| 摘要 |
A digital detector for a 5 Hz signal is combined with a detector for Manchester encoded data with a frequency of 2.5 Hz. The preferred apparatus includes a signal generating means in the form of an oscillator which generates a signal of a known frequency higher than that of the 5 Hz signal. This oscillator is connected to a frequency responsive means and to the circuit in which 2.5 Hz and 5 Hz signals are to be detected. The frequency responsive means produces an output signal in response to the generation of a given number of cycles of said higher frequency signal during one half of any cycle of said predetermined low frequency signals. Also connected to the frequency responsive means and to the circuit in which the predetermined low frequency signals are to be detected is a detection signal means. This produces a detection signal in response to the reception of an output signal from the frequency responsive means and a signal indicating the end of a half cycle of either the 2.5 Hz or 5 Hz signal.
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