| 摘要 |
PROBLEM TO BE SOLVED: To not only reduce the power consumption on the slave unit side but also avoid a condition that communication is impossible due to interference waves, in intermittent radio communication. SOLUTION: In an intermittent radio communication system where narrow-band radio channels are shared between a master unit and a slave unit to perform communication, reception signals in the entire band of available channels are subjected to fast Fourier transform to calculate the signal intensity or the like of each channel, and the possibility of being a desired signal is evaluated. Data demodulation is performed in an ordinary narrow band receiver with respect to channels determined to have the possibility. Radio packet data sent from the slave unit to the master unit consists of a preamble for wide band reception, a preamble for narrow band changeover guard, a synchronizing word for narrow band reception, and a data part. The preamble for wide band reception allows a wide band reception part to recognize the existence of a packet by the signal intensity. The preamble for narrow band changeover guard corresponds to a time required for changeover from wide band reception to narrow band reception in the master unit. COPYRIGHT: (C)2004,JPO&NCIPI
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