AUTOMATIC FREQUENCY SWEEPING METHOD FOR CONTROLLING A FREQUENCY SYNTHESIZING TYPE AUTOTUNER

摘要

An automatic frequency sweeping method for controlling a frequency synthesizing type autotuners for broadcasting receivers comprises a first intermediate frequency counting method in which the intermediate frequency is counted for a relatively short first time and the presence or absence of the received signal is judged in a first range having a relatively wide intermediate frequency width and a second intermediate frequency counting method in which the intermediate frequency is counted for a second time longer than the first time and the presence or absence of the received signal is judged in a second range having an intermediate frequency width narrower than that of the first range. Thus, a high speed frequency sweeping is ordinarily executed by using the first intermediate frequency counting method, and when the presence of the received signal is judged in the first intermediate frequency counting method, a more precise judgment is made in accordance with the second intermediate frequency counting method.