Abstract: A process and arrangement for tracking and eliminating disturbances which occur in particular while scanning optical information carriers. The invention avoids the inconvenience of disturbance elimination using time-delayed auxiliary beam signals by influencing the auxiliary beams of a scanner working according to a three-beam principle in such a way that they hit the information carrier to be scanned as two auxiliary beams which lie next to each other on the track radius, so that disturbances due to subtraction between the auxiliary light spot signals formed by the auxiliary light spots are eliminated. A birefringent crystal is preferably used in order to direct the auxiliary beams in this manner. The invention is preferably suitable for optical information carrier scanning devices.

Abstract: When digital data are being transmitted, parts of these data can be irreversibly destroyed by channel interference. Gaps produced in this way in the bit stream must be indicated and the respective decoder must be resynchronized. When encoding in accordance with the MPEG2 standard is used, the timing of this resynchronization is heavily dependent on the contents of the bit stream elements which have been lost. Thus, in the event of failure of the picture start codes or extension start codes of the frame layer which are important for the decoding, although the decoder will resynchronize to the slice-start code of the following slice layer, important information such as the time reference of the frame, for example, the frame type (I-, P-, B-frame) or else important parameters relating to the decoding of movement vectors may be false in this case, however.

Abstract: A back-projector projection system, which includes a projector which emits a light beam, a screen and means for directing the light beam onto the screen. The means for directing the light beam onto the screen includes a first means which circularly polarizes, in a first sense, the light beam output by the projector, at least one polarization filter which reflects light circularly polarized in a second sense opposite to the first sense, and a plane mirror. The polarization filter and the plane mirror are positioned substantially parallel to each other to make the light beam output by the first means undergo three reflections, between the polarization filter and the plane mirror, before directing the beam onto the screen.

Abstract: The object of the invention is a demultiplexing device.This device is characterized in that it comprises means for storing data of a multiplexed data stream (4), programmable means for storing data filters (8), comparison means (19) between the data of the multiplexed data stream and the data filters, and means (12) for transferring data of the multiplexed data stream to storage means (5) in relation to the comparisons made.The invention has a particular application in the field of digital television reception.

Abstract: A method for digitizing intermediate frequency (IF) video signals, of acceptable cost, in which the signal from a tuning device is pre-filtered and amplified. This pre-processed signal is fed to a sample and hold circuit whose bandwidth covers the range up to at least the maximum intermediate frequency, and the sampled signals output from the sample and hold circuit are fed to an analog-to-digital converter whose dynamic resolution is sufficient only up to about half of the sampling frequency. The invention is applicable to the processing of digital IF video signals.

Abstract: The present invention can be used to make integrated circuits on the same substrate as the active matrix owing to the possibility that it offers of connecting transistor gates to sources or drains of the same or other transistors, and thus be used in a "integrated drivers" technology. It is also possible to make different types of transistors and capacitances using this method, without adding any additional mask levels.

Abstract: Machine for recording and playing back information with a tape-storage medium comprising a tape-counting device for determining locations on the storage medium representing a beginning, an end or a section of a recorded information and labeling the locations as data. The labeled locations are stored in memory and marked. Selective winding to a chosen recording section which is associated with one of the marks occurs by means of the tape-counting device and the stored labeled data, together with another one of the marks which is detected and used as a reference, wherein, due to the detection of this reference mark, the tape-counting device is set to the data which was determined with the setting of the reference mark, and wherein the mark associated with the chosen recording section is dependent on the data of this reference mark. A tolerance window arranged symmetrically with respect to the reference mark is included to assist in the detection of the reference mark.

Abstract: A method and apparatus for the transmission of digital signals comprises the steps of forming at least two data channels carrying data packets, and eventually header data. The channels have different levels of error protection and include picture data, wherein the data packets within one of the channels have the same level of error protection, and wherein a super-ordinate channel has a higher error protection than a subordinate channel. Important information of a subordinate channel is then transmitted in a super-ordinate channel. The important information allows following erroneous reception of the digital signals an improved recovery of picture data decoding.

Abstract: A lens having a variable index of refraction and a point of symmetry is fabricated from a plurality of substantially identically shaped parts. Each of the parts is pyramidal in configuration and has a base and a plurality of sides extending from the base to an apex. Each of the parts has a coefficient of refraction which varies from the base to the apex.

Abstract: A high performance single light valve color projection system that enables sequential display of color, and an addressing process for this system. Several rotating glass plates are sequentially inserted between the light valve and the objective. These glass plates create a spatial offset of the image of light valve pixels three times per frame on the projection screen. The sets of plates are rotated by a motor with an axis parallel to the optical axis of the motor, and intersect the image beam at each image frame.

Abstract: For interference-free transmission of high-frequency signals, the receiver must be terminated with the characteristic impedance of the transmission line. This can be achieved by a single base-connection circuit, but in this case the input impedance is dependent on the current flow and is therefore not exactly constant. Adding a second base-connection circuit makes the circuit symmetrical, so that opposite effects are canceled, which makes the input impedance constant. Production in both bipolar technology and in MOS technology is possible.

