Abstract: An antenna system capable of receiving electromagnetic radiation having either right or left helical polarization, and either vertical or horizontal linear polarization includes an energy concentrator which concentrates energy at a focal point. A helical antenna is arranged in the proximity of the focal point. A first switch switches the helical antenna to a backfire mode of operation and a second switch switches the helical antenna to an end fire mode of operation. A control mechanism controls the switches to select the nature of the polarization.

Abstract: Memory cards are cheap and contain memory means, but can be forged and duplicated easily. Smart-cards contain also a microprocessor and can be used for cryptographic purposes, but are much more expensive. The plastic support of the card contains randomly distributed ferrite particles (eg. small steel marbles, introduced into the plastic paste during the melting process). This random distribution of the particles is assumed to be impossible to control or influence during the process of fabrication. For personalizing a card, the issuing authority scans the plastic support of the card with a magnetic inductance detector, thereby reading the emplacement of the ferrite particles as a number p. Then the authority computes s=SIG(ID,p), where "SIG" denotes any secure public-key digital signature algorithm and ID the identification details of the card's owner. Finally, s and ID are recorded in the memory means of the card.

Abstract: A shift register for scanning a liquid crystal display includes cascaded stages. A given stage is formed with an input transistor switch that is responsive to an output pulse of a stage upstream in the chain of the cascaded stages. The input transistor switch charges a capacitance associated with a control electrode of a switched pull-up output transistor. The voltage in the capacitance conditions the output transistor for generating an output pulse when subsequently a clock signal occurs to the output transistor. A clamping transistor discharges the capacitance in a manner to prevent further generation of the output pulse when subsequent pulses of the clock signal occur. The clamping transistor is responsive to an output pulse of a stage downstream in the chain. An impedance that is developed at the control electrode is substantially higher after the clamping operation occurs and remain high for most of the vertical interval.

Abstract: In a broadcast receiver, a dc voltage operating source is coupled to an operating voltage terminal of a sound IF integrated circuit via a collector/emitter path of a transistor, and a second source of operating voltage is connected via an RC integrating network to the base of the transistor, with the base of the transistor being connected to ground via a zener diode.

Abstract: The invention presents a method for the fabrication or production of three-dimensional lenses with a variable refractive index by wrapping a material with a given refractive index. It is preferred, that this material has the shape of a thread, which might be cylindrical. The preferred shape of the lens to be produced is spherical or semi-spherical, which can be achieved by an appropiate wrapping process or by cutting the spherical shape. By the inventive method it is possible to produce the said lenses with a smooth varying of the refractive index. It is preferred to use the produced lenses as part of a microwave antenna system.

Abstract: A method of automatically controlling a loop comprising the steps of applying an input signal and an error correction signal to a signal correction circuit to provide a digital corrected signal. Applying the digital corrected signal and a reference signal to an error measurement circuit and providing a difference signal representative of the difference between the corrected signal and the reference signal. Applying the difference signal to a tri-state buffer having an output which is switchable to high impedance and passing the error correction signal to a correction circuit through an integrator and a local generator circuit. The buffer is switched to high impedance when the difference between the error correction signal and the reference signal is zero.

Abstract: Large format TV tubes must produce a high peak brightness in order to be acceptable to the user. This results in a large beam current in bright areas of the picture and in a subsequent defocusing of the resulting spot on the display and in a loss of the sharpness of vertical and horizontal transitions. The apparent sharpness of a vertical transition is gained by modifying the deflection of the TV receiver such that, at vertical transitions, the line on the bright side of the transition is deflected away from the transition region. Advantageously, the amount of vertical scan modulation corresponds to a multi-level control signal and depends on the grey levels of the transition.

Abstract: A method of measuring noise in a television signal includes the steps of storing an estimated noise value N. The activity values A of blocks of pixels are measured and periodically compared with the estimated noise value N. A first correction value C.sub.v1 is added to the estimated value when A>N and a second correction value C.sub.v2 is subtracted from the noise value N when A.ltoreq.N. The second correction value C.sub.v2 is substantially greater than the first correction value C.sub.v1.

Abstract: Extra lines (Yout) for display be progressive scanning are obtained by adaptive interpolation from the original (interlaced) lines. The original lines are left untouched. Each interpolated pixel is the result of a soft switch (456,461,462) between pure interframe interpolation (452), which is the more suitable for areas without moving detail, and interpolation (451) using the Diag-3W algorithm, which is the more suitable for moving areas. The soft switch coefficient (S) is calculated using a normalized comparison between two estimates (E.sub.v,E.sub.t) of the likely error resulting from each of the two kinds of interpolation. To limit the occurrence of wrong decisions due to noise or to certain structures in the picture, the decision is spread horizontally, vertically and temporally, but only over a very small area so that the decision remains local to the pixel (X) being interpolated.

Abstract: The disclosure relates to electrically controlled display devices that use the polarization rotation properties of twisted nematic liquid crystal layers. A display device comprises an optical cavity formed by two polarizers enclosing a layer of twisted nematic liquid crystal with which uniaxial birefringent means are associated in order to compensate for the residual birefringence of the liquid crystal layer which tends to reduce the contrast ratio of the display device. Thus, the homogeneity of the angular distribution of the contrast ratio is improved in relation to a device having no compensating means. The disclosed device can be applied in particular to data display devices for computers and to the display of television pictures directly or by projection.

Abstract: A subscriber/user TV system operates in response to locally stored entitlements. A user gains access to a program only if the description of the program is consistent with entitled rights owned by the user. Each night at a given hour, decoders affiliated with the system tune to a predetermined video or audio channel, a so-called Barker channel. Decoders previously in a stand-by mode are activated in order to tune to the Barker channel. The program provider then sends the entitlement data on the Barker channel while every affiliated decoder is responsive to an incoming data stream.

