Abstract: A synchronous demultiplexer at a receiving station of a TDM/PCM telecommunication system, operating on an incoming bit stream organized in frames of 32 time slots of eight bits each, comprises a pair of substantially identical random-access memories each having 32 cells loaded with consecutive octets in successive time slots of a frame period P' under the control of a writing-address generator, stepped by clock pulses CK' extracted from the bit stream, and unloaded at a similar but not exactly identical rate in successive time slots of a period P" under the control of a reading-address generator, stepped by locally generated clock pulses CK". Writing as well as reading addresses are fed to both memories simultaneously but the two memories are loaded in alternate frame periods P' and unloaded in alternate frame periods P" under the control of selection signals in the form of two square waves respectively derived from clock pulses CK' and CK".

Abstract: A plurality of binary counters, each consisting of a primary and a secondary counting chain, are stepped by respective trains of clock pulses of like cadence but indeterminate phase relationship. The several primary counting chains are provided on their input sides with respective correlation circuits and on their output sides with respective sync generators, either of which is used for a concurrent restarting of both chains upon the attainment of a full count. A selection signal establishes one of the primary counting chains as the master by unblocking its sync generator while blocking its correlation circuit, the opposite being the case in all the other counters which are controlled from the unblocked sync generator through their respective correlation circuits.

Abstract: A klystron oscillator has an input cavity resonant in a TM.sub.010 mode and a larger output cavity resonant in a TM.sub.OnO mode where n is an integer greater than 1, preferably equal to 2. The input cavity, with re-entrant bosses defining a buncher gap, projects into the output cavity to form one of two re-entrant bosses thereof defining a catcher gap.

Abstract: Three or more oscillators to be locked in phase with one another are interconnected in a closed ring and have individual feedback loops including respective frequency dividers designed to keep them in step with a synchronizing frequency, equal to a fraction of their own operating frequency, fed in through an associated multiplexer. The multiplexer has a first input receiving the stepped-down feedback frequency of the immediately preceding oscillator, a second input connected to the output of the associated frequency divider, and a third input energizable with an external reference frequency such as a carrier of a PCM of FDM system. Each multiplexer, in the absence of an external switching command which holds it on its third input, stands on its first input unless a control circuit associated with the immediately preceding oscillator detects a disparity between the two frequencies fed to that preceding oscillator via the feedback loop and the multiplexer of the latter.

Abstract: A subcarrier frequency-modulated with a message signal is heterodyned with a carrier from a crystal-controlled oscillator in a mixer whose output is fed to a filter eliminating one of the resulting sidebands. In order to compensate temperature-dependent fluctuations of the carrier frequency, a function generator produces a corrective signal which is added to the message signal in the input of the frequency modulator traversed by the subcarrier. The corrective signal varies as a quadratic or a cubic function of temperature, depending upon the type of cut used on the quartz crystal controlling the carrier oscillator, with a polarity determined by which of the two sidebands is passed by the filter.

Abstract: A sampling gate of a TDM telephone system, designed to connect a subscriber station to a trunk line during an allocated time slot, comprises a pair of bucking transistors of the same conductivity type (NPN) inserted between a live wire from the station and a corresponding "hot" conductor of the trunk line whose "cold" conductor, tied to the reference wire of the subscriber line, is grounded through an elevated resistance. During the allocated time slot, the two bucking transistors are rendered conductive by a timing pulse applied across their base/emitter circuits via a transformer while a connection leading from their bases to negative biasing potential is temporarily severed by an interposed FET which is cut off by the timing pulse applied to its gate electrode via a differentiation circuit.

Abstract: An electroacoustic transducer comprises a condenser of variable capacitance, responsive to acoustic waves impinging upon its plates, connected across a source of d-c voltage in a circuit of negligible ohmic resistance by way of two reactive impedance elements with reactances of equal frequency-dependent magnitude and opposite sign, specifically a positive and a negative capacitance, in series with each other. The negative-capacitance element is formed by an ancillary capacitor in the output of an impedance-inverting four-terminal network including an operational amplifier with resistive feedback. The output signal is taken off across one of the two series-connected impedance elements.

