| 摘要 |
PURPOSE:To stabilize a transmission frequency by providing an oscillator generating the reference frequency of a transmission wave in response to a control voltage and a means measuring the frequency of a received wave, calculating the reference frequency of the oscillator from the frequency of the reception wave at a CPU to apply the control voltage in response to the reference frequency to the oscillator. CONSTITUTION:An oscillator 3 generating the reference frequency of a transmission wave in response to a control voltage and means 1, 2 measuring the frequency of a received are provided, a CPU 5 calculates the reference frequency of the oscillator depending on the frequency of the reception wave and applies the control voltage in response to the reference frequency to the oscillator 3. That is, the CPU 5 has a memory having an area to store the counted value of the counters 1, 2 and other work area, a D/A converter 6 converts a voltage controlled by the CPU 5 into an analog value and applies the result to a temperature controlled crystal oscillator 3. Thus, since the CPU 5 controls the control voltage of the oscillator, the transmission frequency is controlled in real time. Thus, the transmission frequency is stabilized in an optimum condition. |
