Abstract: A peak detector comprises a device for storing a value representing the currently detected peak amplitude (Cp,Cn), a circuit for detecting whether the input signal amplitude exceeds the stored value (D1 to D4), an apparatus for updating the stored value at a fast rate if the input signal amplitude exceeds the stored value by more than a given value (D1/V1, D3/V4), and an apparatus for updating the stored value at a slow rate if the input signal amplitude exceeds the stored value by less than the given value (D2/R2, D3/R3). Analogue and digital versions are described together with their application to data slicers in, for example, teletext decoders.

Abstract: A circuit includes a generator that supplies a signal that is directly proportional to the absolute temperature. No calibration or external reference components are necessary.

Abstract: The field-display means of a conventional television set are used, to which the odd lines of a VGA image are transmitted during one field and the even lines during the next field, thereby providing for the use of a television set as a computer monitor.

Abstract: A post-processing method and apparatus to produce focus/defocus effects in computer generated images of three dimensional objects. A convolution filter stores pixel values (V) and associated depth values (Z) with a filter kernel being selected from a look-up table in dependence of the depth of the centre pixel (Z.sub.c) in relation to a specified focus depth (P). To minimize spurious effects where filter kernels overlap objects at different depths in the image, an inhibition function stage varies the amount by which each pixel contributes to the kernel in dependence on that pixel's depth value (Z) and the centre pixel and focus depth values (Z.sub.c and P). Inhibition profiles over a range of contributing and centre pixel values are provided.

Abstract: A magnetic cassette recorder comprises a magnetic head 19 which can be translated in directions 21 and 23 between an operating position, in which the head cooperates with a magnetic tape in an inserted cassette 3, and a withdrawn position, in which the head is clear of an inserted cassette. In the withdrawn position the head can be pivoted about a pivotal axis 25 between a first angular position and a second angular position. The head is electrically connected to stationary parts of the recorder by means of a flat flexible multiple electrical conductor 27, such as a foil carrying printed electrical conductor tracks or a flat cable. The conductor is arranged as a cylindrical spiral about the pivotal axis 25 and its end 55 which is remote from the head is connected directly to stationary parts of the recorder, so that translations of the head in the axial direction result in the spiral being extended/compressed and pivotal movements of the head result in the spiral being coiled/uncoiled.

Abstract: To be able to transmit television pictures in a digital form through a medium having a limited bandwidth, the pictures are subjected to picture transform and to variable-length coding. The picture to be transmitted is converted in this manner into a bit stream comprising code words of variable length. This bit stream is converted into a channel bit stream which is less sensitive to transmission errors. To this end the most significant code words (representing the average luminance and the coarse picture details) of sub-pictures of 8*8 pixels are accommodated at fixed bit positions of the channel bit stream. These code words can be retrieved by simple count-down of the bit positions. The other code words are distributed over the other bit positions. The decoder is relatively simple because the length of each block comprising significant code words is also transmitted. This length is preferably adapted to the extent of picture detail in the sub-picture.

Abstract: A magnetic-tape-cassette apparatus provides a pulley (1, 21, 22) for a belt drive, particularly to a flywheel for a deck of the magnetic-tape-cassette apparatus. The pulley has a groove (10) at its circumferential edge (6, 7), in which groove a drive belt (11, 27) is engageable to drive the pulley. In order to manufacture such a pulley simply and cheaply, the pulley comprises a central disc (2) and a first (3) and a second (4) end disc. The first and the second end disc are shaped along their circumferences in such a manner that they form the groove in which the drive belt is engageable.

Abstract: The invention relates to a system for reading magnetic information, comprising at least one read head H0 provided with two magnetoresistive rods (MR10, MR20) whose electrical resistivities (RMR10, RMR20) vary in mutually opposite senses when they are subjected to a same variation in magnetic field. According to the invention, the reading system comprises a detection module DET which comprises two resistors R of substantially the same resistance value, an amplifier A having one input and one output, and a comparator Cp having two inputs and one output. Each resistor R has a terminal connected to the output terminal (M10, M20) of one of the magnetoresistive rods, while the other terminals of the resistors are interconnected so as to form a common junction point NC. The voltage of the common junction point NC is amplified and compared with a reference voltage Vref by the comparator Cp.

Abstract: The invention relates to a loading mechanism in a tape deck of a magnetic-tape-cassette apparatus, for moving a magnetic-tape cassette from an eject position of the loading mechanism into a play position of the loading mechanism. The mechanism comprises a cassette holder for holding the magnetic-tape cassette and a first lift plate, by means of which the cassette holder is movable between an intermediate position of the loading mechanism and the play position of the loading mechanism substantially in a vertical loading direction. The first lift plate and the cassette holder are movable from the eject position into the intermediate position in a horizontal loading direction, and a lift element is arranged on a frame so as to be rotatable and so as to be movable in the horizontal loading direction. The cassette holder, the lift element and the first lift plate are movable from the intermediate position into the eject position and vice versa in the horizontal loading direction.

