Abstract: During the decoding of channel symbols included in multi-symbol code words in a data stream which is protected by a multi-symbol error correcting code such as a Reed-Solomon code, all channel symbols are first demodulated to derive the corresponding code symbols and a first indicator flag indicates whether or not the demodulation is reliable. All code symbols of a code word are subsequently collected, after which decoding is commenced to decode such code symbols and if correction of incorrect symbols of a code word is possible the code word is corrected. The decoding reliability of the corrected code word is indicated by a second indicator flag. If the corrected code word is unreliable, the stream of channel symbols is addressed again. During the latter operation, only the unreliably demodulated code symbols are replaced by new code symbols in order to enable renewed decoding of the code word.

Abstract: Control circuit for memory type matrix display with k columns and r rows for k times r display elements, wherein each display element can have one of 2.sup.m brightness levels. This control circuit has a video memory for storing brightness information for the display element of each column. It comprises a column memory for each column. Each column memory including m column shift registers. Each column shift register having an input coupled to a corresponding information input for that column, and an output. A line time shift signal C.sub.s being applied to the shift pulse input of all column shift registers for shifting all column shift registers substantially at the end of each line time. The m output bits thus obtained are sequenced by means of a controlled gate circuit to produce a sequence of output bits at the information output of that column. This gate circuit is controlled such that each output bit lasts a predetermined part of the subsequent video line time.

Abstract: A picture pick-up or display device, respectively for recording a scene or displaying a scene image, respectively with the aid of a line raster formed by a plurality of horizontal lines which are consecutively scanned in opposite directions. The device comprises a line deflection circuit in which the line deflection coil forms part of a resonant circuit whose tuning frequency is substantially equal to half the line frequency, as a result of which the power dissipation is kept low. By means of a control circuit it is ensured that corresponding points of scanned lines are accurately in line in the vertical direction, the control circuit being arranged for causing a zero-crossing of the line deflection current and a signal which is characteristic of half the video information of a line substantially to coincide. The control circuit comprises an analogue delay element for setting the time position of this signal.

Abstract: A method by which substations in a multiple access communication system, such as a mobile radio system, may access the base station. Access is determined by the base station in accordance with any of a plurality of operating modes during successive message time frames, the particular mode being determined by the base station from an estimate of prevailing traffic conditions. The selected operating mode during any frame is signified by a code and parameters transmitted by the base station in an Aloha invitation message which establishes such mode and the dynamic operation of the substations in that mode. The operating modes include a light traffic mode, a dynamic frame-length mode, a hybrid mode in which subsets of the population of the substations are formed, and a polling mode.

Abstract: Television system in which the digital data, the chrominance signals and the luminance signals are time-division multiplexed. This system, adapted for transmitting pictures having an aspect ratio of approximately 5/3, is such that the compatibility with receivers capable of receiving and processing the signal in accordance with the MAC system with an aspect ratio of 4/3 is ensured without any change in the instantaneous digital flow rate, nor in the compression factor of the video signals. In addition, the horizontal extension of the picture to the aspect ratio 5/3 is obtained by reducing the length of the data burst preceding the video signals and by suppressing a certain number of video lines located at top and/or at bottom of the picture, in order to make it possible to place the data suppression in the bursts in the position of these video lines and within a certain number of previously non-utilized line periods during the field retrace.

Abstract: In a circuit arrangement for synchronization of the phase of a frequency-divided signal with an edge of finite slope of an essentially periodic synchronizing signal with an oscillator supplying a clock signal, a frequency divider which generates the frequency-divided signal and a phase detector which comprises a first comparator for coarse phase detection, a second comparator for fine phase detection and a selector circuit which derives a resulting phase signal applied to the oscillator to control the frequency of the clock signal and originating from the first comparator in the case of large phase variations and from the second comparator in the case of small phase variations, precise adjustment to the edge is nevertheless achieved in the case of an amplitude-discrete synchronizing signal with limited time resolution because of the fact that the synchronizing signal is applied to the phase detector as a sequence of amplitude-discrete values which is formed by sampling the synchronizing signal with the clock

