GFSK (Gaussian Filtered FSK)
GFSK is the variant of FSK in which the frequency transitions of the signal are smoothed by passing them through a Gaussian-shaped filter. The sideband energy produced by sharp transitions is suppressed, the spectrum occupied by the signal narrows, and the power spilling into the adjacent channel is reduced. It is widely used in remote control and telemetry modules.
In raw FSK the transition from one frequency to another is abrupt, so wide sidebands appear in the spectrum. This energy neither helps the receiver nor complies with band usage rules. The Gaussian filter spreads the transition along the time axis and suppresses those sidebands.
- Gain: a narrower spectrum, a measurable reduction in adjacent channel interference and easier compliance with spectral mask requirements.
- Price: symbols blend slightly into each other; if the filter bandwidth is narrowed too far, the error rate at the receiver rises.
- Application: in typical remote control and sensor modules it is an adjustable parameter; the transmitter and receiver must use the same setting.
The practical result is this: if more than one wireless set is to work on the same site, a narrow-spectrum link disturbs neighbouring channels less and is itself disturbed less. This makes a real difference in stability in multi-set operation.
Context where this term is used: Wireless remote control installation: pairing, relay, safety