Abstract: The projection screen has a transparent substrate having a front surface which is provided with mutually parallel ribs. Light-absorbing particles 7 whose size is 20 to 75% of the width of the grooves measured halfway the depth of these grooves, are disposed at the bottom of the grooves 4 between the ribs 2. The particles are fixed by means of a glue layer 6.

Abstract: In an FM-stereo receiver the demodulated stereo-difference signal is mixed with a non-sinusoidal signal of the sub-carrier frequency and the mixing product is used to modulate the frequency of an oscillator by means of which the aerial signal is converted to the intermediate frequency range. Interference in the reception is avoided because of the fact that the signal used for modulating the oscillator is free from third and fifth harmonics of the sub-carrier frequency.

Abstract: A television system with enhanced definition in the field scanning direction is presented. In the information transmitter a video signal source is coupled directly and via line delay device with a subtraction circuit followed by a modulator with a subcarrier. An adding circuit is coupled with the output of the modulator and the source, possibly via the delay device. The resultant difference information is transmitted frequency-interleaved with the video information under control of a movement detector, to the information receiver. The receiver contains a filter circuit for separating the information. The modulated subcarrier goes via a demodulator to a superposition circuit to which further the video information is also supplied. The output of the superposition circuit is connected via a line delay device to one input of a switch-over circuit. The video information is supplied to a second input of the switch-over circuit.

Abstract: In an equipment for locating a reflection point in a transmission line a recording is obtained of the impulse response of the path of the echo produced by a transmission signal based on a reference signal x(n) constituted by binary sequences of duration NT which comprise only one bit of non-zero value. At the reception end, the equipment comprises a memory for storing N coefficients Ci which are read cyclically with a view to being modified by successive iterations, each coefficient being modified once per read cycle by the term .alpha..Sgn[e(n)], where Sgn[e(n)] is the sign of the difference between the signal received and the coefficient read at a moment NT and .alpha. is a constant less than 1. The coefficients modified and written into the memory form the values of the desired impulse response.

Abstract: Noise detector for detecting noise pulses in a non-limited radio broadcast signal modulated on a carrier, comprising an amplitude detection circuit and coupled thereto a first signal comparison circuit having a signal input and a threshold input, a first threshold signal depending on the average input level of the noise detector and a second threshold signal depending on the noise pulse repetition frequency being applied to this threshold input. To limit the repetition frequency of the detection output signals of the noise detector without reducing the input sensitivity, the threshold level of the noise detector is controlled in forward direction in dependence on the field strength and the noise pulse repetition frequency.

Abstract: Display device used to display a signal obtained by sampling and stored in a memory and recovered by interpolation points or interpolation vectors and in order to suppress the effect of light fluctuation of the interpolation segments (P) which represent horizontal or somewhat sloping portions of the light trace to be displayed, comprising processing means which, associated with each interpolation segment (P) which have a predetermined energy and are located on one line in one of the fields, for generating at least one and generally two further parallel, so-called anti-flicker segments (I.sub.A) and (I.sub.B) which have a two times weaker energy and are located in the other field, that is to say on one or two lines of the further field which lines enclose the relevant line in the first field.

Abstract: A method of generating color matte signals includes the steps of: inputting hue, saturation, and luminance values; calculating R, G and B color component values from the hue, saturation and luminance values; calculating luminance (Y), and color difference component (Cr and Cb) values from the calculated R, G and B values; and outputting the calculated Y, Cr, and Cb values. The hue value is in two parts, the first of which defines one of six segments formed by dividing each side of the color triangle in half and the second of which define intermediate values within the segment. The R, G and B values are determined by calculating three color components from the saturation, luminance and the second part of the hue value, and assigning the three color components to registers for holding R, G and B values in dependence on the segment defined by the first of the hue value.

