Abstract: An elementary two-stream transport multiplexer provides for the addition of services contained in a transport stream to a pre-existing transport stream. The elementary multiplexer includes a pair of transport demultiplexers, a processor and a transport remultiplexer. The demultiplexers demultiplex a pair of input transport streams to their constituent service components and service control information tables. The service control information tables are routed to the processor which combines and reconfigures the information within the tables to provide a single set of output service control information tables. The demultiplexers filter the service components based on the output service control tables. The transport remultiplexer multiplexes the output tables with the filtered streams to provide an output transport stream.

Abstract: A system and method are disclosed for digitally representing reference and data signals transmitted in the vertical blanking interval (VBI) of an analog television waveform such as NTSC or PAL. The system includes means for compressing the digital representation of the VBI signals. A broad range of reference and data signals is capable of being represented. The compressed representations of the VBI signals are particularly suitable for inclusion in an MPEG2 compliant signal carrying compressed digital video and audio.

Abstract: A method is disclosed for supplying arbitrary types of information in a digital signal conformant to the structures defined in ISO standard ISO/IEC 13818-1, known generally as MPEG2 Systems. The method extends Program Stream and Transport Stream structures by application of principles developed for standardization of bidirectional data communications protocols to define a universal messaging syntax applicable to all types of information, including Internet data streams, VBI data streams, other types of data streams, as well as MPEG2 video, audio, and control; to define a multiplexing structure that is independent of the details of the MPEG2 signal structure; and to define a scheme for addressing such enhanced MPEG2 signals, or portions of signals, to individual decoders or to groups of decoders.

Abstract: A luminance notch filter for preventing color crosstalk adaptively attenuates a SECAM luminance signal depending on the strength of the luminance signal using digital filtering techniques. The adaptive luminance notch filter includes a bandpass filter centered at the chrominance band that is operative to receive the input luminance signal and provide a bandpass filtered luminance signal. The bandpass filtered luminance signal is multiplied by a gain factor and the multiplied luminance signal is subtracted from the input luminancee signal to provide a notch filtered luminance signal. A detector coupled to the bandpass filter output detects the signal strength of the bandpass filtered luminance signal and the gain factor is adapted in accordance with the detected signal strength. The bandpass filter comprises an infinite impulse response (IIR) filter that is preferably an all-pole IIR filter of at least 3.sup.rd order.

Abstract: A fractionally-spaced adaptively-equalized self-recovering digital receiver includes a fractionally-spaced adaptive filter for equalizing channel distortion which includes means for adaptively adjusting the coefficients of the fractionally-spaced filter with a self-recovering (blind) algorithm or a decision directed algorithm; means for changing the timing at which the data is sampled; means for estimating the sampling frequency offset in order to derive the optimal timing; means for synchronizing the signal resampling at the symbol rate using the statistics of the received data samples; means for evaluating the profile of the equalizer coefficients; and means for tracking carrier frequency offset.

Abstract: An optimal multiplexing method is disclosed which allows buffers to be two packets in depth. For a plurality of buffers, with each buffer associated with a packetized data stream, packets are received at respective buffer input rates. The buffers are serviced at a service rate at least equal to a sum of the buffer input rates. For each buffer, once a full packet has been received therein, a time interval until that buffer is expected to reach its buffer depth is determined. The buffer having the least time interval is then serviced first, such that overflow of the buffers is avoided.

Abstract: A method of carrier tracking in a digital receiver includes adjusting the phase of an equalized signal by a phase correction to compensate for a carrier frequency offset. For a small carrier frequency offset the phase correction is based on a first estimate of phase error and phase velocity of the equalized signal. For a large carrier frequency offset the first phase velocity estimate is controlled by a second phase velocity estimate based on rotation of the data constellation.

Abstract: A method and apparatus for 45.degree. phase ambiguity resolution for one coded bit per symbol 8PSK modulation resolves phase ambiguity by selection of pre-differential encoders. A trellis encoder for 8PSK modulation of the type in which input data bits are encoded to a three-bit symbols includes a differential encoder, a convolutional encoder and first and second encoding assemblies. A decoder for decoding trellis coded data of 8PSK modulation includes a Viterbi decoder, a differential decoder, a convolutional decoder and first and second decoder assemblies. Each of the encoding and decoding assemblies includes multiplexing logic for selecting from among possible data paths according to a phase invariant scheme.

Abstract: A fractionally-spaced adaptively-equalized self-recovering digital receiver includes a fractionally-spaced adaptive filter for equalizing channel distortion which includes means for adaptively adjusting the coefficients of the fractionally-spaced filter with a self-recovering (blind) algorithm or a decision directed algorithm; means for changing the timing at which the data is sampled; means for estimating the sampling frequency offset in order to derive the optimal timing; means for synchronizing the signal resampling at the symbol rate using the statistics of the received data samples; means for evaluating the profile of the equalizer coefficients; and means for tracking carrier frequency offset.