| 摘要 |
PURPOSE:To move a frequency to the adjacent broadcasting frequency by automatic tuning, by stopping to count only when a memory circuit is clear-state and a stop signal comes in the automatic tuning unit of a synthesizer tuner. CONSTITUTION:Broadcasting signal radio waves are demodulated to audio signals by antenna ANT, high-frequency amplifier part RF, mixer MIX, intermediate- frequency amplifier part IF and detector part DET. Phase synchronizing loop PLL is constituted by reference oscillator OSC1, programmable frequency divider PD, phase comparator phi/D, low-pass filter LPF and voltage control oscillator VCO; and an automatic tuning unit is constituted by CR oscillator OSC2, gate circit G1, memory circuit MEMO, control part CONT, AND circuit A1, start switch SW and up/down-counter U/D-C. |
