Abstract: A multiplicity of peripheral units are consecutively scanned, in respective phases of a recurrent operating cycle, by a central unit including a processor for incoming and outgoing data. The processor is connected to a programmer emitting a series of binary instructions during each phase, the instructions being stored in a read-only memory from which they are read out during respective subphases of each phase under the control of an address counter, the last instruction of a series carrying a characteristic bit which advances a phase counter and causes a switch of the central unit to a different peripheral unit.

Abstract: A system for the floating energization of a balanced load from a remote power supply via a pair of conductors, e.g., for feeding operating currents to repeaters of a telecommunication link, includes a circuit breaker controlled by an open-circuit sensor and an unbalance sensor through a memory unit provided with a pair of storage circuits. These circuits, designed to store a malfunction signal emitted by either of the two sensors until the arrival of a resetting signal, inhibit each other to prevent the registration of more than one malfunction at a time.

Abstract: A modular connector, to be assembled with other such connectors into a switching frame designed to interlink incoming and outgoing lines of a telecommunication system, comprises a flat prismatic housing of generally rectangular outline with a bank of input terminals and a bank of output terminals fitted into a pair of recesses on its opposite longitudinal edges. Leads extending from the two terminal banks within the housing are bent to emerge at a major housing surface overlain by a printed-circuit board whose conductor strips connect them with two further sets of leads emerging from the same major surface adjacent one of its transverse edges, the leads of these letter sets extending into a junction box attached to the housing along that transverse edge. Within the junction box, normally closed by a hinged door, contacts tied to the two sets of leads can be selectively interconnected or, if desired, extended to testing equipment.

Abstract: A coupling network at the junction of several multichannel TDM/PCM links comprises a pair of switching networks each including a set of input group units receiving incoming messages from respective PCM links, a set of output group units transmitting outgoing messages to respective PCM links, and a switching matrix interconnecting the two sets of group units. The bits of a code word representing an incoming message sample, arriving at a line unit individually associated with the respective PCM channel, are delivered to the corresponding input group unit during a receiving period, are read out during a transfer interval via the switching matrix to the output group unit for which they are intended, and are thence fed to the proper line unit during a transmitting period.

Abstract: A telephone exchange linked via PCM channels with subscribers engaged in a conference call includes switching circuits for transmitting to each participating subscriber, during an assigned time slot, the albegraic sum of the digitized voice-current samples from all the other participants. The digitized samples are logarithmically coded, each code consisting of a polarity bit, three range bits and four quantum bits; in order to facilitate correct addition or subtraction of the quantum bits of two codes to be summed (unless these codes signify the two lowest-ranking ranges), according to whether their sign bits are identical or different, the quantum bits of a lower-ranking code are shifted in a register toward less significant bit positions in which they would have their original numerical weight when prefaced by the range bits of the higher-ranking code.

Abstract: Two sets of line terminals in a pair of PCM head stations are interconnected by a set of transmission channels via a number of cascaded relay stations each including a line repeater for each channel. A service link extends from an address generator in one head station to a monitoring unit in each relay station, the monitoring unit including a regenerating circuit for throughgoing address codes and further including a discriminating network which, upon detecting an address code identifying that relay station, sends a sinusoidal priming signal to all the associated repeaters. A predetermined PCM test code, e.g. one containing a certain number of consecutive zeroes, is simultaneously transmitted from the same head station over the channel containing a selected repeater to be checked which, upon coincidence of the test code with the priming signal from the associated monitoring unit, closes a loop for feeding back the test code to the originating line terminal.

Abstract: An electroacoustic transducer, such as a microphone or a telephone receiver, comprises a thermoplastic body with a central plateau surrounded by an annular recess from which an elastic ring projects slightly above the plateau to support a membrane in the form of sheet-metal foil carrying a piezoceramic layer. The body is overlain by a thermoplastic cover which has apertures for the passage of sound waves and is formed with an internal annular rib registering with the elastic ring to clamp the rim of the membrane therebetween. The body, the cover and a thermoplastic base are joined together by ultrasonic welding.

