Abstract: A supervisory method for a digital optical submerged transmission system in which a multi-bit test signal is detected by a repeater while receiving a loop-back signal for causing loop-back condition, and the mix of the bits of the test signal is changed to change a d.c. level derived in the repeater from the test signal. This is compared with a local reference level and after comparison a sign change is indicated the loop-back condition is either enabled or disabled and that event is detected enabling the required input or output level of the repeater to be checked.

Abstract: A protection circuit for a push-pull amplifier includes two sensing transistors arranged in respective feedback circuits. The output signals of such sensing transistors, which are indicative of the output voltage, are used to limit the output current of the amplifier in such a manner that the output current is limited to a first threshold decreasing with a steeper slope as a function of the output voltage of the amplifier between predetermined two output voltage values, and a second threshold decreasing with increasing output voltage at a lesser slope above the higher one of the two predetermined output voltage values. This characteristic response can be overridden by appropriate circuitry so long as the temperature of the amplifier is below a predetermined maximum value, so as to make the output current threshold independent of the output voltage.

Abstract: In a power supply consisting of parallel-connected converters, each of the converters includes a current sensor. One terminal of each current sensor is connected to one terminal of each of the other current sensors. The other terminal is connected to the converter's pulse-width modulator through a limiter. If any of the converters fails, the limiter ensures that only a small, limited change occurs in the output voltages of the other converters which is permissible in most cases.

Abstract: An optical communication system including at a transmitter a semiconductor laser (2) and at a receiver a photodetector (3). Intermediate the transmitter and the receiver is an optical frequency discrimination (4), e.g. a Fabry-Perot resonator. The laser (2) is operated at a substantially constant average power level above the lasing threshold. Superimposed (5) on the substantially constant bias current is a low level modulation signal. The level of modulation of the bias current is sufficient only to cause an effective change in the optical frequency of the laser output without causing the laser oscillations to change from one longitudinal mode to another. The discriminator (4) is tuned to one of the frequencies thus produced.

Abstract: The arrangement comprises a plurality of correlation means coupled to the received signal with the received signal being clocked into each of the plurality of correlation means by a different one of a plurality of different phased clocks with the different phased clocks occurring at a predetermined different time uniformly spaced over a given time interval and integration means coupled to each of the plurality of correlation means to provide the indication of the time of arrival of the received signals.

Abstract: The arrangement comprises N signal channels each responsive to a different one of N signals where N is an integer greater than one. Each of the N signal channels includes a sampling circuit to sample the associated one of the N signals by a different one of N phase clocks with each of the N phase clocks sampling a different one of the N signals at a predetermined different time uniformly spaced over a given time interval. A delay means is coupled to each of the sampling circuits to time align the outputs of each of the sampling circuits so that all sampled signal pulses are time shifted consistent with the associated sampling clock phases. A correlator is coupled to the output of each of the delay means to correlate the samples of the N signals with a reference signal. The output of the correlators are integrated to provide the indication of the time of arrival of the N signals.

Abstract: A pulsation damper includes a housing which bounds an internal space and two substantially coaxial openings at opposite axial ends thereof. A movable wall sealingly subdivides the internal space of the housing into a fluid-containing compartment which is supplied with the fluid whose pulsations are to be damped through one of the openings, and a gas-containing compartment which communicates with the other opening. An actuating rod is connected to the movable wall for joint movement therewith and has an extension portion which extends into the other opening and has an annular recess and forms a sealed interface with the surface bounding the other opening. Two annular channels open onto such surface at axial spacings from the recess in an equilibrium position of the movable wall.

Abstract: A diaphragm pump pumping arrangement includes two diaphragm pumps which are arranged and operate in tandem. Each of the diaphragm pumps includes a housing and a movable wall that includes a flexible diaphragm and subdivides the interior of the respective pump housing into a pumping chamber and an actuating chamber. An air distributing control arrangement interposed between and connected to the pump housings includes a spool valve movable in a bore of an aluminum casing of the control arrangement between two end positions in which it alternatingly achieves the admission of the compressed air into one, and discharge of the air from the other, actuating chamber.

Abstract: An enclosure includes a closed housing having a wall dividing the housing into a first compartment containing a high voltage portion of the power supply and a second compartment containing a low voltage portion of the power supply. A dielectric fluid fills the first compartment and partially fills the second compartment. A first check valve disposed in the wall enables fluid to flow from the first compartment to the second compartment during a temperature increase to compensate for expansion of the fluid in the first compartment. A second check valve disposed in the wall, in communication with the fluid in the second compartment, enables the fluid to flow from the second compartment to the first compartment during a temperature decrease to maintain the first compartment full of the fluid.

