A spread-spectrum transmission technology for wireless networking. Spread-spectrum wireless technologies trade throughput for increased reliability, and were originally developed by the U.S. military to provide communication that could not easily be jammed.
Frequency hopping transmitters take the incoming data stream and segment it into multibit packets. These packets are then transmitted sequentially in a pseudo-random manner over the various frequency channels within the spread-spectrum band being used. In other words, the frequency of the carrier signal keeps hopping around. Synchronization between the master transmitter and slave devices is achieved by modulating the center or carrier frequency of the communication band according to a preset algorithm. Both the mobile and the base station know the modulation algorithm, which enables them to keep in communication with each other. For increased security, the modulation algorithm can be dynamically modified.
Graphic F-22. Frequency hopping.