| 摘要 |
A system for selecting a signal having a median frequency from a plurality of periodic signals of different frequencies. In one embodiment, three such periodic signals are converted into corresponding pulse sequences, each having a duty cycle of approximately unity and a frequency which corresponds to the frequency of its associated periodic signal. An output signal is generated which assumes a first logic state when a positive signal slope of a first pulse sequence, which places the first pulse sequence in a first logic state and occurs while the output signal is in a second logic state, is followed by a further positive signal slope of a second pulse sequence, while the first pulse sequence is in its first logic state. The output signal assumes a second logic state when successively negative pulse sequence slopes occur. |
