| 摘要 |
PURPOSE:To make AFT superposing possible in a prescribes step in either of low and high channels, by forming fine tuning data by an AFT signal generating circuit and by setting it to a programmable frequency divider. CONSTITUTION:Frequency division ratio setting data for setting a prescribe channel is set to U/D counters 32-36, and fine tuning data corresponding to the shift of the intermediate frequency outputted from an electronic tuning tuner 21 is formed by an AFT signal generating circuit 37 and is applied to U/D counters 32-36 and is added to or substracted from frequency devision ratio setting data, and the operation result is read out by transfer gates 38-42 and is transferred, and this transferred data is supplied to a designated input terminal of a programmable frequency divider 23 through data latch circuits 46@49, and passage of the receiving center frequency is detected by the AFT signal generating circuit 37 and a clock pulse forming circuit 44, and the frequency division ratio of the programmable frequency divider 23 is varied each time it is detected. |
