| 摘要 |
PURPOSE:To offset the temperature change and the secular change by providing the difference circuit with the frequency discriminating circuits formed in the same constitution, and thus to ensure the steady AFC action as well as to realize easy integration. CONSTITUTION:Output signal fQ1 and fQ2 of 1st and 2nd D-type FF5 and 6 are supplied to 1st and 2nd monostable multivibrator 7 and 8 to produce the output which becomes ''1'' in a fixed time tau from the rise or fall of signal fQ1 and fQ2 and becomes ''0'' at other time. The output is applied to 1st and 2nd integrating circuit 9 and 10 to be integrated. After this, the difference is secured through difference circuit 11 between two DC components in order to obtain the DC signal which is proportional to deviation amount + or - fM to central value fM of the frequency of frequency discriminated signal SM, i.e., the data terminal input frequency of FF5 and 6. This DC signal can be used as the AFC signal. And the frequency discriminating circuits of pulse counting system, which are formed with multivibrator 7 and 8 plus circuit 9 and 10, are obtained in the same constitution. |
