Browse Prior Art Database

Adaptive Digital Equalizer for Communications Networks

IP.com Disclosure Number: IPCOM000117690D
Original Publication Date: 1996-May-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Coughlin Jr, TC: AUTHOR [+3]

Abstract

Disclosed is a description for a device that functions as a filter with adjustable attenuation characteristics. It is based on multiple delay segments which determine the slope and resolution of the filtering action. The output of each delay segment is gain weighted by a proceeding amplifier that is digitally controlled and externally written to provide the desired gain vs. frequency profile.

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Adaptive Digital Equalizer for Communications Networks

      Disclosed is a description for a device that functions as a
filter with adjustable attenuation characteristics.  It is based on
multiple delay segments which determine the slope and resolution of
the filtering action.  The output of each delay segment is gain
weighted by a proceeding amplifier that is digitally controlled and
externally written to provide the desired gain vs.  frequency
profile.

      This filter is basically of the Kalman family in that it
obtains the filtering action by summation of gain weighted time
delayed segments.  It differs from the typical Kalman implementation
in that it utilizes delay elements that can be fabricated on chip.
The length of these elements are of necessity very short, but the
quantity of them is very large.  The short length will physically
cause the filtering action to function best at high frequencies that
are usually typical of optical (fiber and air) communication systems.
The effective delay length can be altered by periodically inserting
gains of one in the delay chain.  The trade off is loss of resolution
in the frequency domain as compared to the effective bandpass of the
filter.  Assignment of the gains can be accomplished either by
directly writing the gain stages with a value determined a priori for
the application (which can be dynamically adjusted) or by adaptive
direction that drives to minimize a given measurable error signal.
Once configure...