Abstract: In matrix keyboards whose keys are provided with conductive contacts and are arranged at respective crosspoints of conductors, a diode is connected in series with each key contact in order to allow for n-key rollover, i.e. the simultaneous actuation of several keys in an arbitrary configuration. For many technical realizations of the key contacts, for example in the form of electrically conductive materials provided on plastics foils by silkscreening, the series connection of a diode with each contact element is not simply possible. In accordance with the invention it is proposed to connect an ohmic resistor, which can also be provided by means of a silkscreening process, in series with each key contact and to connect the interrogated matrix conductors to a point of low impedance. Thus, current control is used to a high degree in order to ensure that no signal voltage which is capable of exerting an effect via other actuated keys can appear on the interrogated conductor.

Abstract: An arrangement for generating an angle-modulated carrier signal of a constant amplitude and continuous phase .phi.(t) comprises a control circuit which in response to a given number of consecutive data symbols of symbol frequency 1/T produces addresses at a clock frequency 4q/T, where q is an integer greater than 1, and further produces phase state numbers for characterizing the value modulo-2.pi. or .phi.(t) at the boundaries of the symbol intervals. Connected to the control circuit is a signal processor comprising a read-only memory for storing values representing cos .phi.(t) and sin .phi.(t) at the clock instants, which values are processed after reading to form the analog angle-modulated signal. An arrangement having a comparatively small capacity of the read-only memory is obtained by providing that storage in this read-only memory is only effected for non-decreasing phases .phi.

Abstract: An arrangement for generating an analog angle-modulated carrier signal of a substantially constant amplitude in response to data signals having a symbol rate 1/T comprises a read-only memory for storing modulation parameters, an addressing circuit responsive to a predetermined number of consecutive data symbols for producing read addresses with a rate q/T, where q is an integer greater than 1, and a signal processor for processing read values to form the analog angle-modulated signal.

Abstract: A digital data receiving arrangement, which adapts itself to channel variations of a transmission system, comprises an adaptive receiver stage (11), having an adaptive equalizer and at least one sampler, and producing, at a certain rate, complex samples y.sub.k from the input signal x(t), a decision circuit (14) supplying detected complex samples a.sub.k and an adaptive timing recovery circuit (12) determining the optimal sampling instant by minimizing a quadratic function J which represents the difference between y.sub.k and a.sub.k. The adaptive timing recovery circuit comprises a device (121) for shaping a primary clock signal in accordance with a secondary clock signal, whose period is twice the period of the primary clock and whose consecutive ascending edges are spaced in time by T.sub.1 and T.sub.2, said secondary clock producing alternately two sampling instants .tau. and .tau.+.DELTA..tau.. By minimizing the function J, on the basis of the difference determined for two instants .tau..sub.k and .tau..

Abstract: A circuit for recovering the carrier of an amplitude-and-phase-modulated input signal (in particular QAM signal) is provided with a frequency-controlled oscillator for producing the carrier, with a quadrature detector for supplying signals representing the amplitude of the input signal projected on two quadrature components P and Q of the carrier signal produced by the oscillator and for thus determining the modulation states of the input signal, and with correction means for forming a correction signal for the frequency control of the oscillator on the basis of output signals from a circuit which determines zones in the plane of the quadrature components P and Q. To provide for a satisfactory operation also in the presence of selective fading, the correction means comprises a weighting circuit connected to the zone-determining circuit for producing the correction signal in accordance with distinct weights allocated to the respective zones defined by the zone-determining circuit.

Abstract: A pulse generator for generating pulses having pulse edges at instants at which a varying amplitude input voltage is equal to one of at least two threshold values produced by a voltage source. The pulse generator has at least two voltage comparison circuits each having first and second outputs, first and second inputs for receiving voltages to be compared and third and fourth inputs for receiving blocking voltages applied thereto. The blocking voltages block the transmission of signals to the first and second comparison outputs of each voltage comparison circuit. One of the first or second inputs of each voltage comparison circuit is coupled to the pulse generator, while the other is coupled to the voltage source. The outputs of the voltage comparison circuits are coupled to each other and to the output of the pulse generator by diodes. The diodes connected to the first voltage comparison circuit are biased separately from those connected to the second voltage comparison circuit.

