Frequency-hopping spread spectrum

A radio transmission method that changes carrier frequency according to a shared pseudorandom sequence. The rapid hops spread transmission energy across a wider band and can resist interference and interception.

Frequency-hopping sequence: A predetermined sequence of radio frequencies that a transmitter and receiver use for successive hops. It determines the channel order shared by the transmitting and receiving radios.
Carrier wave: A periodic electromagnetic wave whose frequency, phase, or amplitude can be varied to carry information. Hopping changes this wave's frequency while carrying the underlying message.
Bluetooth: A short-range wireless technology for exchanging data between devices in the 2.4 GHz band. Classic Bluetooth uses adaptive frequency hopping to avoid persistently busy channels.
Hedy Lamarr: An Austrian-born American actor and inventor who co-patented a frequency-hopping radio control system with George Antheil. Her 1942 patent proposed synchronized hopping to make torpedo guidance harder to jam.
Orthogonal frequency-division multiplexing: A multicarrier modulation method that transmits data simultaneously on many orthogonal subcarriers. It uses many frequencies at once rather than switching a narrowband signal among channels.
Frequency-hopping synchronization: The process of aligning transmitter and receiver timing and frequency-sequence position. Both radios must hop together to keep the receiver on the transmitted signal.
Radio frequency: The range of electromagnetic frequencies used for radio communication and related applications. The method selects successive channels from this broader part of the spectrum.
GSM: A second-generation cellular standard that digitizes voice and data over time- and frequency-divided channels. GSM networks can assign mobile transmissions to hop among radio frequencies.
George Antheil: An American avant-garde composer and inventor who co-patented a frequency-hopping radio control system with Hedy Lamarr. His player-piano expertise inspired the patent's synchronized control of changing frequencies.
Channel hopping: A wireless communication technique that changes operating channels over time, often to improve coexistence or avoid interference. It describes a broader practice that may hop channels without spread-spectrum signaling.

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