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Frequency shift keying (FSK) demodulator for use in low signal-to- noise ratio environments
Frequency shift keying (FSK) demodulator for use in low signal-to- noise ratio environments
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机译:频移键控(FSK)解调器,用于低信噪比环境
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摘要
A frequency-shift keying (FSK) demodulator demodulates a binary signal encoded in an FSK signal. The present invention employs a bandpass filter to filter out noise and pass the frequencies used in the modulation. A comparitor converts the received signal into a square wave. A divider reduces the frequency of the square wave signal by a dividing factor. A counter counts the number of square wave transitions in a predetermined time period. A decision device receives the dividing factor from the divider, and uses this factor to adjust the count measured. The adjusted count is compared to counts pertaining to modulated frequencies to select a frequency. A bit value associated with the selected frequency is output for the time period being demodulated.
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