International Business Machines Corporation

Jean-Louis H Marijon

Pierre Debord

Christian A Jacquart

Michel Paul Verhaeghe

Gerard Orengo

Jacques A Besseyre

Jean-Claude Froment

A digital signal distribution system for distributing digital signals to remote points of a machine. It is comprised of a distribution device arranged at each of said points. In each device, a receiver receives on its true and complementary inputs, the signal to be distributed. The drivers are connected to the receivers through a crossed connection, the true output of the receiver being connected to the complementary input of the driver, and the complementary output of the receiver being connected to the true input of the driver, so as to cancel the skew of the pulse width of the signal to be distributed. The signals on outputs of the driver circuits can be utilized locally or transmitted to another remote point.

Digital signal distribution system

Disclosed is a dynamic compensation circuit for correcting the residual offset voltage encountered in an analog-to-digital conversion chain. Samples of an analog signal having an average value equal to 0 are provided to a first input of a comparator, the second input of which receives a reference signal generated through a D to A converter under control of a control logic circuit. A sample and hold circuit with the comparator causes a DC offset of the output signal level which is to be dynamically corrected by the compensating circuit of the invention. The DC offset causes the duty cycle to differ from one by an amount .DELTA.DC which will be the error curve signal of the compensation circuit. The compensating circuit reduces the .DELTA.DC to 0 by adding to the signal a DC voltage opposite to and of equal magnitude to the offset voltage level.

Dynamic zero offset compensating circuit for A/D converter

An acoustic feedback control to be installed in every extension provided with a loud speaker and a microphone in a digital telephone system. Each extension is provided with a coder and a decoder of the syllabic compression type which therefore have quantizing steps varying with the voice level at the input of the transmission channels between two extensions. A comparator receives the step information from the coder and decoder and prevents the decoder step from increasing when the coder step exceeds the decoder step.

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Saint Laurent du Var, France

Jean-Louis H Marijon