Xel Communications, Inc.

John A Neely

Terry D Bolinger

Ninh T Nguyen

Kevin S Machemer

A data link access unit for insertion into a T1 span supporting the extended superframe (ESF) format includes an interface for accessing the frames of digital data carried by the T1 span in ESF format (including the data link bits) and calculating performance monitoring data for the T1 span. The interface is controlled by a processor that can access this performance monitoring data and also communicate message data over the data link channel via the interface. Additionally, the unit can provide an ESF/SF interface when inserted into a T1 span between a first channel bank supporting ESF and a second channel bank that does not support ESF.

Data link access unit for T1 spans supporting the extended superframe

The universal channel unit includes a channel interface circuit that uses a pair of fixed ratio transformers to terminate both two wire and four wire analog transmission facilities on a selectable basis. The universal channel unit also includes a plurality of signalling circuits, each of which is switchably connectable via the channel interface unit to provide a DC signalling interface to match the signalling format required by the associated analog transmission facility. The signalling circuits include: DX, FXO, FXS, and other DC signalling circuits. The AC component of the signals carried by the analog transmission facility is output to an adaptive impedance and balance circuit which functions to closely match the impedance of the analog transmission facility and minimize signal reflections under control of a microprocessor. This impedance and balance network is connected to a PCM interface that includes an adaptive echo canceller circuit as well as equalization and gain control circuits.

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Aurora, CO, United States of America

John A Neely