Abstract: An apparatus having a read/write head for reading and/or writing information on an information carrier which may be in the form of a tape or disc. The head is mounted on a drum which is supported on a shaft which axially rotates the drum so as to move the head relative to the information carrier, which in the case of a tape winds around the drum. The drum is supported in the axial direction by a thrust bearing and in the radial direction by fluid bearings (25) and (26). The thrust bearing has adjoining surfaces of which at least one is made of cemented tungsten carbine, the other possibly being of steel. Thus, there is low friction and low wear. During operation of the apparatus the bearing surfaces remain in contact, thereby forming an electrical coupling to a grounding frame of the apparatus so as to limit static charging of the rotating drum.

Abstract: A control unit (75) for controlling a first state variable of a system, for example an angle of rotation .phi. of a throttle valve (7) in a throttle device for use in an internal-combustion engine, the system being influenced by a disturbance variable during operation, for example an oscillating loading torque caused by air-flow fluctuations in the throttle device. The control unit includes a disturbance observer (125) for calculating a value of the disturbance variable at a first point in time on the basis of a mathematical model of the system, and a disturbance predictor (128) for predicting a value of the disturbance variable at a second point in time which follows the first point in time by a predetermined time interval. In this manner, a phase shift between the disturbance variable actually influencing the system and the compensation provided by the system for the disturbance variable is prevented at high frequencies of the disturbance variable.

Abstract: A microwave monolithic integrated circuit includes a coplanar waveguide (CPW) formed by a composite silicon structure constituted by a relatively high resistivity substrate, a first oxide layer on the upper surface thereof, a relatively thin silicon layer formed on the surface of the first oxide layer, and a very thin second oxide layer formed on the surface of the thin silicon layer. The silicon layer and the first oxide layer on which it is formed constitutes a silicon-on-insulator or SOI structure. A metallic signal line and ground planes are bonded to the surface of the second oxide layer. The zone of the thin silicon layer which extends between the ground planes is doped with an active impurity to produce high conductivity therein. As a result, the electric component of a quasi-TEM wave traversing the waveguide is substantially restricted to the thin silicon layer and does not penetrate to the underlying bulk silicon substrate.

Abstract: A switched-mode power supply comprises a transformer (2) having a primary winding (4) connected to a first pair of direct voltage terminals (8, 10) via a switching transistor (6) and having a secondary winding (22) which powers a load (24) via a diode (26). The switched-mode power supply further comprises a second switching transistor (34) which, together with the secondary winding (22), the load (24) the diode (26) and a second pair of direct voltage terminals (38, 40) is configured as a forward converter to power the load from a comparatively low direct voltage (12 V d.c.) supply.

Abstract: A digital transmission system which provides transmission error protection for transmitted data. The input data is encoded using a punctured systematic convolutional trellis code. Row and column components of a matrix formed by the encoded input data are then used to generate a product code in blocks, with trellis closure by addition of redundant data. The data thus encoded is then allocated to quadrature amplitude modulation symbols. At the receiver end the transmitted modulation symbols are decoded by iterative decoding, the reliability of hard decisions being computed so as to provide generation of soft decision output symbols.

Abstract: A hot-air appliance comprises a fan motor connected in series with a heating element to receive a.c. mains voltage. The alternating voltage across the motor is rectified and serves to power additional electronic circuits in the appliance.

Abstract: An RC oscillator having an oscillation frequency which is controllable by supplying a step voltage signal to a series arrangement of a capacitor and a resistor, the oscillation frequency being dependent on the time for the capacitor to be charged to a given voltage level. In order to vary the frequency, the amplitude of the supplied step voltage is varied instead of the resistance of the resistor via which the capacitor is charged. The amplitude variation can be provided, for example, by a potentiometer which acts as a voltage divider for the step voltage. The tolerance of the potentiometer in regard to its resistance value will not be relevant, because it is only the ratio between different portions thereof which is determinative. The step voltage, and consequently the oscillation frequency, will be proportional to the setting of the potentiometer regardless of the resistance tolerance thereof.

Abstract: A power supply control system which prevents thermal overload of the apparatus to which power is being supplied. The supply voltage is controlled so that as the temperature of the apparatus increases beyond a predetermined threshold the supply voltage is reduced in incremental steps, thereby reducing thermal dissipation.

Abstract: An optical disc and an optical disc recording apparatus have an improved protection against undesired or illegal copying. Information on optical discs is arranged in sectors, which each has an address label. The address value of the address labels increases linearly from the start of the disc or from the start of the program area of the disc. The address labels of specific sectors, which may have an informationless content, are given different, e.g zero, address values, which prevent copying CD-ROM discs on a standard CD-Recorder apparatus. Said address labels may be stored in the main data stream or e.g. the subcode channel of a CD system.

Abstract: The invention relates to an electromotive adjustment device with a rotor (9) comprising a magnetized rotary body (8) and with a single-strand, electrically excitable U-shaped stator (11) whose legs (13, 14) form the pole shoes (26, 27) and whose yoke (15) interconnects the two legs (13, 14) and acts as a support for the exciter coil (16), the angular position of the rotor (9) being adjustable by means of the stator current, while the maximum range of the angle of rotation of the rotor is smaller than 180.degree.. Such adjustment devices can be used in particular for the adjustment of a throttle plate in the suction line of an internal combustion engine.

