| 摘要 |
PURPOSE:To maintain contineously an excellent reception state stably, by detecting a reception frequency for the best reception state while shifting the reception frequency slightly, in feedback-controlling a local oscillating frequency. CONSTITUTION:A noise detection circuit 9 detects noise level included in an output of a detection stage 5 and supplied the level to a controller 8 formed at a microprocessor. The controller 8 makes a variable frequency-division circuit 72 in a PLL circuit 7, varied controls the local oscillating frequency and supplies it to a mixing stage 3. Further, the controller 8 detects the reception frequency for the best reception state while shifting the reception frequency slightly based on the noise level signal. Thus, even if the interference of adjacent station exists near the desired reception frequency, this is avoided and the excellent reception state is continued stably. |
