Abstract: A circuit, for processing high frequency digital signals minimizes radiation interference by reducing voltage swings at the circuit input. This is accomplished by forming circuit input structures, which exhibit very low input impedances. An example of such input circuitry is a common gate amplifier with a diode coupling the source electrode of the common gate amplifier to ground potential and input signal applied to the source electrode. Output signal is derived from the collector of the common gate electrode which has a further diode as a load circuit.

Abstract: A method and apparatus for producing a wipe sequence on a display device from incoming compressed video bitstreams, accomplishes the wipe function processing entirely in the compressed domain of the compressed video bitstreams. The old and new video bitstreams or sequences separately undergo a 2-dimensional convolution between its decoded DCT coefficients and stored DCT coefficients of a particular known wipe function. Each convolved bitstream is buffered with its quantization scale and then summed with the other. The summed output bitstream is used by a multiplexer along with each bitstream's decoded macroblock data to provide a seamed output bitstream. A controller controls the process such as frame correlation for convolution and output multiplexing of the summed bitstreams.

Abstract: In the case of the OFDM method, a large number of modulated carriers are transmitted using frequency division multiplexing, a spectrum having a virtually rectangular shape being produced as a result of the large number of carriers. In order to separate the carriers from one another again in the receiver, a Fast-Fourier-Transformation is carried out, it then being possible to separate each carrier cleanly from the others provided the carriers are exactly orthogonal with respect to one another. The carrier orthogonality can, however, be disturbed by various causes. Furthermore, the wanted signal must be separated from the undesired adjacent channel signals by analog or digital filtering in the receiver. In order to improve carrier and channel separation, the selectivity of the FFT filtering can be increased by enlarging the number of FFT components. However, this normally leads to an undesirably sharp increase in the computation complexity.

Abstract: A transmitted high definition television signal is represented by a packetized datastream configured as a sequence of data fields (FIG. 1) with a non-uniform data rate due to unequal inter-data overhead information intervals. Each data field is prefaced by a Field Sync overhead segment followed by 312 packetized data segments each with associated overhead information (FEC). At a transmitter (FIG. 33), a transport processor (14) forms data packets with associated headers and exhibits uninterrupted operation at a constant uniform data rate, while supplying a packetized datastream to a network (17) which constructs sequential data fields by inserting the non-data overhead information into the datastream. The transport processor is advantageously operated at a constant uniform data rate without having to modify the original data field structure to accommodate the needs of the data field construction network.

Abstract: An apparatus for processing a sequence of control commands for a unit (40) to be controlled is proposed. In this case, the apparatus has first decoding means (22) which are designed to decode a predetermined set of control commands. In this case, this predetermined set of control commands also contains an end command (CMD.sub.-- END), which indicates the end of a control command sequence. In order also to be able to process control command sequences having control commands which are not contained in the predetermined set, the apparatus has further decoding means (23) which are designed in such a way that when an unknown control command (SET.sub.-- BAREA) arrives, they react in the same way as when the end command (CMD.sub.-- END) from the predetermined set of control commands arrives. Undefined states are thereby prevented.

Abstract: An apparatus for pre-processing of a digital video data stream including luminance and chrominance pixel data, the apparatus comprising a plurality of pre-processing units including a horizontal filter unit and a vertical filter unit. The horizontal filter unit is located at an input side and the vertical filter unit is located at an output side of the preprocessing apparatus and wherein all read/write memory for storing data outputted from or inputted to the plurality of pre-processing units is contained in a single memory block.

Abstract: The present invention belongs to the field of transmission of a signal, using OFDM modulation (Orthogonal Frequency Division Multiplexing), from a transmitter to at least one receiver, via a transmission channel. The invention relates in particular to a device and a method for equalization of the received OFDM signal. Said equalization device is fitted into the reception system between a synchronization module and a module for binary decoding of the received signal, in which the receiver includes a recursive vector equalizer (10) capable of correcting the received signal in the time domain.According to the invention, the recursive vector equalizer (10) includes computation means (16; 22; 24; 40; 44; 46; 56) capable of estimating each transmitted symbol as a function of an estimate of the transmitted symbol which precedes the said transmitted symbol.

