Automatic frequency correcting circuit

Abstract

Abstract PURPOSE:To obtain a satisfactory receiving condition with all tuning frequencies by correcting the local oscillation frequency of an electronic tuner by an AFC voltage obtained when a regular tuning frequency is set while an irregular tuning frequency is set. CONSTITUTION:When an electronic tuner 4' is tuned at an irregular tuning frequency, a microcomputer 2 reads a tuning voltage V1 of the irregular tuning frequency stored in the first special area of a memory element 1' for a constant period, outputs it from a terminal 1 and sets the electronic tuner 4' to the regular tuning frequency. Simultaneously, a microcomputer 2' reads the control voltage of H from the memory element 1', outputs it from the terminal 3 and makes a transistor 6 into an ON condition. Thus, the local oscillation frequency is corrected by the AFC voltage from an AFC voltage generating circuit 5 at the electronic tuner 4'. For this reason, without being influenced by the ambient temperature and the change with the passage of time, the irregular tuning frequency is correctly set.

Inventors

• 👤 Makoto Ishii
• 👤 誠 石井

Bibliographic Details