| 摘要 |
A signal processing circuit with a comparator having a fixed and a variable reference input is provided for detection of a positive quasi-sinusoidal waveform pulse. The signal detection circuit includes a low pass input filter, a voltage input clamp, a variable detection threshold, and a zero crossing detector. The circuit produces an approximately square wave output substantially coinciding with the positive pulse of the quasi-sinusoidal waveform received, for example, from a variable reluctance sensor. The circuit may be used as a positive to negative zero crossing detector having detection armed by a variable threshold of the positive quasi-sinusoidal pulse, thus providing variable noise immunity and a fixed phase relationship between the input and output signal for an input signal having a variable amplitude.
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