| 摘要 |
A radio communication receiving device performs prescribed operations upon detecting a frequency modulation preamble signal consisting of a series of alternating logical values. The device includes a low-pass filter that is connected to an output of a receiver that detects the frequency modulation signal and outputs an analog base band signal, and which has a numerical cutoff frequency value that does not exceed half the bit rate of the preamble, a comparison circuit that is connected to the output of the low-pass filter and compares an output voltage of the low-pass filter with prescribed threshold values, and a determining circuit that determines a preamble has been detected when the comparison by the comparison circuit indicates that an absolute value the low-pass filter output voltage does not exceed a prescribed threshold value for a prescribed time period.
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