Abstract: In order to avoid the occurrence of spurious signals on the output (3) of an electrical circuit (1) when the circuit power supply is switched on and off, the output (3) is disconnected from the remainder of the circuit under the control of a control device (5). The control device comprises a current mirror whose input path (T.sub.1, R.sub.1) is in series with a first resistor (R.sub.3) and whose output path (T.sub.2, R.sub.2) is in series with a capacitor (C.sub.1) between the first (10) and the second (20) power supply terminal. The input and the output path are connected to the bases (12, 14) of two transistors (T.sub.3, T.sub.4) which are connected as a differential pair and whose common emitters are coupled to the positive power supply terminal (10) by means of a second resistor (R.sub.4). After switching on of the power supply the capacitor (C.sub.1) is charged via the current mirror (T.sub.1, R.sub.1 ; T.sub.2, R.sub.2 ), so that the differential-pair transistor (T.sub.

Abstract: An apparatus is described for reproducing digital information from an optically readable disc. In order to measure the phase difference between a channel clock and the intersections of the data signal being read with a decision level, samples on both sides of said intersections are interpolated and the amplitudes of the samples are compared with the decision level. The amplitude difference is a measure of the phase difference.

Abstract: A chroma keying signal generator has an input (1) to which digitally encoded color difference signals (R-Y and B-Y) are applied and output (27) at which a keying signal is produced. The arrangement calculates a value tan.sup.-1 (R-Y)/(B-Y) which represents the hue and a value (R-Y).sup.2 +(B-Y).sup.2 which represents the (saturation).sup.2. Preselected values of hue and (saturation).sup.2 are stored in latches (20,22) and compared with the calculated values derived from the incoming color difference signals in comparators (24,25). When the calculated hue is substantially equal to the value stored in latch (20) and the calculated (saturation).sup.2 is greater than the value stored in latch (21) both comparators (24,25) produce an output which causes the AND gate (26) to produce a keying signal which is applied to output 27.

Abstract: The emitter of an input transistor (T.sub.1) of a Darlington transistor is connected to the base of an output transistor (T.sub.2). The collector of the input transistor (T.sub.1) is connected to the input of a current amplifier circuit comprising a third transistor (T.sub.3) arranged as a diode and having a first resistor (R.sub.1) arranged in its emitter circuit, and a fourth transistor (T.sub.4) having its base is connected to that of the third transistor (T.sub.3) and having a second resistor (R.sub.2) arranged in the emitter circuit. The collector of the fourth transistor (T.sub.4) is connected to the base of the output transistor (T.sub.2). The ratio between the resistance values of the first and the second resistors (R.sub.1, R.sub.2) is larger than the ratio between the emitter areas of the fourth and the third transistor (T.sub.4, T.sub.3). Thus, for small currents a low and for large currents a high current gain is obtained, so that the current gain factor of the output transistor (T.sub.

Abstract: A phase-locked loop is constituted by a controllable oscillator coupled through a phase detection arrangement and a low-pass filter to receive an input carrier applied to a signal input of the phase detection arrangement. In order to decrease the phase synchronization between a carrier locally generated in the loop and an input carrier, an unwanted DC offset generated during phase detection is reduced. The phase detection arrangement has first, second and third cascade-coupled mixer stages. An auxiliary mixing signal is applied from a signal generator to the first and third mixer stages. An input of one of the first and second mixer stages is coupled to the signal input of the phase detection arrangement and an input of the other of the two last-mentioned stages is coupled to an output of the controllable oscillator. The low-pass filter has a cut-off frequency lower than the fundamental frequency of the auxiliary mixing signal, and the fundamental frequency is lower than the frequency of the input carrier.

Abstract: A bipolar transistor R.F. power amplifier in which feedback is used to control simultaneously amplitude and phase distortion. The power amplifier is operated by determining a set of collector supply voltages located at the onset of gain saturation in the bipolar transistor and using feedback to adjust the collector supply voltage in response to variation in input drive level to operate the bipolar transistor in a mode where gain, phase shift and input impedance are simultaneously linearized, found at the onset of gain saturation.

Abstract: A compact-disc-digital-audio player may be adapted to read optical audio discs in which digital information is stored by controlling the time-base correction circuit in this player by means of a clock signal whose frequency is not a constant reference frequency but a frequency which is locked to the time base of the signal being read. As a result of this both the data signal and the subcode will have the same time base without the necessity of modifying the integrate circuits available for the compact-disc digital-audio player.

