Abstract: The invention concerns a level regulator for a frequency division multiplex group, having a variable gain network controlled basically by the observing of the amplitude of a pilot wave contained in the multiplex group, comprising a digital filter preceded by a sampling device and an analog-digital converter for extracting the pilot wave from the multiplex group downstream from the variable gain network, a calculation circuit connected to the digital filter for determining a number which is a function of the level, over a predetermined interval of time, of the pilot wave at the output of the filter, and a digital comparison element which compares that number with a reference value with a view to generating a control signal for the said network. In a particular embodiment of the invention, the multiplex group is transposed towards the low frequencies before being digitally processed.

Abstract: A switching station for a telecommunication system, operating with pulse-code modulation, serves a multiplicity of incoming and outgoing PCM channels each consisting of a succession of 8-bit words cyclically interleaved with the words of 31 other channels in an assigned time slot of a 32-channel frame, 32 such frames being received and transmitted over as many signal paths forming a frame group. There are n incoming frame groups and n outgoing frame groups with synchronized bit phases in all the spatially separated channels thereof. A central processor controls the concurrent storage of all the incoming bits of a given phase in n pairs of 16-section input memories, each memory section consisting of 8 stages for the bits of a respective word from an incoming channel on a receiving signal path.

Abstract: A processor equipment has an input highway connected to receive a multiplex signal from a number of peripheral devices such as multiplex units time division multiplxing telephone handsets. A counter is arranged to scan the devices for a processor interrupt signal and upon the occurrence of such a signal the counter is inhibited to enable the processor to take the appropriate action for the interrupting device, e.g. apply a dial tone. If one of the peripheral devices becomes faulty a store memorizes the fact that on a previous scan the device produced a non-valid interrupt signal and causes the address of a predetermined other peripheral device to be written into the counter at which scanning is to recommence.

Abstract: Most PCM systems provide non-blocking switching, with a channel per each terminal equipment being provided. In other words, they are dedicated channel arrangements. The present invention relates to PCM system using a method and arrangement which is a condensation of the required channels provided to time division switching by distribution of the channels instead of the usual dedicated channel method. In this system, a channel memory is created and provided to provide for control of which terminal equipments are allotted which channels (on a per call basis).

Abstract: A line interface unit for a digital local office for telephonic communication has a circuit connected to telemeter low-frequency signals around a line, alternating current, hybrid coupler and reinsert the same signals in the call path at the input to an analog-to-digital encoder that is coupled to a time division switching network. Each interface unit also includes circuits for multiplexing various line unit, digital, status signals with coded call signals and for demultiplexing line unit, digital, control signals from coded call signals. That network is utilized by an office common control for interconnecting various call paths with one another and for interconnecting the common control with the line interface units as required. The common control includes a time-shared digital filter for processing the telemetered signals for various office purposes.

Abstract: A communication system has at least one supervisory station and a large number of repeater stations spaced along a four-wire two-way transmission line. A number of repeater stations are selected at equal intervals along the line to have a coupling network coupling test signals from the first pair of wires in the transmission line to the second pair of wires which differs from the coupling network of the remainder of the repeater stations. To locate a fault, test signals in the form of pulses are sent from the supervisory station to the repeater stations. At each repeater station, if operative, the received test signals are coupled to the second pair of wires for retransmission back to the supervisory station.

Abstract: In a multi-channel multiplexed system, each signal-receiving input channel has a DC blocking capacitor. One of the input channels to the multiplexer is grounded making this channel a test channel. A signal-conditioner-and-amplifier network (SCAN) couples the multiplexer output to a utilization device. The spurious voltage developed across the capacitor in the test channel combined with the offset voltage across the SCAN will be substantially the same as each one of the spurious voltages developed across the capacitors in the other input channels in combination with the SCAN offset voltage. A sample-and-hold circuit consisting of a series capacitor and a normally ungrounded shunt switch is connected between the output of the SCAN and the input to the utilization device.

Abstract: A pulse-code modulation transmission system having reduced redundancy and high transmission quality utilizes a variable companding law and variable number of bits per sample both of which vary in accordance with the type and/or short-time volume of the signal associated with a particular talker as well as with the type and/or short-time volume of all of the signals associated with all of the talkers handled by the transmission system. The system utilizes the envelope or modulating signal for the speech signal to provide a companding law which varies as the talker varies and, for a particular talker, as the short-time volume of that talker varies, so that redundancy can be reduced without impairing transmission quality. This companding law adapts itself to the vowels, consonants and syllables of the word in accordance with their volume in order to optimize the signal to quantizing noise ratio.

Abstract: A group frame synchronization system establishes the frame synchronization to a plurality of time-division multiplexed digital signals by the use of a common synchronization code pattern. The common synchronization code pattern and mutually time-shifted codes of identical pattern are respectively inserted at the transmitting end into vacant time slots of the respective digital signals. At the receiving end, the group frame synchronization signals are extracted and fed to an exclusive OR circuit whose output signal is applied to the group frame synchronization circuit.

Abstract: A system for detecting the occupancy of the channels of a telecommunication network and monitoring the transmission of signals, wherein the signals on a telephone line are sampled to detect the quasi-periodic nature of speech signals for long enough to differentiate them from noise signals of a random nature.

Abstract: A Space Division Multiple Access (SDMA) Communications satellite system which utilizes a pair of communications satellite relays having a communications link between them. Each satellite includes a plurality of receive spotbeam antennas which are selectively connected to a plurality of transmit spotbeam antennas by an on-board switching matrix under control of an on-board oscillator. Each spotbeam antenna communicates with a different geographical zone which includes one or more earth stations. Each station may communicate with all other stations in the system including those within the field of view of the spotbeam antennas aboard the other satellite. In order to maintain synchronization between the satellites, a designated reference station transmits a reference synchronization burst of four sequential unique words to the satellite within its field of view. The reference burst is related to the other satellite and back again to the first satellite where it is relayed back to the reference station.