Abstract: A multi beam track system and method is used for the retrieving of information stored in optical memories like optical disks. The information carrying beams reflected on the surface of such a optical disk results in spots on the surface of a detector array. Because these beams are very close to each other, the resulting spots tend to overlap so that cross talk conditions between neighboring channels occur. As result the S/N ratio becomes worse. According to the present invention a plurality of laser beams arranged in a row is used, where the laser beams are linear polarized and the polarization of neighboring beams differ by 90.o slashed., i.e. neighboring laser beams have perpendicular linear polarization. After reflection on the surface of the optical disk the row of reflected laser beams is separated into two rows by an separating means which is polarization dependent so that beams are separated in space according to the polarization.

Abstract: Block matching is well known as a robust and intuitively simple method of motion estimation for television pictures. However, when the purpose of the motion estimation is to provide accurate interpolation between images, conventional block matching suffers from the problem that the blocks are situated in the original fields rather than in the fields to be interpolated, leading to possible errors in the calculated motion field. The invention uses two-sided block matching. The search window is shared between the two input fields so that the candidate motion vectors related to be candidate pixel blocks all pass through the same points in the field to be interpolated. Thus, the "current block" becomes a notional area in the field to be interpolated, and each of the two search windows extends to half the maximum motion vector in each direction. Each motion vector points forward to the forward field by half its value and backward to the backward field by half its value.

Abstract: A procedure for quantification of coefficients in a variable data rate image compression system, in the form of blocks and macroblocks, the system including circuitry for transformation of blocks of pixels into blocks of coefficients, circuitry for quantification of these coefficients, circuitry for storage of coded information before transmission, and circuitry for regulation of quantification as a function of the state of the circuitry for storage.

Abstract: There is disclosed a method for selecting programs in a digital video reception system adapted to receive digital data streams. The method comprises the steps of receiving information corresponding to program identification elements; displaying the identification elements in the form of a mosaic of elements (10) on a screen of the reception system, where the arranging of identification elements (10) in the mosaic is performed before transmission; receiving information describing the location of each program thus identified in a data stream broadcast by a transmitter (15); and selecting one of the programs by selecting at least one identifier clement. A device for selecting programs in a digital video reception system is also disclosed.

Abstract: The disclosure relates to a A digital filtering system of a signal, including a calculation circuit that calculates the average increase in amplitude .DELTA.X.sub.av (n) between two samples X(n), and an "output signal (Y(n)) circuit" that calculates a mean, weighted by a coefficient a, of the sample to be filtered X(n) and the previous sample Y(n-1) algebraically increased by said average increase in amplitude .DELTA.X.sub.av (n). The invention is applicable to digital signal processing.

Abstract: A device for extracting synchronization from a video signal. The device includes a dual-threshold synchronization pulse detection circuit, a first threshold device for detecting the leading edge of a pulse, and a second threshold device for detecting the trailing edge of the same pulse. The thresholds of the devices are defined by a synchronization pulse amplitude detector. The device includes sample-and-hold circuitry for bringing back the voltage stored by the amplitude detector in a storage capacitor to the voltage corresponding to the synchronization pulse, when a synchronization pulse is detected.

Abstract: There is disclosed a device for the generation of transfer functions by segments. One of the device comprises at least two sets of amplifiers having different gains; a comparator for comparing an input signal with at least one reference signal and a switch which is controlled by the output from the comparator, for switching between the at least two sets of amplifiers depending on the status of the comparator output. Where the at least two sets of amplifiers having different gains, at least one gain is greater than 1, and at least one gain is less than 1.

Abstract: The invention concerns a high storage capacity ROM-RAM disk and a process for reading and writing to the ROM-RAM disk. T he aim of the invention is to devise a ROM-RAM disk and a process making it possible to read ROM and RAM simultaneously, to read the ROM area and at the same time write to the RAM area and to provide the largest possible volume of memory. The invention comprises two alternative designs. In a first design a ROM-RAM disk contains an area having both ROM and RAM memory structures as of a certain radius or diameter, establishing therein, at a constant rotational speed, a scanning/writing speed which ensures a reading/separation of the data stored in the ROM-RAM structures. In a second design, the available storage area is taken up entirely by a ROM-RAM storage area, where RAM memory structures have a reduced data rate in order to form, a length of memory structures necessary for separating the data stored in the ROM-RAM storage area.

Abstract: There is disclosed an A/D conversion circuit comprising a first A/D converter for receiving an input signal of the A/D conversion circuit and providing a digital output signal, the first A/D converter having a restricted resolution, wherein the input signal passes through delay means to a first input of a subtraction stage. A first D/A converter operating on the output signal of the first A/D converter generates an analog output signal and feeds the analog output signal via an adding stage to a second and subtracting input of the subtraction stage, wherein the input signal of the first D/A converter passes through a correction algorithm unit to a second D/A converter. The output signal of the second D/A converter is fed to a second input of the adding stage, wherein the correction algorithm unit provides empirically determined data for D/A conversion correction. A low pass filter coupled to the output of the subtraction stage provides a low pass filtered and amplified output signal.