| 摘要 |
A dynamic threshold data receiver uses a single comparator for both squelch and data detection. The comparator has a high-magnitude threshold when the receiver is squelched and a low-magnitude threshold when the receiver is unsquelched. A squelch signal is provided by squelch control logic responsive to a comparison signal from the comparator. The squelch control logic has an interval timer comparing intervals of the comparison signal to a predetermined duration of time, and the squelch control logic changes the squelch signal from the asserted state to the unasserted state after the interval timer determines that the magnitude of the signal level on the comparator input has exceeded the high-magnitude threshold for at least said predetermined period of time. Preferably the squelch signal is not asserted until two transitions occur in the comparison signal after the high-magnitude threshold has been exceeded for the predetermined period of time, and the squelch signal is reasserted when a transition fails to occur in the comparison signal for a predetermined duration of time. Preferably the comparator is a differential line receiver, and each of the high and low magnitude thresholds has hysteresis.
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