Abstract: An optical scanning device using one or more rows of scanning spots for simultaneously scanning a plurality of information tracks of an optical record carrier. The resulting radiation produced from the respective spots is imaged on respective photodetectors, and the detection signals from a plurality of the photodetectors are used to derive focus error and tracking error signals for the corresponding scanning spots. Error signals of the same type are then combined to derive servo control signals for respectively controlling focus and tracking of all scanning spots. The focus error signals can also be combined to derive further servo control signals for controlling tilt of the record carrier and tracking angle. Derivation of the servo control signals from error signals corresponding to a plurality of the scanning spots achieves improved immunity against the effects of dust or other artifacts on the surface of the record carrier.

Abstract: A device for automatic sound control includes a detection circuit for supplying objective sound and/or noise measurements relating to an ambient sound volume, and a fuzzy logic control circuit for adjusting, in response to the ambient noise measurements sound transmission characteristics supplied by an acoustic device. The device includes a fuzzy logic conversion circuit which is arranged between the detection circuit and the control circuit and transforms the objective ambient noise measurements into subjective ambient noise measurements for performing said settings. The device can learn the personal settings defined by a listener. The device can also detect speech and perform specific settings.

Abstract: A write amplifier comprising four current mirrors which are turned on two at a time by two switchable floating current sources between the input terminals of the current mirrors in order to produce a write current of alternating polarity through the write head. The parasitic capacitances across the write head and/or the parasitic capacitances of the write amplifier at the write terminals are compensated by means of feed-forward capacitors. The high impedance at the terminals of the write head enables the common-mode voltage across the write head to be fixed at any desired voltage value by means of a common-mode circuit.

Abstract: A record carrier has recorded thereon a data signal which represents data words, added codewords of a first type and added codewords of a second type. The added codewords of the first type have a predefined first relation to the data words, and the added codewords of the second type have a second predefined relation to the data words and the added codewords of the first type. The added codewords of both types enable error correction according to a given algorithm. The data signal is divided into blocks which each contain a control portion (20) which includes control words and a data portion (21) which includes user-supplied data words. The data words and added first and second type codewords are ordered and interrelated so that the order of the data words is not altered by error correction according to the given algorithm, and the second type codewords are located closer to the related control data words than are the first-type codewords.

Abstract: Method and device for binary segmentation of a digital image with a threshold obtained using a histogram to obtain a binary segmented digital image. The digital image is thresholded a number of grey levels, and the number of objects which appear when the digital image is thresholded at each of the grey levels is counted. A histogram of the number of objects per grey level is constructed, and a segmentation threshold is determined automatically on the basis of the histogram. The digital image is then thresholded at the segmentation threshold to obtain the binary segmented digital image.

Abstract: A battery charger whose charging current is shut off on the basis of the temperature difference between the ambient temperature, measured by means of a first sensor (R.sub.A), and the battery temperature, measured by means of a second sensor (R.sub.B). The error in the measurement of the temperature difference, which is caused by the input voltage dependent heat generation by the power supply (PS) in the battery charger, is compensated by a third signal (k*V.sub.i) which is representative of the anticipated additional heat generation as a result of a varying input voltage (V.sub.i).

Abstract: A color image is locally discoloured in the vicinity of edges. The edges extend, for example, between a superposed foreground and a background in a computer-generated image, but also between different regions in natural images which are processed, for example, in a television receiver. Consequently, the edges are perceived as being sharper upon display.

Abstract: In interactive teletext, an individual user establishes a connection (6) with a central computer (14). Requested information is applied to a television transmitter (12) via a teltext inserter (11) and transmitted to the user as personal teletext pages for display on the user's receiver (3). However, other users (4) may be "co-viewers". In accordance with the invention, each personal page is transmitted with a teletext page number P and a sub-code S. Subsequently, a pseudo-page having the same page number P but a different sub-code S' is transmitted. Consequently, the personal page appears on the display screen of the co-viewer's receiver (4) only for a short time.

Abstract: A housing for storing a stack of at least two information discs such as CDs includes a central retaining device for engaging and securely fastening each of the discs. The retaining device consists of a plurality of clamping studs arranged in a circle, and with respective groups of studs being in respective planes, each such plane being for a respective disc. The studs are resilient in the radial direction and those in a given group engage the central opening of the disc to be stored in the relevant plane.

Abstract: A transmission system for encoded transmission of audio signals with frequency band compression. An input signal to be transmitted is divided into two spectral portions in a coder. One spectral portion is digitally encoded by a time-domain coder, and the other spectral portion is coded by a transform domain coder. The two digitally coded signals are then multiplexed for transmission as a composite digitally coded signal to a receiver. At the receiver the composite signal is demultiplexed and the two spectral portions thereof are respectively decoded by a time-domain decoder and a transformer-domain decoder. The decoded signals, covering the respective spectral portions, are then combined to reconstitute the originally transmitted audio signal.

Abstract: A signal processor which includes a first data processing unit for processing data supplied thereto by a data bus system which operates in successive command cycles, and at least one further data processing unit operating in parallel with the first processing unit to process data supplied from the first processing unit during the command cycles. Since the further processing unit does not receive data from the bus system, that processor and still further processors can be added without requiring extension of the bus system. The parallel operation of a plurality of processing units achieves enhanced speed of computation, so that the signal processor is particularly adapted to computation of auto-correlation and cross-correlation functions and for FIR digital filtering.

