Siemens Corporate Research & Support, Inc.

Siemens Aktiengesellschaft

Siemens Corporation

Gary D Southard

The invention relates to a transmission testing arrangement for executing performance tests for a telecommunication system which includes a central switch to the common control unit, a switching network, and line interface units internally connected to the switching network and adapted for connection to a corresponding line circuit. The testing arrangement includes a bus-oriented microprocessor system for synthesizing and analyzing test signals, a program memory, a main memory, and first and second interface modules.

Programmable testing analyzer

A clock pulse generator system for providing a highly stable clock signal consists of two separate redundant clock signal generators which are controlled to operate in dead synchronization with each other. A microprocessor controlled digital phase lock loop operates to control each of the two clock signal generators and selects among a plurality of operating states such that the average dynamic phase difference in the two clock pulse signals generated is practically zero. Furthermore, the instantaneous dynamic phase difference does not exceed the phase noise of the voltage controlled crystal oscillators of the phase lock loops and, in one embodiment, is normally less than ten pico seconds, each phase lock loop comprising means for performing a fine, as well as coarse, phase comparison among internally or externally generated reference signals, only one of which is the highly stable clock signal output.

Clock pulse signal generator system

Apparatus for producing a time standard including a source of radiation, two fibers of different length to transmit the radiation, and means to produce a signal representative of the difference in propagation time through the fibers that is constant despite temperature changes.

Fiber optic time standard

An electronic system, such as a telephone exchange, including at least two, redundant computers. One computer is operated in the active mode while one or more are maintained in a hot 'standby mode' in readiness to take over the tasks of the active computer if this computer should fail. At least one 'cross channel circuit' is provided for updating the memory of the standby computer(s) in accordance with changes made in the contents of the memory of the active computer. The cross channel circuit changes the contents of the memory of the standby computer only at addresses which are within a prescribed, contiguous range of addresses.

Cross channel circuit for an electronic system having two or more

A digital telecommunications system having an adjustable attenuation member incorporates first and second memories for altering the values of different pulse code modulated words, representing different amplitude values of transmitted waves, such as tone frequencies. One of the memories alters the first three amplitude bit values of a special pulse code modulated word to alter the values for example in six-dB steps. The other memory defines the values of smaller steps. The change of the output code from the first memory and the determination of the characteristic to be output by the second memory is dependent upon control signals from a control unit.

Adjustable attenuation member for a digital telecommunications system

A digital tone generator for use with a digital telecommunication system for simultaneous generation of continuous and cyclically repeated discontinuous tone signals each composed of at least one frequency component incorporates sequencing control means, amplitude control means, amplitude value generating means and output means. The sequencing control means generates consecutively incremented reference address signals directing the course of an operating cycle, thus allowing for some amount of parallel processing of the sub-units. The amplitude control means produce amplitude control signals which determine varying mean amplitude values of a discontinuous digital tone signal at the commencement of the rising and trailing ends of each pulse. Any stepwise adjustment of the mean amplitude value takes place coincidentally with an instantaneous amplitude of zero value and in accordance with a predetermined attenuation curve. The amplitude value generating means connected to receive the reference address signals and the amplitude control signals furnish a digital encoded signal representing an instantaneous amplitude value of a respective digital signal to output means for transmitting the same onto a time multiplexed transmission line.

Digital tone generator

In a PCM time multiplex switching system total code words are formed from individual PCM words supplied by the conference parties. In the process, intermediately constructed sum code words are stored, up-dated and restored upon the arrival of a new individual PCM word. Each arriving PCM word is also delayed by one pulse frame and subtracted from an intermediate code word to form the total code word which is transmitted to that party from which the delayed code word originates. The intermediate code words are stored in a connection memory which has two sections which receive alternate individual code words and which alternately connect the intermediate code words to an input adder and to an output subtracter for up-dating at the input and code word removal at the output.

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Coral Springs, FL, United States of America

Gary D Southard