| 摘要 |
PURPOSE:To prevent the mis-channel selection, by stopping AFC until the preset voltage is sufficiently stable. CONSTITUTION:In the preset tuning, the up and down counter 10 counts until the count value stored in the memory 11 and the multi-bit digital signal is in D/A conversion to obtain the tuning voltage. Further, the window comparator 13 detects the tuning shift with the demodulation output so that the up down counter 10 is moved to + or - according to the shift. The control circuit 16 outputs inhibit signal to the inverter 21 while the preset voltage is sufficiently stable at the preset tuning to stop the opration of the correction circuit of tuning shift. Accordingly, when the preset voltage is unstable, no frequency is drawn in the other stations received. |