Abstract: The novel transmission system includes a compression/decompression circuit CVA formed by two processors DSP and .mu.P. The first processor DSP is coupled to a combination analog/digital and digital/analog converter CNA-AN for producing and processing voice signals received from and supplied to the subscriber connected to the accesses to such processor. It is this processor DSP that performs the compression and decompression operations. A second processor .mu.P has receive and transmit accesses for the digital signals grouped in frames. To avoid unacceptable delays in processing of the voice signals, signal compression is given priority over signal decompression.

Abstract: A communication network comprises a transceiver arranged for passing on signals, coming in via an incoming signal path, to an outgoing signal path. The transceiver is coupled by the incoming signal path to a first neighboring transceiver and by the outgoing signal path to another neighboring transceiver. The transceiver comprises an amplifier for amplifying the signals to be passed on. The transceiver is also coupled to a local power supply. The communication network is arranged for supplying remote supply power via the incoming signal path to the transceiver. The transceiver further comprises a coupling device which under normal circumstances is arranged for supplying local supply power from the local power supply to the amplifier and, when the local power supply fails, is arranged for supplying the remote supply power to the amplifier. As a result, the communication between the two neighboring transceivers is not deteriorated by a failure of the local power supply of the transceiver.

Abstract: In multiple-channel microwave transmitters and communications systems, such as multi-point video distribution systems operating at frequencies of around 29 GHz or 40 GHz, good frequency stability for each of the channel frequencies is achieved with a feed-back loop including an error detector circuit. The error detector circuit (39,29) is coupled between a sampler and an input circuit of the source. This detector circuit detects any drift or other error in the carrier frequency of the sample from the desired microwave frequency for that channel signal and provides a corrective signal to the input circuit. The part of the feed-back loop comprising at least a part of the detector circuit is common to a group of the channels. Switch means couple the common part of the feed-back loop between the sampler and the source input circuit of each channel, and so permit this common part to be time multiplexed between the respective feed-back loops of the group of channels.

Abstract: A recording and/or reproducing apparatus for a magnetic record carrier such as a tape or disk. The apparatus includes a magnetic recording/reproducing head, a guide for positioning the face of the head relative to a recording surface of the record carrier, and an actuator for moving the head relative to the guide in a direction normal to the recording surface. The actuator is driven by a control unit which receives a control signal from a detector upon detection thereby of frictional contact between the face of the magnetic head and the recording surface. That causes the control unit to cause the actuator to move the head so as to increase the distance between the face thereof and the recording surface.

Abstract: A television receiver has a subwoofer box situated inside the cabinet of the television receiver. The subwoofer box has a loudspeaker arranged in a chamber and mounted in such a manner that it is situated outside the space enclosed by the subwoofer box. The chamber is dimensioned so as to accommodate the loudspeaker. This enables the volume of the subwoofer box to be optimized in view of the space available inside the cabinet of the television receiver. Moreover, mounting of the loudspeaker and the wiring thereof is simplified considerably.

Abstract: A current integrator for generating an output voltage (Vo) in response to an input current (Ii) to be integrated. The input current is applied to an integration capacitor via a current-current converter. This enables one end of the integration capacitor to be connected to a fixed voltage and to be implemented by means of a MOS transistor which occupies a comparatively small area. A further area reduction is possible by making the current gain (K) of the current-current converter smaller than 1.

Abstract: A dynamic groove bearing (9,89,111) with an inner bearing part (15) and an outer bearing part (17) which is rotatable about the inner bearing part (15). The bearing parts (15,17) are provided with cooperating bearing surfaces (23,35) between which a bearing gap (45) filled with liquid lubricant (75,105) is present. The bearing surface (35) of at least one of the bearing parts (17) is provided with a pattern of grooves (51,53). The bearing surface (35) of the outer bearing part (17) is provided with an annular recess (67, 91,113) which bounds the bearing gap (45). The annular recess (67, 91, 113) is asymmetrical, having at a side thereof facing the bearing gap (45) a first lateral surface (69) adjoining the bearing surface (35) of the outer bearing part (17) and enclosing an obtuse angle .beta..sub.1 with the bearing surface (35) of the outer bearing part (17).

Abstract: An optical heterodyne receiver converts a received modulated optical signal into an electrical IF signal by an IF converter which includes a local laser, a coupling element and an opto-electrical converter. The IF signal is converted into a demodulated signal by a demodulator having a quadratic transfer characteristic. To permit a relatively low intermediate frequency, the IF converter converts the received signal into two quadrature IF signals and in the demodulator two sub-demodulators recover therefrom two demodulated signals which are then combined. This eliminates unwanted quadratic components in the combined signal.

Abstract: An A/D converter has an input part IS which provides differential transitions T1 . . . T.sub.x associated with different levels of an analog input signal. An intermediate part IMS of the converter carries out folding operations and interpolation operations on the transitions to thereby obtain a set of bit-determining signals XO . . . XQ. At least one of the folding and interpolation operations is carried out more than once in alternation with the other of such operations. An output part OS produces a digital output signal from the bit-determining signals. Such an A/D converter can be implemented in a cost-efficient manner and may be combined with digital signal processing circuitry. The repetition of at least one of the operations alternately with the other permits the interpolation factor to be increased without necessitating increased complexity of the output part, and the folding factor to be increased without adversely affecting the accuracy of the converter.