Abstract: A data frame structure for a digital information signal comprises a first fixed number of repetitive data segments each containing a second fixed number of M-level symbols representing a plurality of data bytes and a data segment sync character. The frame further includes a header segment including a frame sync code and a mode code defining the value of M for the data frame. The data frame incorporates error correction blocks and is configured to provide an integral number of data bytes and error correction blocks for each of a plurality of different values of M.

Abstract: A symbol to byte converter converts multilevel symbols into data bytes. The bits of each M level symbol are written to a parallel register and read out serially to a serial register under control of an 8 times symbol clock. Successive groups of eight bits are read out in parallel from the parallel register with a byte clock to form the data bytes.

Abstract: An ATV system encodes variable length elementary streams of data into a multilevel symbol signal comprising a plurality of multiplexed fixed length data packets without sync information. The fixed length data packets are arranged in fields of repetitive data segments, each of which includes a data segment sync and each field of which includes a field sync. The fields of data segments are transmitted as suppressed carrier VSB modulation. In an ATV receiver, the data segment sync is used to generate a timing signal that identifies the beginning of each fixed length data packet. In one embodiment, a packet sync signal is inserted into each recovered fixed length data packet for recovering the elementary streams of data. In another embodiment, recovery of the elementary streams of data is accomplished without inserting a packet sync signal.

Abstract: A convolutional interleaver or deinterleaver comprises an address signal generator for repeatedly generating [(B-1)N/2]+1 sequences of address signals, where B is a desired interleave depth and N is a value equal to or greater than the number of data bytes in a R-S block of the data stream. Each of the sequences corresponds to a respective row of a B column matrix, the first column of which comprises [(B-1)N/2]+1 consecutively numbered values. Each remaining column comprises the preceding column rotated by an integer multiple of N/B. The address signals are applied to a memory having [(B-1)N/2]+1 storage locations for reading the data stored at the address memory location and then writing the current data byte to the same memory location.

Abstract: An ATM/MPEG system receives individual MPEG programs of different constant bit rates from a plurality of servers. The individual programs are converted into ATM cells which are transmitted along an ATM network at a constant bit rate. The ATM cells are received and arranged into queues of the individual programs. A microprocessor prioritizes the queues based upon the bit rates of the MPEG programs. The queues are multiplexed to 16 VSB modulators based upon their priority assignments with the highest priority queues being sent to the modulators in preference to lower priority queues.

Abstract: A digital data processing system receives compressed variable length encoded digital data in the form of variable length codewords in contiguous variable speed Blocks of data. The boundary signals between adjacent codewords are determined and a demultiplexer sequentially sorts the serial digital data among a plurality of parallelly connected buffers for reducing the bit read speed of the buffers. A corresponding plurality of variable length decoders decodes the data from the buffers and outputs the data in parallel form to a multiplexer where it is reassembled into a serial expanded data stream. The incoming data includes selector information in fixed length headers that are separated, buffered and variable length decoded for controlling the demultiplexer. In one aspect of the invention, the data is sorted into substantially equal sized groups of integral codewords for equalizing the loading of the parallel buffers.

Abstract: A television signal transmission system comprises a multiplexer for combining a compressed video data signal and one or more auxiliary data signals to form a multiplexed signal for transmission over a channel of fixed bandwidth. The multiplexer is controlled to vary the ratio of the components comprising the multiplexed signal to insure satisfactory reproducible image quality in response to the received compressed video data signal. The compressed video data signal may be buffered prior to combination with the auxiliary data, in which case the multiplexer is also further controlled to vary the ratio of the components comprising the multiplexed signal to maintain the fullness of the buffer at an acceptable level.

Abstract: A digital data processing system receives compressed variable length encoded digital data in the form of variable length codewords in contiguous variable speed Blocks of data. The boundary signals between adjacent codewords are determined and a demultiplexer sequentially sorts the serial digital data among a plurality of parallelly connected buffers for reducing the bit read speed of the buffers. A corresponding plurality of variable length decoders decodes the data from the buffers and outputs the data in parallel form to a multiplexer where it is reassembled into a serial expanded data stream. The incoming data includes selector information in fixed length headers that are separated, buffered and variable length decoded for controlling the demultiplexer. In one aspect of the invention, the data is sorted into substantially equal sized groups of integral codewords for equalizing the loading of the parallel buffers.

Abstract: A microprocessor controlled television receiver includes a decoder input for receiving coded data streams for controlling functions of the television receiver from a remote and a local keyboard. Microprocessor based arbitration means scan the keys of the local keyboard and control operation of a gate for selectively coupling the data streams from the remote keyboard and the local keyboard to the decoder of the television microprocessor. The arbitration means assures noninterference between the respective data streams.

Abstract: An electronic musical instrument includes a keyboard having a plurality of keys, each depressed key being identified by a uniquely developed multibit code. Each of a plurality of tone generators, substantially less in number than the number of keys characterizing the keyboard, is operable in response to each of the multibit codes for producing a tone signal having a frequency corresponding to the pitch of the associated depressed key. Each depressed key is assigned for playing through one of the tone generators by a control circuit, the control circuit being responsive to the condition wherein all of the tone generators have been assigned to previously played keys for assigning a newly played key for playing through the tone generator which was assigned to the oldest released one of the previously played keys.