| 摘要 |
PURPOSE:To make it possible to correct a frequency with high precision by use of a single oscillator by calculating a fluctuating frequency from a difference in temperature and coefficient by use of a quartz oscillator with temperature frequency characteristics represented by a curve of degree (n) and then by adding or subtracting a pulse to and from a fixed frequency-dividing stage for the correction. CONSTITUTION:On the basis of the characteristic measured value of an AT cut quartz oscillator, measuring instrument 1 determines each coefficient ai and then stores it in memory unit 2. On receiving a periodic timer output from terminal (c) of control circuit 4, temperature measuring instrument 3 measures temperature difference DELTAT between a set temperature and a temperature in a correction. On the basis of temperature difference DELTAT in unit 3 and coefficient ai stored in unit 2, arithmetic circuit 5 performs fixed arithmetic for obtaining fluctuations of the frequency and sends a code output for the determination between addition and subtraction of a correction pulse to terminal (a) and the absolute value of variation DELTAf to terminal (b) respectively. This b-terminal output is written into preset down counter 6 and through the operation of control circuit 4, pulse adding-subtracting operation is performed by use of the a-terminal output and the variation output of counter 6, thereby supplying clocking unit 22 with a corrected time display input by way of frequency-dividing stage 21. |