Abstract: A motorized drawer is moved from a fully closed to a fully open position, or vice versa, in response to user activation of a single pole double throw switch. The motor moving the drawer is connected to the user activated control switch and to a limit switch. Whenever the drawer reaches one of the end positions, a limit switch opens the circuit through which the motor was energized to move the drawer to that position. At the same time, the limit switch partially completes the circuit for energizing the motor in the opposite direction. The latter circuit is completed when the user again activates the control switch, i.e. completes the circuit allowing current flow through the motor in the direction required to drive the drawer to the other end.

Abstract: The base of a transistor constitutes the input of an amplifier arrangement, to which an input signal may be applied. The emitter of this transistor is coupled to the negative power-supply terminal by means of a first resistor. The collector of this transistor is coupled to the input terminal of a first current multiplier circuit, whose output terminal is connected to the output of the amplifier arrangement and to the emitter of the transistor by means of a second resistor. The first current multiplier circuit further has a sum terminal which is connected to the positive power-supply terminal. In order to reduce the distortion in the arrangement it further comprises a second current multiplier circuit whose input terminal is connected to the collector of the transistor and whose sum terminal is connected to the input terminal of the first current multiplier circuit. The output of the second current multiplier circuit is connected to the negative supply terminal of the transistor.

Abstract: The equalizing arrangement in accordance with the invention comprises an equalizing unit (4) for correcting the frequency characteristic of an electric signal applied to its first input (7) under the influence of a control signal (10) applied to its second input (8) and for supplying a corrected electric signal to its output (9), and a frequency analyzing unit (16) having a first input (15) coupled to a point in the signal path between the input terminal (1) and the first input (7) of the equalizing unit (4), a second input (17) coupled to the pick-up means (14) and an output (19) for supplying the control signal (10).The analyzing unit (16) is constructed to apply a Fourier transform to the previously digitized input signals x(t) and y(t) applied to its first and its second input, to compute Fourier-transformed signals F.sub.x (f) and F.sub.y (f) of these two signals and to compute a transfer function between these two signals.

Abstract: The base station comprises a reference carrier generator and a synchronized carrier generator is provided in at least one remote station. Carrier synchronizing information is transmitted from the base station to the remote station and the synchronized carrier and information to be transmitted therewith are transmitted from the remote station to the base station. The base station has a periodically variable phase shifter to an input of which the synchronized carrier is applied, an output being coupled to a phase comparator to which in addition the reference carrier wave is applied. During first periods the phase shifter is subjected to a continuous phase shift. Second periods present in the first period are counted by a counter which is resettable under the control of the first periods. The counter is stopped by the phase comparator when a reference phase is reached during the phase shift. The counting result is numerical carrier synchronizing information, as required for a micro-processor or a micro-computer.

Abstract: The invention relates to a charge-coupled device, in which the reset transistor of the output is clocked--with a positive threshold voltage--by a maximum voltage equal to the supply voltage V.sub.DD. The drain (14) of the reset transistor is adjusted by means of an auxiliary transistor (T.sub.1) controlled by a current source (T.sub.2) and having the same threshold voltage, whose gate (21) is applied to V.sub.DD and whose source (22) is connected to the drain (14) of the reset transistor. Due to the fact that the maximum gate voltage is equal to V.sub.DD, additional voltage sources, such as charge pumps, for generating voltages higher than V.sub.DD are superfluous.

Abstract: An apparatus for generating a pseudo-stereo signal comprises at least two signal channels (3, 4), each signal channel (3) comprising a delay line (7) of which an output is fed back to the input (via g.sub.2). The delay lines (7, 8) have tappings (12, 13 and 14, 15 respectively). The tappings (12, 14 and 13, 15 respectively) are coupled to inputs of two signal-combination units (18 and 19, respectively) whose outputs (20, 21) are coupled to two output terminals (22, 23) to supply the pseudo-stereo signal (FIG. 1).