| 摘要 |
PURPOSE:To reduce the required time of AFT operation and to minimize the oscillation of superimposed operation, by greatly changing the initial data and performing minute adjustment through the correction of superimposed amount when the AFT signal is inverted. CONSTITUTION:When a start pulse is input, FF22 is set and the counter circuit is reset to obtain 111. The subtraction circuit 31 substracts the data A from the register circuit 34 from the data 7 from the circuit 25, and A-7 is written in the circuit 34. Thus, the superimposed value is gradually moved to the level of A-7. On the way of change of superimposed value, when the tuning frequency crosses the broadcast frequency, the circuit 31 is switched to the addition mode and the operation pulse alpha is fed to the circuit 31. In this case, the circuit 25 is at 011, the value 3 is written in the circuit 34, and the value of the circuit 34 is A-4. Next, FF22 is reset, the operation of the circuit 25 is stopped and the superimposed value is changed to the level of A-4. Next, fine adjustment clock pulse is input to the circuit 34 and the data in the circuit 34 is slowly changed. |
