Abstract: The recognition method is applied to visual telephony image coding. Matrices of digital samples relevant to the individual frames of the video transmission are submitted to a first processing whereby the foreground region containing the figure is identified. The information concerning the elements of such a region is then processed by edge recognition algorithms to detect a group of elements possibly belonging to the contour. The group of elements is analyzed to select a sequence of elements distributed on the average along a line. The sequency of elements is processed by a neural network to build up the continuous contour which is then coded.

Abstract: A node for a fast packet-switching network in optical-electrical technology comprises an optical switching matrix and electrical control equipment which processes the signalling and the information packet headers. More particularly, the control equipment updates the label and, depending on such a label, searches for the routing through the node. A centralized node controller processes the signalling, while a distributed processing system processes the packet headers and routes the packets through the network. For all communications in progress, the distributed processing system periodically forwards routing requests to an electrical self-routing switching matrix associated with the optical matrix. When a connection path has been found between an input and an output of the electrical matrix, the same path is reproduced in the optical matrix and the packets are transferred to the node output through the optical matrix.

Abstract: The interferometer makes use of an acousto-optic device to perform a frequency shift of the beam sent along one of the interferometer branches, so as to allow the determination of the state of polarization by heterodyne radiofrequency detection. The acousto-optic device can be inserted downstream of the device for splitting the beam emitted by the source into the two beams sent along the two interferometer branches, or it can also act as the beam splitter.

Abstract: A communication system serving a number of nodes, each associated with a group of subscriber terminals, comprises a unidirectional bus bent into a loop to form a transmitting branch and a receiving branch respectively connected by an outgoing coupler and an incoming coupler to all the terminals of a given node. In each node a plurality of detectors on opposite sides of the outgoing coupler monitor the activity of the transmitting branch to determine whether the bus is free from any signal carrier originating at an upstream node, or generated at the node considered, and is thus available for voice or data packets to be sent out. Each terminal includes a receiving unit, responsive to a pre-engagement packet addressed thereto via the incoming coupler, which starts a local time base to establish a succession of frames encompassing each a number of time slots allocated to active speech channels in a voice period of a frame; the remainder of each frame is available for data transmission.

Abstract: A phase-locking network at the receiving end of a transmission channel carries an incoming wave of predetermined frequency matching the operating frequency of a local oscillator the incoming wave and the locally generated oscillations being fed to respective inputs of a phase comparator producing a control voltage delivered through a low-pass filter to the oscillator for reducing any existing phase difference. The signal path between the phase comparator and the oscillator includes one or more nonlinear impedance elements, either within the filter or in cascade therewith, which lowers the effective series resistance of the path in the presence of a high control voltage and thereby increases its bandwidth during an acquisition period as compared with steady-state operation.

Abstract: A call monitor for a telephone exchange, including a processor intervening in the establishment of a connection between associated line links with the aid of a switching network, comprises a first memory storing information about each line link and a second memory containing codes that identify all possible states of a connection of interest to the processor along with all intervening conditions termed evolutions. During a time slot allocated to a particular line link, a multibit comparator receives data from the first memory concerning a connection involving that line link, along with updating information from the line link itself, on one set of inputs and further receives, on another set of inputs, a succession of evolutionary codes read out from the second memory until a match is detected; the read-out is then terminated and an instruction, if required, is sent to the processor and/or to the switching network.

Abstract: Switching criteria are transmitted over a plurality of trunk lines to a central office of a telecommunication system in the form of a set of binary signals modulated on three carriers for each trunk line, the triads of carriers being cyclically sampled and demodulated. During each sampling interval t.sub.i allocated to a particular trunk G.sub.i within a cycle, a locally generated identification code of that trunk is transmitted to each of three sections of a read-only memory MS, each memory section permanently storing four different threshold values for the length of "on" signals (1) and "off" signals (0). Integrators IN, rejecting spurious changeovers from one type of signal to the other, feed respective counters CT via respective coincidence circuits CFR which receive from a register MG the bits of the preceding cycle and reset arithmetic units .sigma.