Abstract: A first transformer is coupled to a deflection yoke and coupled to a derived secondary voltage source for driving a load, for example, for generating an ultor voltage. An on/off switch is responsive to an on/off signal. A second transformer has a primary winding coupled to the switch and coupled to a voltage source and has a secondary winding coupled to the first transformer. A first sampling circuit generates a first feedback signal indicative of current flowing from the secondary winding to the first transformer. A first safety circuit responsive to the first feedback signal controls the effect of the on/off signal on the switch when the current flowing from the secondary winding to the first transformer exceeds a threshold, by limiting the on time of the switch to limit the peak value of the current. A second sampling circuit generates a second feedback signal indicative of the ultor voltage.

Abstract: A television receiver is subject to certain operational conditions which result in poor, unreliable or unusable separated sync pulse signals. During such conditions the use of unsuitable sync signals for synchronization and the like is inhibited to prevent mis-triggering or spurious synchronization. A television receiver contains circuitry for extracting a sync signal, a voltage controlled oscillator (VCO) for generating a scanning signal, and a comparator comparing the scanning signal to the separated sync signal. A microprocessor is used to verify the separate sync signal for invalid or unusable signals and has an output activated during such conditions. The phase comparator has a current output coupled to a integrating capacitor or LPF which develops a varying positive or negative voltage to raise or lower the frequency of the VCO for scanning in phase with the separated sync.

Abstract: A television receiver includes a standby power supply, and an operational or run mode power supply. A microprocessor coupled to the standby power supply controls switching between a run mode, where the standby and run mode power supplies are operative, and a standby mode where only the standby supply is operative. The switching is normally made in response to switch inputs or in response to a signal from a remote controller. The microprocessor is in digital communication with a digital circuit, such as a phase locking tuner, over a bidirectional data bus. The microprocessor is programmed to poll the digital circuit periodically and to monitor the data on the data bus for an expected response to a poll. When the digital circuit fails to respond to the poll, or responds inappropriately, as may occur with lack of adequate power to the digital circuit from the run power supply, the microprocessor automatically switches into the standby mode and disables the run supply.

Abstract: The present invention is a video drive apparatus of the two ramp type which includes facility to selectively adjust the brightness and/or the contrast of an image reproduced on a display device. In this apparatus, at least one of the ramp signals is generated digitally by for example a counter. Provision is made to change the counting rate of such counter which effects a change in display contrast. Provision is also made to selectively change the phase of the ramp signal applied to the second stage relative to the start of respective pulses of the PWM signal thereby effecting brightness changes in the reproduced image.

Abstract: In a television receiver, a source of super sandcastle pulse is connected via a horizontal sync signal extracting first circuit and the vertical sync signal extracting second circuit to the horizontal and vertical sync input terminals of an OSD processor. Advantageously, it has been found that such a super sandcastle pulse provides good and stable relationship between H and V so that flicker and jitter on the screen during OSD do not occur.

Abstract: A television receiver has a switched mode power supply for regulating an output voltage, including a power transformer having a primary winding coupled to an unregulated voltage via a power transistor. The power transistor is controlled by pulses from the output of a controller. In order to sweep the base-emitter charge from the power transistor in order to end collector-emitter conduction, the base of the power transistor is coupled to the output of the pulse generating controller via a capacitor in parallel with at least one diode. During a pulse from the controller, the capacitor is charged to a voltage equal to the forward biased drop across the diode(s). At the end of a pulse at the output of the controller, the voltage across the capacitor provides a negative voltage at the base of the transistor, thus sweeping out the base-emitter charge and sharply turning the transistor off.

Abstract: A VCR or other microcomputer controlled equipment may be subjected to AC supply interruption resulting from many causes, such as, plugging or unplugging the AC supply with the unit switched on, contact bounce on the AC power switch, AC supply drop outs caused by heavy load switching, lightning etc. Short term AC disconnects should not result in the VCR user settings being lost or the user having to manually reset the control system to restore operability. To gain the earliest indication of imminent supply interruption, the AC supply is monitored and a control signal (STOP) is produced that instructs the microcomputer system to save current parameters and assume a low power dissipation mode. With the reappearance of the supply, a RESET signal is generated which enables commencement of the microcomputer system. AC interruptions as short as two cycles are detected and STOP and RESET signals are produced.

Abstract: A television receiver has a switched mode power supply for regulating output voltages including the B+ output to a flyback transformer, by generation of output pulses to a power transformer. A controller for the power supply is coupled in two feedback loops, one responsive to a pulse width modulator coupled to the flyback transformer and the other comparing the output voltage with an internal reference for free running operation. The first feedback loop takes precedence and is active in the run mode of the television receiver. In the standby mode when horizontal rate pulses are absent, the second feedback loop takes over. The second feedback loop has a different reference level than the first, such that when switching from the run mode to the standby mode a transition interval occurs in which no pulses are output by the controller, thereby causing the B+ voltage to the flyback transformer to fall.

Abstract: A muting circuit for eliminating transient signals generated due to power supply "turn-on" and "turn-off" is presented. In one embodiment, a junction in a signal chain is AC shunted to ground independent of the DC status of the junction. This shunting is in response to a signal generated by a power supply controlling microprocessor when the microprocessor energizes or de-energizes the power supply for a portion of the signal chain coupling signal to the acted upon junction. In another embodiment, the junction is AC coupled to ground during turn-on through a diode in series with a capacitor with the diode first being forward biased and then reverse biased to remove the AC shunt. The biassing of the diode is accomplished by application of two different sources of voltage to respective electrodes of the diode.