Abstract: Testing apparatus in accordance with the invention generates a composite video signal for a CRT which produces a scanning line raster on the video screen thereof clearly displaying the spot size and line focus of the scanning electron beam generating such raster. The display consists of a single scanning test line of high luminance, or white, within an intermediate low luminance or black portion of an otherwise white scanning line raster. The test line is segmented, with black gaps at several discrete locations thereon, each gap being approximately three times the width of the scanning beam spot. Centered within each such gap is a region of high luminance, or white, of a width approximately that of the beam spot. The line focus and spot size of the smallest possible picture element is thereby accurately displayed and so can be measured on the video screen, enabling adjustment of the focussing components for optimum focus.

Abstract: A zero-IF receiver for an FM signal comprises quadrature-mixers (2,3) to which the input signal is applied and which mix the received carrier down to zero frequency. The signals appearing at the mixer outputs (11,12) are fed to a differentiate, multiply and subtract demodulator (22,23,25,27,31) via capacitors (17,19) which block the d.c. components of the signals, thereby preventing amplifier saturation effects, etc. This d.c.-blocking would, unless steps were taken to prevent it, result in distortion of the output signal appearing at an output terminal (32). This distortion is prevented by providing an amplitude divider (33) in the output signal path.

Abstract: The invention relates to a method and system for determining an image of a nuclear magnetization distribution in a body. In known methods, particularly in nuclear spin echo techniques, a resonance signal is generated which has high dynamics. In the method according to the invention dephasing is effected which is non-linear place-dependent or which is frequency-dependent within a spectroscopy distribution, as a result of which the generated resonance signal will have a much smaller amplitude. Since the non-linear dephasing applied within the distribution is known, a correction can be made for this after the determination of the measuring signals.

Abstract: A digital analyzing and synthesizing filter bank in which a digital polyphase network in the analyzing filter bank provides sampling rate reduction by dividing an input signal into M complex sub-band signals, and the sub-band signals are subjected to a further staggered sampling rate reduction of the real and imaginary components thereof. This achieves maximum sampling reduction while permitting aliasing distortions to be compensated in the synthesizing filter bank.

Abstract: The invention relates to an electric arrangement for operating a an electric discharge lamp (13) which is connected in series with a coil (14) and a switch (15) to a pulsatory direct voltage source. The combination of the lamp and the coil is shunted by a rectifier. The lamp is shunted by a capacitor (18) and the switch is periodically rendered conductive at an instant when the instantaneous voltage of the pulsatory direct voltage source is between 0.5 and 0.8 times the then required re-ignition voltage of the lamp. The voltage build up across the capacitor (18) after the switch has become conducting causes the lamp to reignite. The luminous efficacy of the lamp is comparatively high.

Abstract: A storage device for a spare length of an optical line, comprising a flat storage space in which the spare length is wound at a radial distance round a central core and led out by its ends through peripheral openings from which one free end can be withdrawn, accompanied by reduction of the diameter of the turns. The device further comprises lateral guide walls at right angles to the central core and outer peripheral walls to limit the diameter of the turns. To permit the unobstructed withdrawal and sliding back in again of an end of an optical line despite an extremely flat construction, the arrangement is such that the distance between the guide walls (6 to 10 and 11 to 16) is slightly greater than the width of the optical line (1 to 5) and smaller than 1.

Abstract: Base radio stations are spatially arranged in a radio transmission system in accordance with a cellular system, separating the message transmission channels from adjacent base stations being effected either by using the frequency-division multiplex method or by using the code-division multiplex method or by using a combination of these multiplex methods. In appropriately large spatial distances the same set of channels can be repeated in a further radio cell. If a mobile radio station moves during the conversation from one radio cell into another, then it is necessary to hand-over the then existing radio connection. To avoid the necessity of using additional receivers in each base station and to prevent a repeated hand-over in the event of high co-channel interferences, the measurements used for hand-over decision are effected in the mobile radio station.

Abstract: In a semiconductor cathode, the electron-emitting part of a pn junction is provided in the tip of a projecting portion of the semiconductor surface which is situated within an opening in an insulating layer on which an acceleration electrode is disposed. Due to the increased electric field near the tip, a reduction of the work function (Schottky effect) is obtained. As a result, cathodes can be realized in which a material reducing the work function, such as caesium, may be either dispensed with or replaced, if required, by another material, which causes lower work function, but is less volatile. The field strength remains so low that no field emission occurs and serarate cathodes can be driven individually, which is favorable for applications in electron microscopy and electron lithography.

Abstract: A picture signal (PS1) occurring with picture information components at different signal levels in which the signal level differences are greater than the picture information differences at the signal levels is processed with the aid of an amplifier circuit (1-4) to produce a picture signal comprising picture information differences between a minimum and a maximum value. To this end the amplifier circuit comprises two parallel signal channels (1, 2) and (3, 4) and a change-over circuit (2, 4, 5-16) via which one channel for signal processing is operative dependent on the picture signal level, while per channel, for example, a different gain factor (A or B) and a different bias (OV or +Vb) is present for a signal level shift. Change-over is effected by a voltage comparison circuit (5-10, 12-15) which is connected to the output of an amplifier (1) of the amplifier circuit (1-4) and compares the output voltage with a subtantially constant direct voltage.