Abstract: Digital tone control arrangement for a digital audio signal, comprising a recursive digital filter whose transfer function contains as many poles as there are zeros, the recursive filter also comprising a recursive portion and a non-recursive portion each receiving filter coefficients which are stored in a memory means. So as to limit the total number of filter coefficients the memory means is divided into a first memory field for storing a first sub-group of filter coefficients and into a number of second memory fields in each of which a second subgroup of filter coefficients is stored. By means of a switching device the first subgroup of the filter coefficients is applied either to the non-recursive portion or to the recursive portion and a selected second subgroup of filter coefficients is applied to that portion (recursive and the non-recursive) to which the first subgroup of filter coefficients is not applied.

Abstract: A pivot mechanism for pivotably mounting a television receiver cabinet on a swivel base includes a molded pivot socket and a molded pivot pin. The pivot socket includes deformable tabs for locking engagement within an aperture in the swivel base. The pivot pin extends through an aperture in the receiver cabinet and includes deformable tabs for locking engagement with the pivot socket.

Abstract: A video game device for use with a conventional television receiver includes microprocessor-based game control circuitry for generating audio and video signals in accordance with a series of digital instructions contained in a removable game cartridge. A signal provided by an RF generator within the game device is modulated by the audio and video signals to produce an RF output signal for application to the television receiver. A switch responsive to the presence of a game cartridge in the game unit supplies electrical power to the game control circuitry independently of power supplied to the RF generator. The switch reacts to disengaging movement of the game cartridge to remove power from the cartridge during such movement to prevent electrical damage to the cartridge and game control circuitry. Current continues to be supplied to the RF generator in the absence of the cartridge to prevent objectionable audio and video noise signals from appearing at the output of the television receiver.

Abstract: A television signal encoder for luminance and chrominance signals presented in digital form comprises luminance and chrominance channels in which the blanking and color burst signals are inserted digitally before the signals are converted to analogue form for modulation and transmission. The luminance signal is presented to a buffer circuit (2) and during the line period the output of the buffer circuit (2) is fed to a DAC (6) via a highway (5) under the control of an enable signal. During the blanking period a ROM (26) applies a digital version of the blanking level to the highway (5). A ROM (3) is enabled for a short period at the start and finish of the blanking period and is arranged as a variable multiplier to determine the slope of the blanking waveform. The output of the DAC (6) is filtered (8) and it is added to the modulated color subcarrier signal and the synchronizing pulse.

Abstract: A television camera has a solid-state pick-up device having pick-up elements arranged in rows and columns, wherein a charge transfer can be effected in the columns by means of control electrodes and an associated control circuit. To have the pick-up device generate a single or multiple interlace picture signal without specific measures being required due to the structure of the pick-up elements, the control circuit supplies during at least one field scanning period out of a number of field periods forming a picture period, a charge transfer signal for effecting a single charge transfer between all the consecutive pick-up elements in each column of pick-up elements.

Abstract: The device comprises a transducer (3) with photoelectric elements (31) and a coupling member (5) which comprises an entrance face (9) which is to be aimed at the document and an exit face (11) which is optically coupled to the transducer. The coupling member (5) comprises a number of light conductors (7) having first ends (13) which are arranged in at least one straight line in the entrance face (9) and second ends (21) which are situated in arbitrary positions in the exit face (11). The relation between the positions of the first ends (13) in the entrance face (9) and the positions of the second ends (21) in the exit face (11) is stored in a memory (29). The photosensitive surface of the transducer (3) may have an arbitrary length/width ratio and the light conductors (7) may extend rather arbitrarily through the coupling member (5) so that the cost of the device may be comparatively low.