Abstract: A process for correcting the input-output correspondence of an analog-to-digital converter includes calculating the equation of the actual input-output correspondence, for known input values, during programmed conversion suspension periods. A comparison with the ideal conversion line subsequently makes it possible to calculate the necessary offset and gain corrections. The process is applied to the digital conversion of a plurality of component video signals.

Abstract: A transcoding method is performed by receiving a first bitstream of compressed image data having identifiable coding parameters. These parameters may relate to the GOP structure of pictures represented in the first bitstream, the size of the pictures represented in the first bitstream, whether the pictures represented in the first bitstream are field or frame pictures, and/or whether the pictures represented in the first bitstream define a progressive or interlaced sequence. First motion information is obtained from the first bitstream, and is used to extrapolate second motion information for a second bitstream of compressed image data. The second bitstream, which has one or more parameters different from the parameters of the first bitstream, is provided as a transcoded output.

Abstract: A multiplexer system includes a multiplexer (20) having plural inputs (1-K) and an output (15); plural channel processors (10) each having a control input, a data input for receiving an input signal, a complexity output for providing a signal representing the complexity of an associated input data signal, and a data output for providing a constant bit rate data signal to an associated input of the multiplexer; and a bit rate allocator (30) responsive to the complexity representing signals for providing bit rate control signals to the associated control inputs of the channel processors (10) as a function of the complexity representing signals, such that a bit rate of an output data signal from a channel processor (10) is a function of the complexity of an associated input data signal and to the combined of the input data signals.

Abstract: A field/frame conversion method for compressed digital video, especially MPEG type video, having mixed field/frame mode macroblocks in the DCT domain utilizes a 1-D IDCT/DCT approach rather than the conventional 2-D IDCT/DCT approach. A vertical 1-D IDCT is performed on the DCT domain mixed field/frame mode macroblock to obtain a horizontal 1-D DCT domain macroblock. Thereafter, field/frame conversion is performed on the horizontal 1-D DCT domain macroblock to yield a field or frame mode horizontal 1-D DCT domain macroblock, depending on the required conversion. Finally, a vertical 1-D DCT is performed on the field/frame converted horizontal 1-D DCT domain macroblock to yield a 2-D DCT domain macroblock.

Abstract: Packetized program information used in video processing and storage medium formats includes multiple text strings. A decoder decodes packetized program information containing multiple text strings associated with a program. The decoder determines from a first indicator in the packetized program information a type of coding and compression employed in encoding a first text string. The decoder decodes the first text string with a decoding function selected in accordance with the determined type of coding and assembles decoded text string elements to form an output text string.

Abstract: A process and apparatus for converting an MPEG-2 bitstream into an SMPTE-259 compatible bitstream is characterized by a frame rate converter which is selectively enabled to drop every 1001st frame of the incoming MPEG-2 bitstream depending on the input bitstream frame rate. If the input bitstream frame rate is other than 29.97 or 59.94 Hz, a frame dropper is enabled to discard every 1001st frame. The present converter can convert many different types of input bitstreams, such as all I types, IPIP types, or complex GOP types containing I, P, and B frames. The enabled frame dropper will drop either the I or P frame if it occurs as the 1001st frame, but if the 1001st frame is of the B frame type, the pixel information of the B frame is dropped. This produces a minimum in loss of information during the conversion. The format converter allows existing SMPTE-259 routing equipment to route and utilize MPEG-2 bitstreams, such as HDTV applications.