Abstract: A time division multiplex private automatic branch exchange includes a common interchange bus, and as many sampling circuits and associated recirculating shift registers as there are telephones. Two telephones are connected to each other through the bus when time-slot-determining outputs of the respective two shift registers actuate transmission gates in the respective sampling circuits. Other pairs of telephones may be connected to each other during other time slots. Additional sampling circuits and shift registers are provided to connect dial tones, ring tones, etc., over the bus to appropriate telephones in the same time division sampling fashion. All sampling connections are made under control of a computer by loading information into time slot stages of the shift registers.

Abstract: There is disclosed a two-way cable system in which the deliberate introduction of continuous upstream message interference at any subscriber terminal does not destroy the efficacy of the system. Each subscriber terminal is coupled through an interface unit to the cable, and the interface unit permits upstream transmission of a message from the respective terminal only following recognition by the interface unit of the downstream transmission of the address of the respective terminal. Because the interface units are located off the premises of the subscribers, a deliberately introduced interference signal on a subscriber line cannot reach the cable except during the respective time slot of the subscriber.

Abstract: A digital speech interpolation (DSI) system advantageously utilizes speech inactivity time to reduce the bit rate by compressing digital characters from a plurality of trunks onto a lesser plurality of channels. A signaling arrangement is typically employed therein to signal a receiver as to the activity of a trunk. If the number of active trunks exceeds the number of channels, an overload may exist. Known arrangements for mitigating overload typically include apparatus responsive to an activity signal for truncating one or more bits from the digital characters and for transmitting the truncated characters. Unfortunately, quantization noise is increased and digital precision decreased in such arrangements. The hereindisclosed system includes an improved automatically adaptive arrangement for advantageously incorporating nearly instantaneous companding (NIC) and priority trunk rotation in a plurality of frames, called a multiframe.

Abstract: Time multiplexed data transmission system in which P.C.M. data words (bytes) derived from speech signals of telephone component channels (telephone inputs) and P.C.M. signalling words derived from the signalling state of said telephone component channels (inputs) are respectively time multiplexed in data time slots and signalling time slots of a frame to form a composite multiplex channel or frame. The signalling time slots of successive frames form a multiframe format. In the intermediate stations inserted along the transmission path over which the resultant multiplex frame is transmitted, the input channel data and signalling states can be extracted or inserted. Each intermediate station comprises a device reconstituting (regenerating) the incident frame and a local frame time base, self driven and synchronized by the incident frame reconstituting device. The contents of incomng data time slots and signalling time slots are stored in a frame memory.

Abstract: The invention comes within the field of multiplex digital transmissions. It concerns a device for multiplexing n digital plesiochronous trains into a more rapid digital train, comprising n channel elements for synchronizing together the plesiochronous trains by adding of extra bits called "justification bits" and a multiplexing element for sending out, from the synchronized trains, the rapid multiplex train. According to the invention, each of the channel elements comprises means for inserting, at a determined location place in the corresponding synchronized train, a justification request signal, the said multiplexing element comprising means for reading each of the n justification request signals and controlling the insertion in the multiplex train of justification indicator bits and means for giving, if required, to the corresponding channel element, the permission to effect a justification.

Abstract: A serial looped transmission system is disclosed which includes a central terminal and a number of remote terminals for two-way communication between the various terminals on a single looped transmission facility. Each terminal includes multiplexing and demultiplexing equipment for taking signals off and placing signals on the common transmission line.Failures in any link of this system cause the entire system to fail. Loopbacks placed at each terminal permit restoration of service to the operative portion of the system. Testing the system in order to place such loopbacks is accomplished by common timing and testing equipment at the central terminal which takes into account the variances in start-up time for different sizes of the operating system. Loopback instabilities due to timing variances are overcome by placing the central terminal in overall control of the loopback sequence.

Abstract: A digital multiplexer for transmitting control, signaling and speech information in digital form between a central telecommunications office (CO) and a plurality of remote terminals. The system serves a plurality of lines at the exchange and couples those lines to subscriber stations associated with those lines through a digital span line such as the generally known Tl line between a CO terminal and the remote terminals. A maximum of 32 channels are provided using continuously variable slope delta modulation, with the modulation and demodulation being performed in line circuits individual to each line being served. A time division concentration stage enables the system to service 128 lines over the 32 channels with each channel having a memory position for storage of line address information.

Abstract: A large number of terminals are connected to a central computer in a loop utilizing a very high speed transmission medium. A sequential stream of message blocks are provided for transmission by the loop. Each message block includes a first portion specifying a terminal address, and a second portion for specifying information data. Each terminal interrogates the address portion of each message block and responds to its own address by either reading the data portion of the message block or loading into the data portion messages to be transmitted. By generating a continuous stream of message blocks, one for each terminal, and using a randomizing scheme for address generation, it is possible to connect a large number of terminals to a data communications system while maintaining a reasonable response time.

Abstract: Bit rate compression in a digital communications system is provided by transmitting voice information from n telephone circuits over the capacity conventionally allocated for transmission of voice information from n/2 circuits without appreciable degradation in quality. Alternatively, a doubling of the number of voice circuits may be provided with transmission at the same bit rate required for conventional digital transmission of voice information. Each frame period, at the transmitter, all n circuits are serviced and, utilizing a predictive encoding scheme, only unpredictable samples in the given frame are transmitted over the available channel capacity. A sample assignment word (SAW), which identifies the circuits corresponding to the unpredictable samples, is transmitted therewith.