Abstract: A circuit for providing a DC isolation between a pulse generator (E) and a load (CH) of the kind comprising a primary circuit (2), a secondary circuit (4) and at least one magnetization current elimination circuit (12) on the secondary side, characterized in that it is provided on the primary side with at least one unidirectional transmission circuit (15) which causes the pulses to pass and causes the magnetization current forcibly to be dissipated through the secondary in the circuit (12) for eliminating the said magnetization current and with at least one circuit (18) for attenuating the transient phenomena due to the commutation thus protecting the pulse generator (E).

Abstract: The present invention provides a transmission method denoted as the "color shift" method. Therein the composite color video signal, which is formed by a sequence of analog line signals, is sampled, as a result of which each analog line signal is converted into a time-discrete line signal formed by a plurality of line signal samples occurring at a rate f.sub.s, each sample being formed from the sum of a luminance and a chrominance signal sample. Thereafter, these time-discrete line signals are submitted to a scrambling operation in which, in accordance with a predetermined pattern, a number of line signal samples is, each time, selected from the line signal samples of a group of time-discrete line signals for assembling time-discrete auxiliary line signals. This selection is effected such that of all those line signal samples which together represent a given time-discrete auxiliary line signal, the associated chrominance signal samples all have the same polarities.

Abstract: A predictive encoding arrangement for use in a video digital imaging system wherein sequences of codewords are produced by a video signal source corresponding to sequential elements of a video picture, codewords for any given picture element being successively produced in successive picture periods. Codewords for the N picture elements of each picture period are stored in a picture memory. An encoder encodes the difference between codewords supplied by the video signal source and codewords read out from the memory, the encoded codewords than being decoded by a decoder and supplied to the memory for storage therein. A cyclic address counter operating at the codeword rate cyclically generates N-K memory addresses for storage of codewords in the memory, wherein N>K and K is the number of codeword periods for the encoder and decoder to produce a decoded codeword in response to a codeword from the video signal source.

Abstract: A method and apparatus for transmitting information from a number of transmitters to a receiver in a digital transmission system in time-division multiplex. So as to prevent to the greatest possible extent overlap of the information transmitted by the respective transmitters, the repetition rate of each transmitter is set in accordance with a unique identification number assigned to that transmitter. To keep the number of times each transmitter transmits as nearly equal as possible for all transmitters, each transmitter includes a circuit for generating inhibit signals which prevent transmission, the inhibit signals being generated more frequently in transmitters having shorter repetition intervals. The circuit can be realized using only digital circuits which can be implemented in a single IC.

Abstract: In accordance with the method, a supporting body (21) is formed by arranging contact members (3) so as to be adjacent and mutually parallel in a straight line and by moulding the contact members in a ribbon-like, flexible plastics body (1) while leaving contact portions (5) free. Subsequently, the body is rolled up so as to form a cylinder which is mounted in a bush (19) in order to form the supporting body (21). Prior to rolling up connection portions (7) of the contact member (3) are connected to conductors (9) of a cable (11). Finally, the assembly thus formed is enclosed by a plug body (25) which leaves the contact portions (5) free.

Abstract: The invention relates to a method of increasing the signal-to-noise ratio of a periodical electrical signal. In general, noise suppression of a periodical signal may be obtained by means of averaging a number of successive signals. In one embodiment of the present invention, the amplitudes of successive periodical signals are integrated for successive time periods which exclude various signal suppression subperiods. The suppression subperiods may be of variable duration, and are positioned beside each other in consecutive fashion. An overall integration value is also formed, by processing the amplitude of the signal without suppressing any portion thereof. From this overall integration value, the integration values associated with the various suppression subperiods are subtracted. The resulting difference signals are arranged in the same sequence as their associated suppression subperiods so as to produce an output signal having the same general waveform as the periodical signal.

