In this type of spread spectrum approach, both units (base and subscriber or handset and base) hop from frequency to frequency in a simultaneous fashion. The theory is that noise tends to occur at different frequencies at different times. Therefore, even though a part of a transmission may be lost due to interference, enough of the message will come through by hopping the interference to create a noticeably better output when compared to fixed frequency systems.
Bluetooth's way of creating less interference between two devices. By quickly jumping frequencies, there is a very minute chance of devices interfering by connecting on the same frequency. There are five different types for the 79MHz range, and five different types for the 23MHz range (mainly used in Spain and France).
Frequency hopping is one of two basic modulation techniques used in spread spectrum signal transmission. It is the repeated switching of frequencies during radio transmission, often to minimize the effectiveness of "electronic warfare" - that is, the unauthorized interception or jamming of telecommunications. It also is known as frequency- hopping code division multiple access (FH-CDMA).