Abstract: A transmission system wherein a plurality of digital signals are coded and the coded signals are used to amplitude modulate respective carrier waves. The amplitude modulated coded signals are then combined for conveyance over a non-linear transmission medium. Due to the transmission non-linearity there will be distortion of the received combined signal, thereby reducing the transmission capacity of the system. In order to increase the transmission capacity, coding of the digital signals is carried out in accordance with a code such that the amplitude of the modulated carrier for digital symbols of higher probability is reduced in relation to the amplitude thereof for digital symbols of lower probability of occurrence.

Abstract: A data storage system having a plurality of parallel magnetic tape tracks. Error protection is based on a frame-wise product code having first code words distributed over a single track and second code words distributed cyclically among all tracks. In a read mode the system drives the tape in a first closed servo loop synchronized by the data rate, and in a write mode in a second open loop operating at a preset tape speed. The tape driver has a bidirectional buffer for framewise buffering data between the tape and an output, while interchangeably presenting either an amble frame (synchronizing patterns) or a data frame to the tape. The system enables handling of data framewise bidirectionally by the tape driver. A third layer of error protection is provided by a Reed-Solomon code operating on a uniform symbol series across a plurality of successive frames without reference to the amble frames, and assignment of all redundant symbols thereby produced to exclusive-redundancy frames.

Abstract: A television signal distribution network includes respective distributor cables for signals from respective satellite antennas, one of such cables also being coupled to a terrestrial signal source and serving as a dual distribution cable for both satellite and terrestrial signals. A switching unit permits each user terminal to be selectively connected to any of the distributor cables for reception of a selected satellite signal. The user terminals are also all coupled to the dual cable via a filter which only passes the terrestrial signal band, whereby the terrestrial signal is distributed to all terminals from only a single cable, independently of the setting of the switching unit. Another of the distributor cables also serves as a return cable for upstream signals from the user terminals. The return path includes a filter which only passes an upstream frequency band below that of the terrestrial and satellite signals.

Abstract: A telecommunication system for transmission along power supply lines of modulated information signals having a selected carrier frequency. The system includes a plurality of communication devices connected along the supply lines, each including a microcontroller and a modem. The modem includes an interface module which establishes a link to the power supply lines for modulated information signals, a transmission module which contains a digital modulator followed a digital/analog converter, and a receiving module. The receiving module includes a digital filter connected between an analog/digital converter and a digital demodulator. The digital filter is adapted to the carrier frequency of modulated information signals present on the power supply lines, whereby the modem can operate at any selected frequency over a broad frequency range.

Abstract: A rear projection screen is described, which comprises an optically transparent plate, a first surface of which is provided with a structure of juxtaposed cylindrical lenses which extend in a first direction and a second, opposite surface intended to be directed towards an audience space is provided with strips of a light-absorbing material. These strips also extend in the first direction. On the second surface the plate comprises diffusing means which are formed by a single element by means of a hologram, which element diffuses the light simultaneously in the first direction at a first angle and in a second direction, perpendicular to the first direction, at a second angle, the first and the second angle being different from each other.

Abstract: A method and apparatus for improved interference rejection, where the rejection is being accomplished by an IIR filter at the transmitter with complementary characteristics to an FIR filter of the receiver, such as a Tomlinson-Harashima transmit-precoder. The improvement is accomplished by providing the ability to preset the transmit and receive filters to the same state, thereby allowing for subsequent receptions to be deterministic. This method and apparatus is particularly useful for correcting for time-varying interference through the use of repeatable, deterministic, training sequences.

Abstract: An electrical actuator for a throttle device has a stator and a rotor, the rotor being coupled to the throttle device and comprising a permanent main magnet. The stator includes in axially extending slots therein auxiliary permanent magnets which interact with the rotor magnet to exert a magnetostatic torque (T.sub.MS) on the rotor which tends to rotate it to a pre-set rest position. The stator also has an energizing coil which when actuated results in an electromagnetic torque (T.sub.EM) on the rotor which is opposed to the magnetostatic torque and causes the rotor to pivot through a limited angle of rotation. The thickness and width of the auxiliary permanent magnets are selected so that the cross-sectional area thereof provides a maximum value of the magnetostatic torque (T.sub.MS) per unit volume thereof, thus minimizing the necessary volume and weight of the auxiliary permanent magnets.

Abstract: The odd harmonic distortion components in the output signal of a capacitively loaded follower transistor is reduced by means of an additional transistor inserted between the emitter of the follower transistor and the bias current source of the follower transistor. A second follower transistor receives the same input signal as the follower transistor and has its emitter coupled to the emitter of the additional transistor via a compensation capacitor. The current through the compensation capacitor is added to the output current and compensates for the odd harmonic distortion.

Abstract: A receiver for use in a synchronous digital communication system wherein transmitted digital signal samples are modulated in accordance with a first constellation of modulated signal values. The receiver includes a phase locked loop for synchronizing digital sampling at the receiver with the received signal samples. The synchronism adjustment error is formed from a pseudo-error function which is a weighted combination of first and second errors, the first error being a function of the distance between received samples and the decisions made with respect thereto in the first constellation, the second error being a function of the distance between received samples and the decisions made with respect thereto in a second simplified constellation derived from the first constellation. A weighting is assigned to the second error which may, in one embodiment, be proportional to the first error.

Abstract: An optical device, such as for example a wavelength division multiplexer/demultiplexer, a wavelength router, an optical comb filter or a planar lens, having a first coupler and a second coupler which are connected by an array of optical waveguide channels. At least one of the couplers is a multimode imaging component (MMI), which has the property that the radiation distribution at any input thereof is imaged onto each of the coupler outputs and with uniform power distribution among the outputs. Efficient power transfer in thereby achieved. Phase differences between the inputs and the outputs are compensated by appropriate differences in optical pathlength of neighboring channels in the array.