Abstract: A method is proposed for checking convergence in fractal image coding. In this case, a digitized image is divided into a number of range blocks (R.sub.i, R.sub.i+1) and into a number of domain blocks (D.sub.j, D.sub.k). A similar domain block is determined in relation to each range block. If necessary, in this process a transformation of a domain block is undertaken in order to map the domain block onto a range block. The assignment of the domain block to the range block including the transformation parameters represents the fractal code for the image. A reduced transformation matrix is set up to check convergence of the fractal code. The largest absolute eigenvalue of the transformation matrix is determined approximately. The entire method can be carried out in this case hierarchically. In a first approximation step, at least the row sum norm of each row of the reduced transformation matrix is checked. In further steps, further rows are combined to form square matrices of higher dimension.

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: A timing recovery system for a digital signal receiver receives a signal, representing successive symbols, from a transmitter. The symbols are subject to exhibiting multiple symbol rates. The system derives a sample enable signal from the received input signal and employs a single, fixed frequency oscillator. A source of samples representing the received signal are sampled at a fixed frequency. An interpolator is coupled to the sample source and is responsive to a control signal. The interpolator produces samples taken at times synchronized to the successive symbols from the transmitter. A phase error detector is coupled to the interpolator, detects a phase error between the sample times of the transmitter synchronized samples produced by the interpolator and times of the successive transmitter symbols, and supplies a phase error signal. The phase error signal is coupled to one input terminal of a summer and a source of a nominal delay signal is coupled to the other.

Abstract: Apparatus for interposing additional optical elements in the optical path of an optical read/write device includes said additional element mounted on a carrier pivotally mounted on a lens carrier which is subject to lateral translation. Stops on the carrier to which the additional element is mounted engage actuators arranged at the limits of lateral travel of the lens carrier, which limits are beyond the recordable areas of the recording medium. The engagement of the actuators with the carrier causes the carrier to pivot and either insert or remove the additional optical element in the optical path of the apparatus. Magnetic retainers are included to prevent the additional element from moving from the desired position.

Abstract: Apparatus for determining a complexity measure of a data signal is disclosed which includes an encoder, having an input terminal responsive to a data input signal and a data output terminal producing a coded output signal representing the data input signal at a constant bit rate. The encoder includes a variable quantizer, responsive to the data input signal, for producing a quantized signal, representing the data input signal, having a quantizing step size defined in response to a quantizing step size control signal. A bit rate regulator produces the quantizing step size control signal in response to the bit rate of the coded output signal and a quota input signal. A complexity analyzer generates a complexity representative signal related to the quantizing step size and the bit rate of the coded output signal.

Abstract: A complexity determining apparatus is disclosed which comprises a source of a data signal and a subsampler system, coupled to the data signal source, for producing a subsampled signal representing the data signal. A variable bit rate (VBR) encoder is responsive to the subsampled signal and produces an encoded signal representing the subsampled signal. A counter accumulates the number of bits in the encoded signal and produces a complexity representative signal corresponding to the accumulated number of bits.

Abstract: A CAP signal is processed by a QAM demodulator network. The QAM network causes the CAP signal to rotate about its center frequency, which rotation is removed prior to conveying the CAP signal to utilization networks. In an analog implementation, the CAP signal is frequency upconverted to be centered at Fad/4 so that the QAM processor can use the usual 1, 0, -1, 0 demodulation sequence to bring the CAP signal to baseband. Alternatively, using digital techniques, frequency upconverting is not needed and the 1, 0, -1, 0 demodulation sequence is replaced with a Numerically Controlled Oscillator and full multiplier to allow the QAM processor the bring the CAP signal to baseband.

Abstract: The present invention to provides for information carriers of different storage densities, a recording and/or playback device which is compatible or can be used for different optical information carriers despite a functional relationship which to be satisfied between the size of the information memory location or pit size and the size of the light spot, without changing the wavelength of the laser used or changing the numerical aperture of the objective lens. In order to operate optical information carriers of different storage densities, use is made of an optical system which has a wavelength and numerical aperture matched to the highest storage density, provides a plurality of secondary beams matched to the respective track width, and has a number of secondary beam detector pairs which corresponds to the number of different information carriers.

Abstract: A reproducing and/or recording device for reproducing, or for recording on, an optical recording medium, having a tracking sychronization circuit (1), which has a variable center frequency generator (12, 13). The tracking synchronization circuit (1) can be operated with different center frequencies depending on application, and this has the advantage that identically designed tracking synchronization circuits (1) can be used for different purposes. It is advantageous that adaptive adjustment of a center frequency once prescribed is additionally possible during operation, thus increasing the capture range of the tracking synchronization circuit.