Abstract: The clock signal output of an oscillator is synchronized to the frequency of a data signal by detecting the phase difference between the two signals. The control signal signifying the difference is quantized into a number of standard units and a remainder. The remainder is accumulated and, when it is equal to a standard unit, added to the number signal signifying the number of standard units. The frequency of a fixed frequency oscillator is then adjusted in a direction tending to nullify the number signal.

Abstract: A gamma correction factor is applied to a video signal without need of the normally used multiplier by forming the logarithm of the logarithm of the video signal and algebraically adding this signal to a second signal representing the logarithm of the correction factor. The anti-log of the anti-log of the resulting signal constitutes the gamma corrected signal. Analog and digital implementations of the circuitry are illustrated.

Abstract: A clock-controlled filtering arrangement for suppressing a number of interference frequencies related to a clock frequency, which comprises a time-discrete comb filter included in a negative feedback loop for a selective negative feedback of the said interference frequencies, which time-discrete comb filter is connected to an output of a clock generator for controlling the frequency location of the pass ranges of the comb filter. In order to avoid on the one hand the introduction of quantizing noise and the use of additional circuits, such as A/D and D/A converters, and on the other hand the occurrence of error cumulation while maintaining an adequate interference suppression, the time-discrete comb filter is of the switched capacitor N-path filter type.

Abstract: A television receiver of the type capable of displaying standard VHF and UHF televison signals is provided with a single coaxial antenna input terminal. A passive input circuit within the receiver includes two filter sections for separating the VHF and UHF components of a combined VHF-UHF signal applied to the input terminal for application to separate VHF and UHF tuning sections of the receiver. The first filter section, which is located within the UHF tuning section, includes a UHF tuning line for coupling the UHF component to the UHF tuning section. The second filter section, which is located in the VHF filter section, and incorporates elements of the first filter section, enhances the response of the receiver over transition frequencies between the VHF and UHF bands.

Abstract: A line synchronizing circuit for a picture display device comprising a voltage-controlled oscillator for generating a signal whose frequency is higher than the line frequency, a frequency dividing circuit for dividing the frequency of the oscillator signals and a phase comparison stage for generating a control voltage in dependence on the phase deviation between the signals applied thereto, more specifically a received line synchronizing signal and a locally generated reference signal. The elements of the line phase control loop, are part of an integrated circuit which functions as a frequency synthesizing circuit. The reference-frequency dividing circuit incorporated in the integrated circuit is programmed to operate with a constant divisor.

Abstract: An error protection code which acts on subpictures for the transmission of television picture information. First the picture is subpicture-wise transformed (124) by means of transformation functions, for example, Hadamard functions. Of the coefficients thus formed, a number of most significant coefficient bits which are associated with low frequency transformation functions are protected against a bit error (126). Moreover, a comparatively small number of coefficient bits within said number are protected against an additional bit error.

Abstract: A loudspeaker system for converting an n-bit digitized electric signal (11) into an acoustic signal comprises an electrodynamic loudspeaker (1) with n voice-coil sections (4.1, 4.2, . . . 4.n) which cooperate with a magnet system (3). The loudspeaker system further comprises means (18.1, 18.2, . . . 18.n) for short-circuiting a voice-coil section if the value of the bit corresponding to the voice-coil section is such that the relevant voice-coil section is not driven.

Abstract: A digital dynamic range converter of the forward control type for varying the dynamic range of a digital audio signal constituted by a sequence of audio signal samples. Each audio signal sample x(n) is multiplied by a control signal sample s(n) which is delivered by a digital control signal generator. This control signal generator has applied to it unipolar signal samples x(n) which are derived via a transmission channel from the audio signal samples x(n). In order to cause this dynamic range converter to respond rapidly to abrupt variations in the audio signal and to render it moreover universally usable, the control signal generator is provided with a digital peak-value detector which converts the sequence of unipolar signal samples x(n) into a sequence of peak-value samples x(n). The latter are applied to a digital non-linear amplitude transformation circuit which has an adjustable amplitude transmission characteristic curve determined by adjustment quantities R and a.