| 摘要 |
PROBLEM TO BE SOLVED: To easily, quickly and accurately search for an antenna direction in which a receiving field intensity is maximum. SOLUTION: An antenna 12 turns off a switch 32 when taking a specified direction. In this time a PLL 20 is disabled to fix the frequency of sound signals outputted from a VCO 24 to that of sound signals outputted from a VCO 22 when the antenna 12 takes the specified antenna direction. When the antenna 12 changes its direction from the specified direction, the frequencies of the sound signals outputted from the VCOs 22, 24 become different to produce a beat sound. An operator determines a middle direction between the specified direction and a direction in which approximately no beat sound is produced, thereby adjusting the direction of the antenna 12. COPYRIGHT: (C)2004,JPO
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