| 摘要 |
PROBLEM TO BE SOLVED: To provide a device for preventing the arrival of an incoming call to a portable phone of a mobile phone system adopting a cellular system that covers a wide frequency range and can set an area proving the suppression effect onto the arrival of incoming calls with high accuracy. SOLUTION: This device roughly consists of a PLL system circuit section (block 1) and an open loop system circuit section (block 2). The block 1 consists of crystal oscillators 3, 6, 17 that generate a reference signal, a frequency divider circuit/phase comparator circuit 5, a loop filter 8, a signal adder 10 that adds an output signal from the loop filter 8 to a frequency modulation signal 29 described below, a VCO 12, and an RF power amplifier 23 or the like. The block 2 consists of a D/A converter type frequency sweeping circuit 31, a VCO 33, and an RF power amplifier 35 or the like. A control microcomputer 2, a control program 4 and a power supply section 48 or the like are used in common for both the blocks. A desired frequency is oscillated through the selection of a frequency selection signal 14, a frequency sweep circuit control signal 43 and an analog frequency sweep circuit 44, a required frequency band is obtained and amplified by a required modulation means and a radio wave is emitted to suppress the arrival of incoming calls.
|
