Alan S Marshall

US Patent:

51329263, Jul 21, 1992

Filed:

Sep 21, 1990

Appl. No.:

7/586415

Inventors:

Stuart P. MacEachern - Uxbridge MA
Alan C. Marshall - Framingham MA
Howard C. Salwen - Newtonville MA

Assignee:

Proteon, Inc. - Westboro MA

International Classification:

G06G 702
H03H 730
H04L 700
H03D 324

US Classification:

364825

Abstract:

An improved local area network ring node of the type described in ANSI/IEEE Standard 802. 5, including a receiver having an input connectable to the ring, a phase-locked loop circuit for extracting a clock frequency from the receiver output and including a phase detector for generating a phase error signal, and a data demodulator connected for demodulating at the extracted clock frequency the data in the receiver output. The improvement lies in the provision of a filter for deriving a control signal from the outputs of the data demodulator and the phase detector and an adaptive equalizer for reducing the effect of jitter in signals applied to the receiver input from the network, the equalizer comprising a filter network including a voltage variable impedance so connected as to vary responsively to the control signal.