Abstract: A system for equalizing an input signal including a datastream modulated on a carrier, with respect to both transmission channel distortions and local receiver distortions, includes a network for frequency downshifting the input signal, a controlled non-recursive filter (20) responsive to the downshifted input signal, and a demodulator (30) for receiving an output signal from the controlled filter. A signal processing network, including a filter network with a transfer function (40, 60, 80, 100) which is the inverse of the transfer function of the controlled filter, responds to an output signal from the demodulator for producing output control signals. The control signals are coupled to a coefficient control input of the non-recursive filter for equalizing the signal with respect to both transmission channel and receiver distortion.

Abstract: A decoder conditional access system incorporates different encryption systems for providing access to programs derived from different sources. A conditional access processor for processing encrypted program data and an associated encryption code includes a first algorithm means for decrypting the encryption code to provide an encryption key. The conditional access processor also includes a second algorithm means for encrypting the encryption key and the second encryption algorithm is different to the first encryption algorithm. A datastream representing the program is generated from encrypted program data and an associated encryption code. The encryption code is decrypted to provide an encryption key using a first algorithm. The encryption key is encrypted using a second algorithm different to the first encryption algorithm and the program datastream is formed from the encrypted program data and the encrypted encryption key.

Abstract: A symbol timing recovery (STR) error detector includes a complex multiplier and a Gardner-type symbol timing error estimator for operation with carrierless amplitude phase (CAP) signals. Quadrature Ir and Qr signals from the system are input to the complex multiplier, which also receives signals from a numerically controlled oscillator operating at the CAP center frequency. The output of the complex multiplier is provided to the input of the Gardner STR error estimator. An added frequency shift allows the Gardner error estimator to function with CAP signals. The output from the error estimator is provided to a loop filter the output of which is provided to an oscillator which generates the symbol timing information for a symbol sampling network.

Abstract: In the case of the storage or transmission of moving images, it is frequently necessary to reduce the large number of information items by means of suitable compression methods. In order to estimate the movement, the image to be coded is in this case split into blocks, and each of these reference blocks R is compared with blocks of the same size of the preceding image, and a movement information item is derived. Conventional methods for movement estimation in this case use all the pixels in the reference block R and in the search area S. Since this very complicated method requires very fast, and thus expensive, hardware, the so-called quincunx undersampling is applied to the search area S. In the case of the reference block R, one quincunx undersampled pixel is used for even parity of the movement vector and the other quincunx undersampled pixel is used for odd parity, depending on which position is being investigated.

Abstract: Various methods for terrestrial transmission of digital broadcast signals as DVB, HDTV-T and DAB signals are known. One of these methods is the OFDM method, where the transmitted signal includes a multiplicity of modulated carriers. These carriers are separated in the receiver by means of a Fast Fourier Transformation (FFT). Before being transposed in the frequency domain by the FFT, the analog signal must be sampled. For this purpose a local oscillator controls the timing in front of the FFT. Oscillator imperfections like jitter and frequency offsets can degrade the accuracy of the sampling operation and therefore introduce intercarrier interferences after the FFT. A feedback loop combining the AFC and CPEE process has been designed in order to correct frequency deviations and to reduce jitter of the signal without introducing significant phase noise.

Abstract: Apparatus and method for receiving a QAM signal using a backward compatible hierarchical coding scheme to increase data transmission using finer constellations, while maintaining compatibility with existing Direct Broadcasting Satellite (DBS) systems. The apparatus employs multiple stages of decoders such that the finer constellations of the QAM signal are unraveled at different stages.

Abstract: The invention relates to a device for blockwise estimation of motion. This device includes on the one hand a matrix array (300) for calculating an error function, the said array including storage elements (S, 406, 407) for plural blocks (a, a') of current pixels and means (403) for switching between the storage elements corresponding to the various blocks and on the other hand a memory (801) for feeding the said array with pixels of a search window, linked to the said array.The device according to the invention is characterized in thatthe said memory (801) is a random access memory,the said memory contains a band of the search window corresponding to the entirety of the current blocks stored in the array (300),the said device including means (812) for read-addressing partial sections of the said band of the memory as a function of the block processed (a, a') by the said array, the said sections being introduced column by column into the said array.