Abstract: Four bit streams arriving simultaneously over respective incoming lines at a transmitting terminal, connected via a PCM link with a remote receiving terminal, constitute recurrent lower-order frames whose bits are to be interleaved in a composite higher-order frame to be sent on to the remote terminal for redistribution over four outgoing lines. The bits of each incoming bit stream are cyclically written in an 8-stage buffer register at their rate of arrival, the contents of the register stages being read out at a higher rate to allow for the interpolation of ancillary bits constituting supervisory signals. Each higher-order frame consists of four subframes in which the message bits from the contributing bit streams are preceded by one or more ancillary bits; the latter include a discriminating bit in each of the last three subframes indicating whether or not a further bit in the fourth subframe is a stuffing bit or a message bit. The insertion of a stuffing bit, i.e.

Abstract: An incoming bit stream of a first bit frequency, divided into a succession of n-bit words, is converted into an outgoing bit stream of a second bit frequency with the aid of two n-stage buffer registers alternately loaded by two sets of interleaved writing pulses, on every n.sup.th cycle of the first bit frequency, with incoming words which are alternately read out on every n.sup.th cycle of the second bit frequency by two sets of interleaved reading pulses. A logic network detects the coincidence of a reading pulse from one set with either of two guard pulses immediately preceding and succeeding, respectively, each writing pulse of the corresponding set; upon such coincidence, a switching network transposes the two sets of writing pulses to restore an original relative pulse position in which the reading pulses of each set occur substantially midway between writing pulses of the same set.

Abstract: A marker controlling the establishment of connections between local subscriber lines and inter-office links, via an associated line concentrator/distributor, comprises a link allocator, a signalization unit and a service unit. The link allocator responds to requests from a local subscriber line, transmitted via a line finder, or from a remote exchange, arriving over a common signal path, to control the line concentrator/distributor for connecting that local line to an available link or a designated link to a selected line. The signalization unit coacts with a respective two-way coupler in each link, in a time-division mode, to pick up outgoing dial pulses for transmission via the common path and to transmit switching instructions from that path to the engaged subscriber line. The service unit, communicating with both the link allocator and the signalization unit, receives and sends out information relating to possible malfunctions or alarm conditions.

Abstract: A storage network co-operating with a marker comprises a shift register whose stages are loaded in parallel with the digits of a call number received from a local subscriber, the first digit or digits of that call number being read out to an associated marker as an identification of a remote junction to which the call is to be extended via a transmission path selected under the control of that marker. When the marker has received enough digits to perform the switching operation linking the subscriber line with the selected transmission path, it activates a pulse generator which energizes an output lead in parallel with a counter whose reading is successively compared with the remaining digits still stored in some of the stages of the shift register. A comparator making this comparison, upon detecting a match between the pulse count and a stored digit, blocks the further readout of pulses to the output lead for an interdigit pause determined by a timer.

Abstract: A cable-TV system comprises a relay station linked by several HF cables with a distribution center feeding several subscriber stations via two-wire local lines, each HF cable carrying a respective TV program modulated on a common carrier. The distribution center comprises several switching matrices which are remote-controlled from respective subscriber stations for transmitting selected programs to any of them. Each subscriber station includes for this purpose a generator of a carrier frequency, above the band of incoming frequencies, which is pulse-modulated with the aid of a keyboard to identify the desired programs and is demodulated at a control unit tied to the associated switching matrix at the distribution center.

Abstract: A marker at a central-office terminal, controlling the establishment of connections between local subscriber lines and inter-office links via an associated line concentrator/distributor, includes a source of d-c test signals of reversible polarity connectable in a phantom circuit which extends from the central office via a transmitting and a receiving branch of a local line to a subscriber station tied to that line. The subscriber station has a master switch, establishing either an inactive position or a standby position, and a hook switch closable in the standby position to initiate or accept a call. Depending on the positions of these two switches, a current discriminator at the marker detects one of three current levels (zero, low or high) with either polarity of the test signal to determine whether a call can go through or whether an alarm condition exists.

Abstract: A marker at a central-office terminal, controlling the establishment of connections between local subscriber lines and inter-office links via an associated line concentrator/distributor, includes a test-signal generator connected via a two-way coupler to an outgoing branch of an engaged link, a first signal receiver connected by the coupler to an incoming branch of that link, and a second signal receiver inserted in a normally balanced phantom circuit formed by incoming and outgoing branches of a local line communicating with the link. Upon the establishment of a connection including such a link between two subscriber lines served by respective central-office terminals, an alternating test signal generated at one terminal must be detected with a predetermined minimum threshold by the first receiver but not by the second receiver of the other terminal before message transmission over this connection can be initiated.