Abstract: A check valve particularly for use in large-volume applications includes a self-contained pressing unit which is mounted on a common pivot with the valve member in the outlet compartment of the valve housing and presses the valve member towards its closing position in which it sealingly contacts the valve seat. The pressing unit includes an elongated support member and an L-shaped pressing member which are mounted on a bearing sleeve for angular displacement relative to one another about the axis of the bearing sleeve. A buckling-type spring is mounted between a free end portion of the support element and the region of merger of the two legs of the L-shaped pressing member, the spring urging the pressing component away from the support component, and against the valve member upon installation on the pivot. The spring characteristic is such that the spring force initially rapidly increases, than drops precipitously and then remains substantially constant over a substantial range of deformation of the spring.

Abstract: The sealing element of a butterfly valve includes a rigid support ring, and an elastically yieldable sealing ring which partially embeds the support ring within itself. The sealing ring has an inner portion which is juxtaposed with the inner periphery of the support ring, and two end portions which emerge with the inner portion and extend therefrom in the radially outward direction in juxtaposition with respective axial end faces of the support ring. At least one of the end portions of the sealing ring terminates before it reaches the outer peripheral surface of the support ring, so that it exposes an annular zone of one of the axial end faces of the support ring. An annular, circumferentially complete, projection of the valve body extends into the passage at the downstream end thereof as considered in the direction of fluid flow through the passage in the fully open position of the valve member.

Abstract: A fiber optic direct current coupled data transmission link having a response extending to dc by using a dc coupled receiver and a modified frequency response to avoid data width distortion which allows the dc coupled receiver to work over a wide range of input signal levels.

Abstract: An apparatus for frequency-modulating telecommunication carriers with baseband signals includes an arrangement for generating two quadrature-related baseband signals in two separate channels, wherein each of the quadrature-related baseband signals is a sinusoidal function of the instantaneous angle of the message signal to be transmitted. The apparatus further includes an arrangement for producing a frequency-modulated carrier from the quadrature-related baseband signals, this arrangement including a device that provides two quadrature-related carrier-frequency waveforms, two mixing devices each for individually mixing one of the quadrature-related carrier-frequency waveforms with one of the quadrature-related baseband signals in one of the channels, and a combining device which combines the output signals from the two channels into a single frequency-modulated carrier-frequency output signal.

Abstract: The transmitter-receiver module includes a four-terminal coupler (2). An oscillator (1) and two diodes (4, 4') are connected to three of the terminals, while the fourth is connectable to an antenna (3). The diodes are used as a modulator during transmit, and as a mixer during receive. When transmitting, the oscillator is used as a signal source, and when receiving, it is used as a local oscillator. The module is implemented using fin-line technology. Several ways of realizing the oscillator are given.

Abstract: A method of detecting the presence of flaws in wire as it passes through a wire drawing die involves monitoring the output in the megacycle range of an acoustic sensor attached to the drawing die.

Abstract: The moving coil (voice coil) of the loudspeaker is so designed that the loudspeaker will become suitable for automatic production. For this purpose, the moving coil is positioned on a coilform, and as a connecting line extending to the ends of the moving coil there are used flexible ribbon conductors secured to a plastics carrier.

Abstract: A coding and decoding arrangement situated between and connected to digital and analog telecommunication lines includes a plurality of signal processing components which are arranged in respective receive and transmit paths and which process incoming digital signals and convert them into analog signals, and convert outgoing analog signals into digital signals and process the latter. A plurality of multiplexers is provided, each arranged ahead of one of the components in the respective receive and transmit path, and having respective test paths connected thereto. The multiplexers can be switched by control signals such as to selectively form test routes through the arrangement, each test route including a different combination of the components, so that testing signals can be sent through such components via the test routes for testing the performances of such components.

Abstract: The oscillator includes a two-terminal device (1) as an active element and an impedance-matching network (4) for matching the two-terminal device to a load (A). The impedance-matching network is formed by a coupler (4) having four terminals (2, 3, 7, 8) two of which (7, 8) are terminated with impedances (5, 6) whose values are chosen depending on the output power or frequency to be adjusted or are varied as desired. Another of the terminals is connected to the active two-terminal device (1), and the fourth terminal (3) is the oscillator output.

Abstract: An optical transmission system comprises a light source, which may be coherent or incoherent, a first optical interferometer wherein light from the source is modulated, an optical path, which may be either free space or an optical fiber, along which the modulated output of the first interferometer is propagated, a second interferometer wherein light received from the optical path is demodulated, and a photodetector to which the demodulated output is applied. Typically the first interferometers is a Fabry-Perot etalon, the length of the resonant cavity of which can be altered to modulate light applied thereto.

Abstract: The device is associated with a logic apparatus thereto four lines are coupled for transmitting logic data having a predetermined frequency and supplying at the output thereof a multiplexed signal having a frequency which is four times the mentioned frequency and responsive to the control of the subject device which comprises a binary digit pseudo-random sequence source and four Exclusive-OR logic circuits coupling said source to said apparatus in such a way as to define for said multiplexed signal a pseudo-random sequence having a period 2.sup.7 -1, as the tributary data is T1=T2=T3=T4=".0.".