Communications engineering. A modulation technique that modulates the user data on to a carrier frequency which jumps in a pseudo-random way from one frequency to another. The jumping order has to be known to transmitter and receiver to make a demodulation in the receiver possible. FHSS works in the ISM-band (2.4 - 2.4835 GHz) with a maximum transmission power (in Germany) of 100 mW EIRP and a maximum data rate of 1 MBit/s. It is defined in IEEE 802.11. Due to the constantly changing frequency during transmission eavesdropping is difficult and the interference with other devices or through multipath-transmission is rather small. FHSS is used in mobile communications and WLANs.