Abstract: At the receiving end of a communication system utilizing a higher keying frequency F.sub.A and a lower keying frequency F.sub.Z for the transmission of information, a counter is stepped by clock pulses having a cadence F.sub.c >> F.sub.A. A train of short signal pulses, derived from the incoming wave and coinciding with the zero crossings thereof, is used to reset the counter whose output is delivered to a digital comparator also receiving a fixed reference number not less than and preferably equal to the count of clock pulses generated during a half-cycle of frequency F.sub.A. Whenever the output of the counter surpasses that reference number, the comparator has an output yielding, upon integration in a low-pass filter, a low-frequency wave which can be squared with the aid of a threshold circuit.

Abstract: An intermediate switching station or exchange, designed to establish temporary connections between calling and called lines of a telephone or other telecommunication system, is connected via n multichannel links to as many trunk terminals, the m channels of each link being represented by or converted into respective time slots of a PCM message frame of (m+2) time slots which also include a special time slot for switching codes. The code words from the special time slots of all incoming links are interleaved in a PCM switching frame of (m+2) time slots, with (n+1) such frames constituting a recurrent superframe carrying switching codes from all lines served by the exchange. A signalization coordinator converts the switching codes extracted from the superframe into signals for the actuation of a switching-control unit and reconverts response signals from that unit into switching codes to be inserted into outgoing message frames.

Abstract: A marker designed to control a switching circuit for extending an outgoing call to a remote junction, identified by a characteristic digit or digit combination at the beginning of a call number emitted by a local subscriber, includes a first and a second memory connected in tandem via an intervening decoder, the first memory having respective cells addressable by all possible digits and digit combinations forming part of the characteristic call-number portion. The code words stored in these cells are translated by the decoder into (a) a signal ni indicating a nonexisting junction, (b) a signal ci denoting an incomplete characteristic, or (c) a signal if addressing a cell of the second memory to select a transmission path leading to a fully identified junction.

Abstract: The outlying stations of a videotelephone system, adapted to communicate with one another through a central office, include each a video-reception section and a video-transmission section as well as an audio section provided with telephone equipment. A sync-pulse generator in the video-transmission section, comprising a crystal-controlled oscillator working into a pair of frequency dividers, controls the line-scan and frame-scan generators thereof as well as those of a remote station to which it is connected via an outgoing video line. A local sync-pulse extractor connected to an incoming video line controls the line-scan and frame-scan generators of the associated video-reception section.

Abstract: Analog-voltage samples to be transmitted in digital form over a communication channel, ranging between a lower and an upper limit V.sub.min and V.sub.max, are quantized in 2.sup.n levels with 2.sup.n/2 major quantum steps each subdivided into 2.sup.n/3 minor quantum steps represented by n-bit words, a group of n/2 bits of each word representing the major quantum steps and another group of n/2 bits representing the minor quantum steps. A converter at the transmitting end includes a first and a second constant-current generator, of high and low rate respectively, which are sequentially activated to discharge and to charge an input capacitor temporarily storing an analog-voltage sample to be digitized. The first generator rapidly discharges the input capacitor while an associated first pulse counter receives a series of forward-counting clock pulses, each pulse corresponding to a major quantum step, until the absolute value of the capacitor voltage drops below that of a predetermined reference voltage V.sub.

Abstract: A multiplicity of subscriber lines, originating at telephone stations equipped partly with dials and partly with keyboard-controlled multifrequency generators, are connected to pulse-responsive selection equipment by way of switching circuits which are under the control of respective key-signal detectors. Upon the operation of any multifrenquency generator, the latter emits a key signal which actuates the associated detector to switch that line to a conversion network wherein the incoming frequency combinations are translated into binary codes which are stored in a dynamic memory whence they are read out into an available binary/decimal converter. The stored binary codes are accompanied by a line address which enables a coupler to reinsert the selection signals, in the form of digital pulse trains, into the correct line with the aid of an associated interface unit.