| 摘要 |
PURPOSE:To obtain an inexpensive constitution by using a micro-computer as a substitute for a programmable counter. CONSTITUTION:The oscillation frequency of voltage control oscillator 5 is phase- compared 6 with a frequency integer times-as high as fixed frequency (fa), and the phase error signal is passed through LPF7 and controls the frequency of oscillator 5. The oscillation output of voltage control oscillator 5, on the other hand, is counted 8 and the output of it is compared 9 with the discrete value assigned to input circuit 10. Comparator 9 and input circuit 10 are both incorporated in microcomputer Q. Then, D/A converter 11 comverts a pulse signal from comparator 9 into a direct current proportional to its pulse width. The microcomputer like this is used to realize a frequency synthesizer, thereby attaining accurate reception. |
