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Intelligent Receiver with Multiple Hysteresis Levels

IP.com Disclosure Number: IPCOM000114114D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Gill, DE: AUTHOR [+3]

Abstract

Described is a receiver that automatically selects the correct hysteresis level based on an algorithm that is applied to the received waveform. This design resulted from a requirement for a communication media receiver to operate properly on an electrically noisy media, over a short distance such as a TTP application; and on a quiet media, but over a long distance such as a coax application. The short distance, noisy application requires a large receiver hysteresis to reject noise; while the long distance, noise-free application requires a small receiver hysteresis to properly receive the attenuated signal.

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Intelligent Receiver with Multiple Hysteresis Levels

      Described is a receiver that automatically selects the correct
hysteresis level based on an algorithm that is applied to the
received waveform.  This design resulted from a requirement for a
communication media receiver to operate properly on an electrically
noisy media, over a short distance such as a TTP application; and on
a quiet media, but over a long distance such as a coax application.
The short distance, noisy application requires a large receiver
hysteresis to reject noise; while the long distance, noise-free
application requires a small receiver hysteresis to properly receive
the attenuated signal.

      An implementation of a dual threshold receiver is shown in the
Figure.  The differential input signal from the media appears between
POS and NEG.  The receiver output is the waveform at DATA.  The input
signal is applied to three analog comparators (CMPL, CMPH, and
CMPDH), each with a different hysteresis level.  The input signal at
CMPL is first passed through an EQUALIZER to improve the quality of
the waveform.  The CMPL has the smallest hysteresis, and is used for
communicating over long distance media.  The CMPH has a higher
hysteresis, and provides a higher immunity to noise switching the
receiver when no signal is present.  The CMPDH has the largest
hysteresis.

      The digital outputs of CMPL (LOW) and CMPDH (DHIGH) are
analyzed by the DIGITAL ALGORITHM CIRCUIT which applies a...