Societe Anonyme De Telecommunications

Etat Francais

Etat Francais (Ministry of Posts and Telecommunications -- Centre

Patrick E Boutmy

Jean G Walraet

Gilbert J Le Fort

Marc Liger

Yvon N Madec

Jean-Marc A Camborde

Gilbert LeFort

Michel Stutzmann

Frederic M Platet

Marcel R Bertin

A predetermined characteristic of each of incoming plesiochronous component signals in a time-division multiplexing equipment is derived at each stuffing time for transmission in the form of a stuffing bit in a respective stuffed signal to be multiplexed in a resulting signal. In a demultiplexing equipment receiving the resulting signal, the stuffing bit in a respective demultiplexed stuffed signal is sampled and simultaneously the predetermined characteristic of the plesiochronous signal outgoing from the demultiplexing equipment is derived at each unstuffing time. The sampled stuffing bit and the derived predetermined characteristic are compared in order to measure the transmission quality of a digital channel carrying the component signal through the two equipments. The predetermined characteristic is preferably the parity of the signal between two consecutive stuffing and unstuffing times. The results of the comparisons, in the form of error signals relating to the component signals, contribute to locating faults in the two equipments, signalled by a checking unit included in the demultiplexing equipment.

Multiplexing and demultiplexing method and equipments measuring

A subscriber television set terminal is linked to a distribution station receiving M television channels in a videocommunication network. The distribution station comprises as many individual channel selectors as there are television channels. A television channel is selected from a terminal by a digital video switching matrix that, for each channel address transmitted in a backward line of a terminal connecting line, connects the addressed channel selector to a forward line in the connecting line.

Television channel distribution network

This invention relates to an arrangement for transmitting a digital supplementary information signal having a low rate with a digital data signal having a high rate. The insertion of the supplementary information in the data signal is based on the modification of the accumulative disparity of data signal as a function of the logic level of the supplementary information signal. According to a first embodiment, parity check words are periodically inserted in the data signal and have their accumulative disparity which depends upon the comparison of the desired parity indicated by the logic level of the supplementary information signal with the accumulative disparity of data digits between two successive parity check words. According to a second embodiment, the parity check words are words which correspond to the binary-to-ternary transcoding of a predetermined bit group of the data signal which is scrambled into a pseudo-randomized signal having a constant accumulative disparity over a predetermined period of time.

Supplementary information transmitting arrangement for a digital data

Monitoring system for a forward and backward link equipped with two way repeaters-regenerators comprises a monitoring station including means for transmitting through the forward link information data and a low frequency control signal and for receiving through said backward link information data and supervisory words respectively monitoring the performance of the repeaters-regenerators and identifying errors made therein. In each repeater regenerator a supervisory word is stored in a shift register and advance pulses for said shift register are obtained by frequency division of the low frequency control signal. The supervisory word is completed by a start bit and a stop bit, and modulates the low frequency control signal. The modulated start stop supervisory word is transmitted to the monitoring station through the backward link.

Monitoring system for telecommunication links equipped with

A digital multiplexing and demultiplexing system for time division multiplexing a number of incoming plesiosynchronous low rate component signals and a number of incoming plesiosynchronous intermediate rate component signals into an outgoing single high rate signal. A first multiplexing stage time stores and stuffs the low rate component signals and multiplexes them into synchronous intermediate rate signals. A second multiplexing stage stores and stuffs the plesiosynchronous and synchronous intermediate rate signals and multiplexes them into the outgoing high rate signal.

Digital multiplexing and demultiplexing system

A remote locating system for remote locating the pairs of regenerative repeaters of a bidirectional data transmission line which is interconnected between a monotoring station and a monitored station. The monitoring station comprises a first low frequency generator which generates a first low frequency signal on the forward line channel which is continuously transmitted in the forward direction from the monitoring station to the monotored station in response to the fault detection on the line and a second low frequency generator which generates a second low frequency signal on the backward line channel which is transmitted in the forward direction after the transmission beginning of the first signal. The second signal is modulated by successive pulses, each of which identifies a regenerative repeater pair. The first signal is simultaneously detected in each forward transmission regenerative repeater and controls the connection of the output and the input of the forward and backward transmission regenerative repeaters of each pair. In the backward transmission regenerative repeater of each pair the pulse which identifies the next pair, is detected for connecting the input and the output of the backward regenerative repeaters of the pair and the next pair and for disconnecting the regenerative repeaters of the pair. The first and second low frequency signals are mixed with a digital testing signal which is transmitted from the monitoring station through the connected pair and is monitored between two successive pulses so as to detect the transmission faults of the connected pair or the connected line section.

Remote locating system for transmission faults in data transmission line

In a time-division digital transmission system comprising transmitting and receiving stations interconnected by transmission lines, a number of component digital channels having a low flow rate are multiplexed into a single resultant channel having a high flow rate. The code used in the stations is a binary code and the code used in the lines is a multi-level code such that a number N of bits in the binary code corresponds to a smaller number N' of digits of the multi-level code. Consequently, a predetermined flow rate in the stations corresponds to a smaller flow rate in the lines, equal to N'/N times the flow rate in the stations. The system comprises, in the transmitting part of a station, means for placing in parallel the bits of a number of component channels equal to a multiple k of N, at the rate of one bit per component channel, so as to form parallel words of kN bits, means for multiplexing the bits of the parallel kN-bit words into k parallel words of Nbits, and means for converting the parallel N-bit words from said binary code into parallel words of N' digits in said multi-level code. In the receiving part of a station, the system comprises means for distributing the bits of the parallel words of kN bits at the rate of one bit on each of the kN component channels, means for converting the parallel N'-digit words into parallel N-bit words of said binary code, means for forming parallel words of kN bits out of a number k of N-bit words supplied by the latter said converting means and means for demultiplexing the parallel kN-bit words into kN bits at the rate of one bit per component channel.

Time division digital transmission system

In the field of digital data multiplexing systems, the master rates assigned to the different channels are defined by the national Telecommunications Authorities. It may and actually does happen that the master rates differ in different countries. A direct bit per bit multiplexing system from a first low master rate to a second high master rate is proposed which allows demultiplexing the high-rate digital signal into intermediate-rate signals. The number of the synchro and stuffing bits in the high-rate signal and intermediate-rate signals being known, only the low-rate signals are stuffed in dependence upon the difference between their own timing and the local timing at the multiplexing station. Blank intervals are provided in the low-rate signals having the duration of the synchro and stuffing bits in the intermediate-rate signals divided by the intermediate-to-low rate ratio and blank intervals are provided in the intermediate-rate signals having the duration of the synchro and stuffing bits in the high-rate signal divided by the high-to-intermediate rate ratio. Synchro and stuffing bits are inserted in the intervals resulting from the bit per bit multiplexing of the blank intervals.

Digital multiplexing system

A device for ensuring in an intermediate station the transfer and the branch connection of at least one channel of plesiochronous numerical data multiplexed in accordance with a specific field of the transmission system, the intermediate station comprising a general emitting element provided with a clock and a general receiving element provided with a clock, said device comprising means for synchronizing in frequency and phase the clock of the general emitting element with the clock of the general receiving element, and an emitting path card which comprises a mixer whose first input terminal is fed by the signal of the information and justification bits and whose second input terminal is fed by the justification indication signal and whose output terminal, which is the output terminal of the path card, delivers a signal in which the first half of each bit is characteristic of the information and justification signal and the second half of the same bits is characteristic of the justification indication signal.

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Lannion, France

Patrick E Boutmy