Abstract: A digital information signal is channel encoded into a channel signal. Data sequences in the channel encoded information signal that give rise to an analog signal, upon reproduction or reception, with a single frequency component at f.sub.b M, are limited in length. M being an integer constant larger than 2 and f.sub.b being the bit frequency in the channel encoded information signal.

Abstract: To detect a watermark signal embedded within an information signal, predictive filtering is applied to either the information signal, a plurality of applied watermark signals, or both types of signals. After the filtering, a correlation is determined between the information signal and the watermark signals. The amount of the correlation is indicative of whether a particular watermark is embedded within the information signal.

Abstract: A combination of a support for a disc-shaped recording medium and a holder for the support. The support is a box-shaped cartridge having two parallel rigid main walls. The main walls have facing inner surfaces which bound a space for receiving the recording medium. At least one of the main walls has a window to provide optical access to the recording medium. The holder includes a wall portion for covering the window in a holding position of the cartridge on the holder.

Abstract: A slow Phase Locked Loop (PLL) is utilized to prevent an abrupt change to a video display containing multiple images, when the source of the synchronization is changed. Such displays include Picture in Picture (PIP) television systems and computer displays. By appropriate buffering and memory management, visual disruptions can be minimized by slowly synchronizing the display synchronization signals to the new synchronization source. The slow synchronization also produces a less disruptive visual image when the source, or channel, of a single image display is changed, and allows for smooth visual transitions on displays having inertial elements, such as color wheels.

Abstract: A method and an apparatus are disclosed for recording a binary signal onto a magnetic record carrier. The binary signal is supplied to an input terminal. The apparatus comprise generators for generating at least two write pulses (P.sub.1,P.sub.2) for each bit of the binary signal to be written. More specifically, the generators are adapted to(i) generate at least two write pulses of a third polarity for the first bit of the first polarity in the first sequence,(ii) generating a write pulse of the third polarity and a write pulse of a fourth polarity for the at least second bit of the first polarity occurring in the first sequence, the third polarity being opposite to the fourth polarity,(iii) generating at least two write pulses of the fourth polarity for the first bit of the second polarity in the second sequence,(iv) generating a write pulse of the third polarity and a write pulse of the fourth polarity for the at least second bit of the second polarity occurring in the second sequence.

Abstract: A circuit arrangement for controlling the operation of a d.c. motor. The circuit includes a controller having a reference potential input and a control input. The control input is used for controlling the speed of the motor. A plurality of switches allows the circuit arrangement to enable the controller to control the motor when the motor is to operate in one direction. The plurality of switches further causes the controller to be unable to control the motor when the motor is to be operated in a second direction. This arrangement improves speed control accuracy.

Abstract: The invention relates to a system for reading magnetic information, comprising a magnetoresistive bar and a first differential amplifier connected to the magnetoresistive bar. A reading system according to the invention also comprises a second differential amplifier arranged in parallel with the first amplifier, a first capacitor arranged between the first transistor and the magnetoresistive bar, and a second capacitor arranged between the fourth transistor and the bar, and an analog adder combining the output signals of the first and second amplifiers. This structure allows integration of the decoupling capacitors and thus prevents the occurrence of external resistances and inductances which are detrimental to the common-mode reject rate.

Abstract: An interface between two clock domains transfers data between the two clock domains without corruption or loss of data being transferred. Each clock domain has a respective clock. The two clocks have a fixed relationship. A data signal is registered in a plurality of registers in the first clock domain, the number of which is related to the fixed relationship of the clocks. Each register outputs a specific output signal, one of which is selected by a multiplexer in the second clock domain, to be output to an output register. The output register then outputs the data in synchronism with the second clock.

Abstract: In a security system, detector apparatuses (101, 102, 103) transmit an alarm message to a central apparatus 100 via RF in response to detecting an alarm condition. The message comprises a source identification uniquely identifying the transmitting apparatus. The central apparatus 100 raises an alarm if the alarm message is sent by a detector apparatus, which is part of the system. To this end, the central apparatus 100 only processes an alarm message if the source identification of the alarm message is stored in a memory means 200 of the central apparatus. For a new detector apparatus to be accepted as part of the system, the identification of the detector apparatus needs to be stored in the memory means 200 of the central apparatus. To reduce the chance of identifications of neighboring apparatuses inadvertently being stored, a detector apparatus transmits a learn-detector message in response to a learn trigger, for instance from a user.

Abstract: An amplifier and a method for detecting the presence of a load (3) in a bridge-type amplifier configuration, in which the amplifier includes two amplifying circuits (1, 2). A load detection sequence is combined with an activation sequence of the amplifier by providing, during activation of the first amplifying circuit (1), a low impedance (4) at the output (203) of the second amplifying circuit (2), and determining whether a current flows through the low impedance (4) or one of the outputs (103, 203) of the amplifying circuits (1, 2) during the activation of the first amplifying circuit (1).