FHSS - Frequency Hopping Spread Spectrum
Frequency Hopping Spread Spectrum (FHSS) is a spread spectrum technique used in radio transmission systems. In a FHSS systems the data is sent using a transmission frequency that moves from one frequency to another in a "hop" sequence. Hence, a hopping pattern can be observed in the spectrum.
FHSS is for instance used by Bluetooth. Bluetooth hoppes 1600 times per second between the 79 available channels.
See further spread spectrum