Abstract: A receiving station of a data-transmission system decodes an incoming pulse train in the shape of a differentially biphase-coded carrier wave whose cycles represent respective message bits; the wave undergoes a phase reversal at the beginning of every cycle in which the transmitted binary signal has the logical value "1" but does not change in phase when that value is "0." The received pulse train is differentiated to yield either one or two spikes during each cycle, one such spike invariably occurring in the middle of a cycle. Since only these periodically recurring spikes determine the instants at which the carrier wave must be sampled during decoding, a gate in the differentiator output is blocked during part of each cycle by a locally generated square wave which also controls the sampling.

Abstract: A receiving station of a data-transmission system, designed to decode an incoming pulse train in the shape of a differentially biphase-coded carrier wave whose cycles represent respective message bits, includes a phase detector responsive to a presynchronization oscillation preceding an incoming message. The presynchronization signal, in the form of a square wave of half the frequency of the carrier wave, is fed to a phase detector along with a locally generated square wave of carrier-wave frequency. The phase detector, comprising several cascaded flip-flops, determines the relative time position of the local square wave and the presynchronization oscillation with the aid of an Exclusive-OR gate in the input of the first flip-flop and emits a corrective signal shifting the local square wave by half a cycle whenever the leading edges of the latter wave do not coincide with the beginnings of half-cycles of the presynchronization oscillation.

Abstract: A resonant cavity of a microwave generator, such as a magnetron oscillator, is provided with a tuning piston which is displaceable between two terminal positions, corresponding to respective limiting frequencies, by means of a rotating crank-shaft whose eccentric portion is hugged by a nonrotatable follower ring suspended between two flexible wires or blades extending generally radially outward from diametrically opposite points of the ring. A yoke spacedly surrounding the ring is provided with two oppositely extending tubular arms in which the wires or blades are received with clearance while being fastened to the ends of these arms remote from the yoke; the tuning piston is rigidly connected with one of the two arms.

Abstract: A resonant cavity of a microwave generator, such as a magnetron oscillator, is provided with a tuning piston which is displaceable between two terminal positions, corresponding to respective limiting frequencies f.sub.1 and f.sub.2, by means of a rotating crankshaft to which the piston is coupled by a linkage including a pitman with a substantially linearly guided extremity remote from the crankshaft axis. The length p of the pitman, measured between the pivotal axes of its extremities, is related to the eccentricity e of the crankshaft by the expression ##EQU1## where q is the length of the stroke of the linearly guided extremity between its extended dead-center position and an intermediate position in which the operating frequency of the generator has its mean value (f.sub.1 +f.sub.2)/2. With this dimensioning, the frequency varies as a sinusoidal function of the crankshaft angle and is therefore proportional to the output voltage of an angle sensor coupled with the crankshaft.

Abstract: A self-balancing d-c/a-c converter comprises a transformer whose primary winding is split into a pair of symmetrical halves each connected in series with a respective transistor and an associated resistor across a supply of direct current. A differential amplifier, with inputs connected across the two resistors through a pair of low-pass filters, generates an unbalance signal d in the form of a voltage of either polarity which is additively and subtractively superimposed upon a reference voltage e to provide two control signals e+d and e-d fed to respective inputs of two comparators. Two synchronized signal generators produce a sawtooth oscillation a and a square wave f, the latter having a period which is twice that of the former. Sawtooth wave a is fed in parallel to the other inputs of the two comparators while the square wave f and its complement g alternately unblock a pair of AND gates in cascade with these comparators.

Abstract: A transmission path for a pulse-type communication system comprises two flat outer conductors and one flat inner conductor separated from one another by layers of dielectric material such as Teflon. The maximum effective thickness of the conductors is on the order of magnitude of the penetration depth of the current. The stack of conductive and nonconductive layers is flanked by two ferrite strips of the same height as the stack and in contact therewith, these strips serving to gather the laterally emanating lines of force into closed loops alongside the stack. At least one of the strips may be subdivided into sections separated by gaps through which branch leads can extend into contact with the flat conductors.