Abstract: A sample-and-hold circuit arrangement comprising a differential amplifier (5) followed by an inverting amplifier (8). A third amplifier (12) is provided having a capacitor (14) which connects an output of the third amplifier to its input. The inverting amplifier ensures that the voltage on the output (16) of the arrangement is independent of the offset voltage of the differential amplifier (5). Moreover, during a sampling interval the capacitor (14) maintains the voltage on the output (16) at the value which it had in the directly preceding hold interval.

Abstract: A flyback converter comprises a series arrangement of a primary winding (n.sub.1), a transistor switch (S.sub.1) and a resistor (R.sub.1) connected between two input terminals (1, 2) for receiving an input voltage. The series arrangement of a secondary winding (n.sub.2) and a diode (D.sub.1) is arranged between a pair of output terminals (3, 4) for connection to a load (M). The transistor switch (S.sub.1) is controlled by pulses from a pulse-width modulator (10). A sawtooth voltage generated by an oscillator (20) is applied to a first input (11) of the pulse width modulator. A first feedback voltage is applied to a second input (12) of the modulator via a control amplifier (40). This feedback voltage is proportional to the difference between a reference voltage from a reference source (30) and a fraction of the output voltage. A second feedback voltage equal to the voltage across the resistor (R.sub.1) is applied to said second input via a capacitor (C.sub.1).

Abstract: In future broadband-ISDN, with preferably optical fiber subscriber connecting lines, the subscriber can not only access narrow-band ISDN-services but also broadband-services (for example moving picture services). For the integration of low-rate ISDN-signals and high-rate broadband signals, at the transmitter the narrow-band and the broadband signals are additively superimposed on each other with weighting factors depending on their bit rate ratios, to derive a multi-level amplitude sum signal. At the receiver the narrow-band signal is recovered from the multi-level amplitude sum signal by amplitude envelope demodulation, and the broadband signal is recovered by amplitude limiting of such sum signal.

Abstract: The vertical viewing angle of a rear projection screen having a large horizontal viewing angle and good color correction due to the special shape of the light dispersing elements provided on the front side of the plate is increased by elements provided on the rear side and extending in a direction perpendicular to the front side elements. The latter are preferably total internal reflection elements, while the former are not. A bulk diffusor may be largely or completely dispensed with.

Abstract: A picture display device adapted for use in a projection color television receiver and comprising a monochrome display tube provided with a line deflection coil and a field deflection coil arranged contiguously in the direction of the tube axis, the line deflection coil being closer to the display screen of the picture tube. A convergence correction coil system is provided including a first convergence correction coil arranged coaxially with respect to the line deflection coil, one of such coils extending within the other, the first convergence correction coil generating a magnetic field at right angles to that produced by the line deflection coil. A second convergence correction coil is arranged coaxially with respect to the field deflection coil, one of such coils extending within the other, the second convergence correction coil generating a magnetic field at right angles to that produced by the field deflection coil.

Abstract: A cellular digital radio transmission system wherein messages are transmitted from a base station to a plurality of mobile stations assigned to it by time-division multiplexing of time slots in respective TDM time frames, each mobile station being assigned by the base station to a respective time slot constituting a channel for receiving and transmitting information. In order to fully utilize the channel capacity of the TDM time frames for users having different bandwidth requirements the base station divides each TDM time frame into time slots of different durations, whereby a mobile station can be assigned by the base station to a time slot of a duration corresponding to the bandwidth required by such mobile station.

Abstract: A high-frequency heating generator comprising a multi-grid electron tube 15 for use in industrial systems in the range of several kilowatts to a number of megawatts. In order to obtain an economic high-frequency generator, the electron tube 15 comprises at least two grids 152, 153; of which a first grid 153 is connected to a positive feedback circuit (15') of the oscillator circuit. A source of bias voltage may be supplied to the second grid 152. A low voltage control circuit (16) is connected to either the first (153) or second (152) grid, and the anode 151 is connected to a non-controlled d.c. power source (13, 14).

Abstract: A high-frequency heating generator, comprising an electron tube (B) for industrial systems ranging from several kilowatts to a number of megawatts. In similar systems employing an electron tube oscillator a substantial amount of power is dissipated in at least one control element (T) connected in the electron tube cathode circuit at power leads below the maximum power level of the apparatus. To obviate this drawback, an impedance circuit (Z.sub.K) is connected in parallel with the control element (T), which circuit dissipates part of the power to be dissipated in the cathode circuit.

Abstract: An SSB pulse modulator which attenuates unwanted even harmonics of the carrier frequency without expensive filtering. The modulator comprises two pairs of comparators (12, 14 and 16, 18), and the sine and cosine components of the carrier signal are modulating signal [a(t)] and the Hilbert transform [a(t)] thereof are applied to respective ones of the comparators. EX-OR gates (20, 22) multiply together the outputs of each pair of comparators (12, 14 and (16, 18), the multiplied outputs being combined with each other in a signal combining arrangement (24). Each pair of the comparators produces the unwanted even harmonics, which are then attenuated by subtraction from each other in the combining arrangement.

Abstract: An acoustooptic modulator for generating a modulated diffracted beam 14 from a laser beam 10 by refractive Bragg diffraction from a longitudinal compressional acoustic wave directed into a germanium block 21 by a transducer 2.By tilting the end face 26, 30, so that the angle of incidence is 44 degrees, all the acoustic wave energy is reflected as a shear wave S, at 27 degrees, and is then dissipated in layers 24 of lithium or lead on the upper and lower surfaces 19, 22, of the block. The end face 26 is also disposed obliquely in plan angle to further reduce retroreflection.