Abstract: A television transmitter comprises a video signal input (1) feeding a modulator (2), a pre-corrector (3), an up converter (4) and power amplification stages (5,6). The stage (6), typically a Klystron amplifier, is operated in a non-linear mode to increase efficiency and the pre-corrector (3) is provided to provide a correction for the output amplifier stage non-linearity. A portion of the output signal is coupled to a demodulator (8) whose output is fed to measurement means (9). The measurement means (8) measures the distortion of the output, for example non-linearity, differential gain, etc., and applies a signal to a computer (11) via an interface circuit (10). The computer then calculates control signals which are applied through the interface circuit (10) to the pre-corrector (3). The control signals are effective to vary the transfer characteristic of the pre-corrector circuit (3) in such a manner as to reduce the output distortion to a minimum value.

Abstract: A television transmission system capable of transmitting and receiving a high-resolution television signal having a wider than standard aspect ratio, which high-resolution television signal is, in part, compatible with standard television receivers. In an NTSC format, the high-resolution television signal has an active bandwidth of 14.0 MHz and includes picture frames having 657 scanning lines and a 51/3:3 aspect ratio. This high-resolution television signal is converted into two transmission signals, a first of which being compatible with standard television receivers and including a center low-frequency portion of said high-resolution television picture frame, the number of lines therein having been converted to 525 lines, and a second of which including the remaining information in said high-resolution television signal.

Abstract: The fading circuit comprises first and second video signal inputs (1,12) for receiving 8 bit parallel digitally encoded video signals and first and second fading control signal inputs (5,16) for receiving 8 bit parallel fading control signals. First and second multipliers (4,15) multiply the video signals by the fading control signals. The outputs of the multipliers (4,15) are truncated to 9 bits and fed to first and second inputs of an adding arrangement (11). A dither signal is fed from a dither signal generator (22) to the carry input (24) of the adding arrangement (11). The output of the adding arrangement (11) is fed to a ROM (28) which is programmed to add 1/256th of the output of the adding arrangement (11) to the output of the adding arrangement (11) and produce an 8 bit output which is applied to the output (31) of the fading circuit.

Abstract: Digital integrated C-MOS circuit in which two cross-coupled P-MOS transistors are connected by two separation transistors (N-MOS) to two complementary switching N-MOS transistor logic networks. The gate electrodes of the separation transistor are connected to a reference voltage source. The switching speed of the C-MOS circuit is increased in that (a) the voltage sweep across the logic networks is reduced; (b) each P-MOS transistor, which is connected by a separation transistor to a junction of the logic network to be charged, is slightly conducting and so is "ready" to charge such junction, and (c) the separation transistor between the fully conducting P-MOS transistor and the junction to be discharged in the second logic network constitutes a high impedance which prevents the conducting P-MOS transistor from charging that junction.

Abstract: A wide-band frequency modulated DBS signal of the type having time sequential compressed chrominance and luminance (video) components is received by an aerial (1), frequency converted in a down converter (2) and applied to the input (4) of a conversion unit. The conversion unit has a tuner (5), i.f. stage (9,10) and a frequency demodulator (11) to produce baseband video which is applied after de-emphasis at (12) to a modulator (27) where the video is amplitude modulate onto a vision carrier from an oscillator (28). The modulated carrier is applied through a vestigial sideband filter (29) and an adder (30) to an output (31). Sound/data bursts present in the DBS signal are recovered in a stage (13) and processed in a processor (14) where the sound/data bursts are expanded to occupy approximately a line period at a bit rate which is an integral sub-multiple of the bit rate for the sound/data bursts in the received DBS signal.

Abstract: In an encoding circuit for the S.E.C.A.M. color television standard a signal value is added to each one of two line-sequential color difference signals to determine the quiescent frequencies. The modulating signal containing the color difference signals is subjected to double sided amplitude limitation. The ratio of the level difference between the limitation limits to the difference between the added signal values is substantially constant. The signal path for the modulating signal to the FM-oscillator comprises a controllable amplifier, limitation being effected first followed by amplification.