Abstract: Cooker automatically controlling the heating process when bringing a food material to the boil on an electric hotplate and preventing it from boiling over at the end of the heating process. At the beginning of the heating process the power supplied to an electric hotplate can be set to a constant value which can be selected. A microprocessor continuously determines the rise in the temperature of the base of the pan as a function of time. At a pan-base temperature above about 70.degree. C. the actual value of the rise in temperature is compared with a present desired value and when deviations occur the heating power is switched over so as to approximate the actual value of the rise in temperature to the desired value. At a pan-base temperature above about 90.degree. C. a bending point in the temperature rise of the pan base is reached after which the heating power is switched off.

Abstract: An electromagnetic deflection unit for a cathode ray tube, comprising has at least one support (4) with a flange (8) at its narrow end (5), which has a tangential groove into which merge radial grooves (14). Two sets of deflection coils (18, 19) are wound directly onto the support (4). The turns thereof traverse the radial grooves (14), the turns of at least one set of deflection coils (18) being bent into the tangential groove. The radial grooves (14) have longitudinally extending portions (16), which are filled by the turns traversing them. The bottom portion (20) of the tangential grooves lie on the surface of an oval cylinder. The deflection unit has a high sensitivity, large axial sliding tolerance and permits correction of various kinds of deflection errors.

Abstract: A frequency multiplying circuit comprises a differential amplifier formed by two transistors whose emitters are connected by a current source to a low voltage supply rail, collector resistors are connected to a higher voltage rail as is also done with the base electrode of one of the transistors, the base electrode of the other of the transistors has an oscillator connected thereto. An LC resonant circuit coupled between the collectors of the two transistors and is tuned to select either the basic frequency of the oscillator or an odd harmonic thereof.

Abstract: An arrangement for converting an electric signal into an acoustic signal (y/t) or vice versa, comprises an electroacoustic transducer (2) and means (3) for reducing distortion in the output signal of the arrangement, which distortion is caused by the electroacoustic or acoustoelectric conversion performed by the transducer.The means comprise a non-linear network (3', 3" or 3'" in FIGS. 3; 43', 43" or 43'" in FIG. 4). The non-linear network is arranged for reducing non-linear distortion by compensating for at least a second or higher order distortion component in the output signal of the arrangement. The network may comprise at least two parallel circuit branches (15a, 15b in FIG. 3; 47a, 47b in FIG. 4). At least one of the circuit branches (15b in FIG. 3; 47b in FIG. 4) compensates for non-linear distortion of the second or higher order.

Abstract: The invention relates to an arrangement for restoring the L.F. content of a digital signal which has been conveyed through a high-pass filter. This is realized with the aid of a center clipper which is connected to the output of the filter. The restored digital signal can be taken from the output of the center clipper.

Abstract: In communications systems, such as cordless telephone systems, in which synchronizing signals are transmitted at predetermined intervals on a signalling channel by base stations to say portable, battery-powered receivers, the need to send separate station identification signals is avoided by the synchronizing signals being transmitted from a base station in accordance with a predetermined signalling sequence, for example a pseudo-random sequence, and the receivers using the sequence as a base station identification signal.

Abstract: An electroacoustic calling device comprising a piezoelectric transducer contained in a housing with an aperture therein through which sound is emitted. A closure member for controlling the size of the aperture, and hence the volume of emitted sound, is located in a recess in an arm pivotally mounted on the housing and is urged against the exterior surface of the housing by a projection at the bottom of the recess. The resulting essentially point contact between the closure member and the recess allows the surface of the closure member to align accurately with the surface of the housing, thereby minimizing leakage of sound between such surfaces.

Abstract: Method of recognizing pauses in a speech signal when a slowly varying noise signal is superposed on the speech signal. For the purpose of pause recognition so-called short-time mean values connected with a clock pulse are continuously determined from the samples of the disturbed speech signal, which short time mean values are a measure of the average power of approximately 100 ms long sections of the disturbed speech signals. The sequence of these short-time mean values is then smoothed by linear filtration or by means of a median filter. In parallel with the smoothing operation an estimate for the noise signal power averaged over a few seconds is taken from the sequence of short-time mean values. If the smoothed short-time mean value is once or several times less than a threshold which is proportional to the above-mentioned estimate, then it is decided that there is a speech pause.

