FREQUENCY HOPPING RADIOCOMMUNICATION SYSTEM AND SYNCHRONOUS CATCHING METHOD

摘要

A frequency hopping radiocommunication system for transmitting and receiving signals while periodically hopping a carrier wave frequency in accordance with a predetermined hopping sequence, comprises a frequency synthesizer (50) for switching the frequency of the output signal, a detection circuit (32) for detecting a reception signal at the output signal frequency from the frequency synthesizer, a demodulation circuit (35) for demodulating the reception signal from the output of the detection circuit, and a hopping controller (55) for controlling the synthesizer. The hopping controller has a low speed hopping mode (102 to 106) for instructing the frequency synthesizer to switch the frequency for a predetermined cycle in accordance with a hopping frequency sequence which defines a hop sequence for different frequencies, and a high speed hopping mode (121 to 135) for instructing the frequency synthesizer to switch the frequency at a switching rate substantially corresponding to one cycle of the sense frequency sequence during the duration for which each carrier wave frequency continues in accordance with a sense frequency sequence which defines a hop sequence of a limited number of frequencies existing in discrete hop positions in the hopping frequency sequence. When the carrier is detected from the detection circuit output while the frequency synthesizer outputs a specific frequency in the high speed hopping mode, the operation mode is switched to the low speed hopping mode, using the hop position corresponding to a specific frequency in the hopping frequency sequence as the starting point.