Abstract: A distributed computer system is disclosed which comprises a source of a continuous data stream repetitively including data representing a distributed computing application and a client computer, receiving the data stream, for extracting the distributed computing application representative data from the data stream, and executing the extracted distributed computing application.

Abstract: The invention relates to a method and a device for producing a scanning device, also termed a pick-up, for optical recording media, which can be produced with a low outlay and thus cost-effectively, and in comparative terms has a low tilt of the objective lens and improved guidance properties. According to the invention, during the connection of an objective lens holder and actuator base plate, a prestress is applied to wires provided as elastic support of the objective lens holder on an actuator base plate. Scanning devices produced according to the invention for optical recording media have a low tilt of the objective lens and improved guidance properties.

Abstract: A satellite signal receiver includes an input demodulator followed by a Viterbi decoder and a Reed-Solomon decoder. A received signal is encoded with information including error-representative information, and exhibits an error correction code rate which is a function of the power level of a satellite transmitted signal. The demodulator produces control signals representing the presence or absence of synchronism with the received signal, and signal quality (e.g., signal-to-noise ratio). The Reed-Solomon decoder produces a control signal indicating whether or not error detection and correction is occurring properly. These control signals are sensed by a control network to change the code rate of the Viterbi decoder if necessary.

Abstract: A device for reading from or writing to an optical recording medium is disclosed which has at least two information carrier layers spaced apart from one another, as well as a light source, an optical unit and a detection unit. The device permits a plurality of information carrier layers to be read from and/or written to simultaneously using light of a single wavelength. A partial beam generating element emits two polarized beams which differ in terms of polarization direction and propagation behaviour.

Abstract: A transmitted high definition television signal is represented by a packetized datastream configured as a sequence of data fields with a non-uniform data rate due to different types of different duration non-data overhead information. Each data field is prefaced by a Field Sync overhead segment followed by 312 packetized data segments each with associated overhead information. At a transmitter, a transport processor forms data packets with associated headers and exhibits uninterrupted operation at a constant uniform data rate, while supplying a packetized datastream to a network 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: A television signal receiver for processing an HDTV signal transmitted in a vestigial sideband (VSB) format includes input complex filters shared by a timing recovery network (30) and a carrier recovery network (50). The filter network includes a pair of upper and lower band edge filters (20, 22) mirror imaged around the upper and lower band edges of the VSB signal for producing suppressed subcarrier AM output signals. The timing recovery network includes a phase detector (28, 38, 62) and responds to an AM signal derived from the two filters (via 26) for synchronizing a system clock (CLK). The carrier recovery network (50) also includes a phase detector (54, 60, 62, 64), and responds to outputs from one or both of the filters for producing an output error signal (.DELTA.) representing a phase/frequency offset of the VSB signal. The error signal is used to reduce or eliminate the offset to produce a recovered baseband or near baseband signal.

Abstract: A method and apparatus for scaling the bitstream of a compressed video signal includes partial decoding hardware (38, 41) to permit excising of higher frequency AC DCT coefficients or re-quantizing quantized data with a coarser quantization factor. The scaling is performed on a block (macroblock) basis in a manner which linearly scales the amount of compressed data per block. An analyzer (40) generates a profile of cumulative partially decompressed data over a video frame, and bitstream scaling (42) is performed in a manner which insures that a profile of the scaled signal substantially comports with the profile of the original data.

Abstract: Apparatus for asynchronously generating control signals (CONTROL) is disclosed including a plurality of sources (5) of asynchronous data signals and a plurality of data processing channels (10, 14), each processing one of the data signals in response to a control signal (CONTROL). Each of a plurality of parameter determining circuits (10, 16) produces a signal (COMPLEXITY) representing a parameter of one of the data signals. A data sampler (30) samples the signals (COMPLEXITY) from all of parameter determining circuits (10, 16) substantially simultaneously at predetermined sampling time intervals. A control signal generator (30) generates control signals (CONTROL) for the data processing channels (10, 14) having values based on the sampled parameter representative signals (COMPLEXITY) and the preceding sampling time interval.

Abstract: A receiver is arranged for receiving a transmitted quadrature amplitude modulated (QAM) signal representing successive symbols, and including an in-phase (I) component and a quadrature (Q) component. In such a receiver, a timing recovery system includes a source of samples representing the QAM signal produced at a fixed frequency. A first chain of processing circuitry for the I component includes a first demodulator, coupled to the sample source, for demodulating the I component of the QAM signal to baseband; and a first interpolator, coupled to the first demodulator and responsive to a control signal, for producing I component samples taken at times synchronized to the transmitted symbols.

Abstract: An optical recording and/or playback system having tracking and focus regulating circuits. Mechanical shock and/or disc defects are detected and the adverse effects on the tracking and focus regulating circuits are reduced.