| 摘要 |
PROBLEM TO BE SOLVED: To reduce power consumption, and to improve reception sensitivity by making a loop band covered by a synthesizer part which outputs a local oscillation signal in a loop band wider than a band at the time of speech during the detection of an idle channel in a system band used in a radio system. SOLUTION: A synthesizer part constituted of a reference oscillator 1101, reference frequency-divider 1103, phase comparator 1105, and comparison frequency-divider 1111 or the like outputs a local oscillation signal in a loop band covering a system band used in a radio system to a receiving part. Also, the synthesizer part is provided with a loop filter 1 for a normal mode and a loop filter 2 for a high speed mode, and when a normal mode period is ended, it is switched to a high speed mode by a switch 1153, a frequency different from that of a speech channel is set, and an empty channel is searched. Then, a controlling means makes the loop band covered by the synthesizer part wider than a band at the time of speech during the detection of the empty channel in the system band. |
