| 摘要 |
PURPOSE: A frequency transfer keying type radio communication modem having a PLL(Phase Locked Loop) is provided to improve quality of communication by using a crystal oscillator as an oscillator of a phase loop method. CONSTITUTION: An RF modem type transmission part has a PLL circuit including a phase detector, a loop filter, and a voltage controlled oscillator. The PLL circuit of the RF modem type transmission part is used as an oscillator for generating a frequency. A super heterodyne type reception portion has a PLL circuit including a phase detector, a loop filter, and a voltage controlled oscillator. The PLL circuit of the super heterodyne type reception portion is used as a local oscillator. The RF modem type transmission part further comprises a phase asynchronous detector, a micro computer, and a transmission output breaking circuit. The super heterodyne type reception portion further comprises a detector and a data slicer.
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