDMA and OFDM
Difference between SISO and MIMO
Difference between TDD and FDD

RF and Wireless Terminologies