Abstract: For the transmission of binary signals in a succession of pulse cycles, a message pulse generated at a transmitting station during the first half of a cycle is inverted in the second half thereof before being sent over a line to a remote receiving station. There a synchronization signal is extracted from the incoming pulse train to produce a series of equispaced timing pulses normally occurring in the middle of the second half of each cycle. This incoming pulse train is subtractively combined with a replica thereof, relatively phase-shifted by half a cycle, to produce a ternary pulse train which is sampled by the timing pulses to reproduce the original binary pulse train. An error-rate sensor shifts the series of timing pulses by a half-cycle upon detecting any significant disalignment between them and the correct sampling instants.

Abstract: A peripheral unit such as a teletypewriter, associated with a data processor but operating at a relatively slow rate so as to require an interruption of the processor's program when transmitting data, communicates with the processor through an interface unit comprising a sequential network switchable from a quiescent state (D) to an active state (C) via a preparatory state (A) and an intermediate state (B). The sequential network assumes its preparatory state (A) upon the appearance, at the interface unit, of an input/output instruction read out from a program store in the processor and addressed to the associated peripheral unit; the changeover to the intermediate state (B) occurs immediately thereafter if that peripheral unit emits a "data ready" signal (s).

Abstract: A central processor of a telecommunication system, operating in a time-division mode, communicates with a peripheral unit through an interface unit including a receiving section and a transmitting section. A control component in the receiving section commands the writing of a signalization messages from the processor in a random-access memory, in cells addressed by counting signals from the peripheral unit in respective time slots of a scanning cycle. The stored signalization messages are read out, in the first half of a time slot immediately preceding the one in which they are to be utilized in the peripheral unit, for relaying to that unit; the second half of each time slot serves for the writing of new messages in the memory or for the deletion of previously stored messages in response to cancellation signals from the peripheral unit, all with the aid of instructions extracted from a microprogram store in the control component of the receiving section.

Abstract: An interface unit, intervening in the high-speed transfer of data between an associated peripheral unit and a central memory of a processor, comprises a first and a second binary counter CM.sub.1, CM.sub.2 for the respective storage of memory addresses and of the number of data words to be read out from or written into a series of such addresses. In response to the arrival of an input/output instruction from a program memory of the processor, intended for the associated peripheral unit, a first sequential network RS' controls the loading of these counters with a starting address and an initial word count; if no other peripheral unit takes precedence, a second sequential network RS" then causes transmission of the contents of the first counter CM.sub.1, during successive cycles of a microroutine established by a control unit of the processor, to that processor followed by the readout (or write-in) of data words at the corresponding addresses, with incrementation of the address in counter CM.sub.

Abstract: A self-exciting oscillator comprises a klystron with an input cavity and an output cavity, interconnected by a feedback port, which resonate at fractionally different frequencies in the microwave range. The output cavity, alone, is tunable to vary the operating frequency within a range of about .+-.2%.

Abstract: A rotary line selector of a telephone exchange has a wiper, connected to a test wire, coacting with a multiplicity of bank contacts divided into ten decadic groups that are separated by rest positions in which the wiper may come to a halt after selection of a decadic group by the penultimate digit of a call number, the selector being then driven in response to the final digit to choose one of the ten outgoing lines whose test wires are tied to respective bank contacts of that group. If the called subscriber can be reached through a line multiple, selection of the first line--if the latter happens to be busy--brings on an ancillary relay X which connects a previously charged capacitor C in a sensing circuit including a common lead tied to the test wires of all the other lines of the multiple, operation of another ancillary relay V' then actuating a driving relay V for resumption of selector rotation while switching a test relay P from the wiper to the sensing circuit. When another line of the multiple.