| 摘要 |
PURPOSE:To attain highly accurate and stable frequency control by measuring the output frequency of a frequency demodulating oscillator, comparing the frequency with a reference value and controlling the variable frequency division ratio of a frequency converting local oscillator section based on the error voltage. CONSTITUTION:The output frequency of a voltage controlled oscillating means 10 is measured by using a frequency measuring means for automatic frequency control in a receiver using PLL synthesizers 3-6 as a local oscillator and using a voltage controlled oscillating means 10 as a frequency demodulating means 10, and the result is inputted to a microprocessor 13. The processor 13 compares the measured data with a predetermined frequency reference data and outputs an error signal. The error signal is fed to a variable frequency division means 4 of a PLL synthesizer to control the frequency dividing ratio. Even when the intermediate frequency is fluctuated by the fluctuation of a reception frequency or a local oscillating frequency, the oscillated frequency of the local oscillating means 3 is changed automatically for the share. |
