International Business Machines Corporation

Peter R Tomaszewski

Frank David Ferraiolo

Daniel Francis Casper

Robert S Capowski

Richard C Jordan

William C Laviola

Todd Morgan Rasmus

David Peter Pagnani

Beymer Bevill, Jr

James William Sylivant

William James Kalin

A telephone interface protection circuit and modem incorporating the telephone interface protection circuit. The circuit includes a sensing circuit and a determining circuit. The interface protection circuit checks for an active telephone line and checks the line for over-current conditions caused when a modem designed for the public switched telephone network is plugged into a private digital telephone network. The circuit functions when the modem is operating to provide continuous monitoring. It can be built as a stand-alone device or incorporated into a modem. The circuit notifies the user of the line condition either with LEDs or with a status message sent to the user via the host computer interface.

Telephone interface protection circuit and modem using same

An edge detector has a digital phase locking loop in which one of the signals (e.g., the data signal) is coupled to a delay chain that develops a series of incrementally phase delayed versions of the input. Adjacent phase delayed pairs are selected, one pair at a time, and are compared to the other signal (e.g., the clock signal) to determine if an edge of the clock falls between the edges of the data signal in the selected phase pair, or falls outside the edges of the selected phase pair, on one side or the other thereof. If the clock edge falls outside the selected pair, a control signal selects another pair for comparison and the process is repeated until, for example, the data edges are aligned with the positive going edge of the clock. With a clock frequency equal to twice data frequency, the data can then be sampled on the falling edge of the clock.

Edge detector

A compact, wide range inductor capable of being trimmed to a desired frequency value, comprising at least two individually tunable inductive elements of different resolution, disposed upon an insulative support. The inductor is usually placed within a hybrid circuit and trimmed after component population.

Tunable inductor

Growing community of inventors

Wake Forest, NC, United States of America

Peter R Tomaszewski