Abstract: The circuit arrangement in a communication system which is protected by subscriber-specific passwords having a memory which contains all the possible passwords and a comparator which compares each received password with the memory content. A monostable delay circuit with a subsequent logic combining gate, are connected to the output of the comparator (2) via an input gate (5). The monostable delay circuit and the logic combining gate are such that in the presence of an energizing signal applied to a special input (C), when there is non-agreement between the received and the stored passwords the monostable delay circuit starts and during operation inhibits the logic combining gate, while when there is agreement the logic output gate (6) is enabled. Such a circuit arrangement can be provided before each selector stage of a switching system of before each accessible channel of a mobile radio system.

Abstract: A method of encoding a recording signal which includes a composite color video signal and a digital audio signal, for recording the same on and reading it from an optical video disc is disclosed. The color video signal is frequency-modulated on a carrier wave in the customary manner, while the audio signal pulse-width modulates the carrier wave.

Abstract: System for the secret transmission of audio signals having at one end a coding arrangement comprising an input low-pass filter which selects the secret audio signals to be transmitted, two parallel signal paths at the output of this filter, each path having a modulator of the phase-inverting type and a further low-pass filter, a stage for generating two modulation signals of the frequencies F.sub.1 and F.sub.2 and a first change-over switch which alternately switches through the output of the two paths in dependence of the state of a binary quasi-random signal, the encoded audio signals to be transmitted being available at the output of the change-over switch, and in which at the other end there is a decoding arrangement comprising a stage for regenerating the modulation signals of the said frequencies F.sub.1 and F.sub.

Abstract: The generator comprises a ferromagnetic core (1) having a primary winding (3) and a secondary winding which comprises a number of concentric secondary coils (7A-7F), which are wound with the same winding senses and have substantially the same number of turns and are provided with a layer of insulating material (9A-9E) between every two consecutive coils. The high-voltage portion of the generator is formed by a number of sections (19A, 19B, 19C), each of which comprises at least two series-arranged secondary coils (7A-7F), the number of secondary coils being equal for all sections and the last coil of each section being arranged in series with a rectifier (13A, 13B, 13C). All sections are arranged in series such that the rectifiers have the same forward directions.

Abstract: A video signal processing arrangement comprises an input (1) for receiving an input video signal and output (2) at which the processed signal is produced. The arrangement includes a vertical filter (3), a horizontal filter (4), a vertical interpolator (5) a horizontal interpolator (6), a field store (7) and a control circuit (8). The control circuit (8) produces control signals which are fed via paths (20,21,22) to the vertical and horizontal interpolators (5,6) and the field store (7) to re-configure their positions in the signal processing chain in dependence on whether the television picture represented by the input video signal is to be squeezed or zoomed.

Abstract: A stand-alone functional apparatus comprises a plurality of processing circuits which operate under the control of status data applied by a control circuit and possibly apply status data to the control circuit, more specifically a television receiver with the control circuit in the form of a microcomputer. To protect this microcomputer against external disturbance, a plurality of addressable nonvolatile memory locations are present in which auxiliary status data for at least one processing circuit are stored. A program store comprises a plurality of control programs and also a recovery program. The latter is made operative in response to a disturbance, causing the auxiliary status data to be applied to the relevant processing circuit(s). To enable the determination of a disturbance at least one of the control programs includes a check program.

Abstract: A head-end for a signal distribution system with selection facility, includes a matrix (8) and a multiplexer (12) connected thereto for forming a multiplex signal. The head-end further comprises A/D converters (4-1 to .DELTA.-N) for converting the wide-band input signals into digital signals prior to supply to the matrix. The multiplexer comprises two amplitude modulators (13, 14) for the mutual quadrature amplitude modulation of a carrier (17) by two digital signals, and a summing means (18) for adding a digital signal in the base band to the modulated signal. A signal receiver for one of the modulated signals comprises a synchronous amplitude demodulator (21) connected to a synchronized carrier source (20) and also comprises means for digital-to-analog conversion (24).

Abstract: A circuit for signal processing in a picture display device, comprising a line signal and audio signal processing stages which form part of an integrated circuit. A uni-directionally current-conducting element is provided between a supply terminal of the line signal processing stage and a signal terminal of the audio signal processing stage and a further uni-directionally current-conducting element is provided between the supply terminal of the line signal processing stage and a supply terminal of the audio signal processing stage. The elements are not simultaneously conductive. The signal terminal of the audio signal processing stage can either be a supply terminal for the line signal processing stage or a volume terminal for the audio signal processing stage.