Abstract: A method and apparatus for use in a digital radio transmission system comprising stationary radio stations arranged in a cellular network and to which are assigned a plurality of mobile radio stations. Transmission of digital messages from a stationary radio station to the mobile radio stations assigned to it is effected by wide-band code division multiplex modulation, and transmission of digital messages from such mobile radio stations to the stationary radio station is effected by narrow-band frequency multiplex modulation. This reduces bandwidth requirements and improves the signal-to-noise ratio for each direction of transmission.

Abstract: Apparatus for reading a disc-shaped record carrier with a light beam. A radial positioning apparatus controls the radial position of the light beam spot on the information track of a record carrier. A lock-in system is provided for switching the radial positioning apparatus into a tracking mode when the light spot is positioned to coincide with the information track. The direction of relative radial movement between the light spot and the information track is detected and a first control signal is supplied to initiate radial tracking of the information track when the relative radial movement between the reading beam and the information track changes from an outward movement of the light spot over the track to an inward movement of the light spot over the track. At the instant the transition occurs, the radial positioning apparatus is enabled to permit the read spot to follow the information track.

Abstract: A radio frequency tuning circuit, for use in a transmitter or receiver, which rejects image frequencies of the frequency band of a supplied RF signal to which it is tuned. The circuit comprises an N-path filter and a feedback loop connecting the output of such filter to the input of an RF amplifier to which the RF signal is applied. The filter includes a tunable local oscillator and a pair of quadrature related signal paths including mixers therein driven by such oscillator, the outputs of such paths being combined by a summing amplifier which produces the output RF signal. The output of the summing amplifier is also supplied to the feedback path, causing the center frequency of the transfer characteristic of the N-path filter to be displaced from the local oscillator frequency. The RF output signal thereby includes substantially only single sideband of the signals produced by the two signal paths.

Abstract: A microwave frequency oscillator capable of being linearly swept over a wide frequency range around a central frequency comprising a field-effect transistor with a high gain, the output of which is fed back to the input from a coupler consisting of two relatively narrow striplines located close together. A wobbulator circuit is fitted in shunt to the feedback network comprises two voltage variable capacitors in series between three line components designed to optimize the frequency modulation linearity in relation to the voltage variable capacitance diode control voltage. The oscillator is useful in equipment requiring extreme linearity such as radio-altimeter sources.

Abstract: An electron image projector for transferring mask patterns onto a semiconductor wafer comprises a patterned photoemissive cathode mask (4) and a target (3) formed by the semiconductor wafer (11) coated with an electron sensitive resist (10). Accelerated by a uniform electric field E and focussed by a uniform magnetic field H a patterned electron beam is projected from the cathode onto the target with unity magnification. The electric field E is established between the cathode and an electron permeable anode grid (2) situated between the cathode and the target. The anode grid comprises a plurality of mutually parallel slats (21,31) spaced apart by elongate electron permeable regions (22,32). The grid may be formed for example by an apertured silicon wafer (see FIG. 2) or conductive sheet, or by metal wires stretched across a metal annulus (see FIG. 3).

Abstract: A composite wire which consists of a number of preferably parallel extending single wire strands bundled to form one solid assembly at least one of which is a bare wire. The composite wire (8) is formed from a bare wire (15) around whch a number, for example, five, or more, single wire strands (9-14) having a thin insulating layer are arranged in the form of a bundle. The assembly is surrounded by a layer of an electrically insulating material, which itself may be surrounded by a layer of a thermoplastic material. The composite wire is particularly suitable for winding saddle-shaped deflection coils for deflection units for cathode ray tubes.