Abstract: A method and apparatus for providing bi-directional communication in systems broadcasting multi-carrier signals removes at least one sub-carrier to form an intra-spectral gap within a multi-carrier broadcast signal. The intra-spectral gap is used to provide a bi-directional channel for propagating ancillary data signals between network elements in a broadcast communication system.

Abstract: A system of the present invention addresses the difficulty of aligning a reference sync byte at the beginning of a data packet during situations where the system experiences severe problems such as arbitrary resets/restarts or transmission disturbances. Specifically, the sync byte at the beginning of the data packet is automatically aligned with the beginning of a data acquisition interval when data is requested, even when there are arbitrary system resets/restarts. The alignment of the first data packet following a system reset is facilitated by the use of a Start Of Packet flag concurrent with the reference byte, together with a controlled logic network.

Abstract: In a digital television signal processing system, a special codeword, a Packet Alignment Flag (PAF), is inserted into an MPEG codeword bitstream to signify the presence of a Group of Pictures (GOP). The PAF immediately precedes a Picture Start codeword for an "I" frame, which initiates a GOP. A data packet under construction when a PAF appears is terminated since a GOP is intended to begin at a packet boundary. Such termination may result in an abbreviated packet of MPEG codewords less than a prescribed number of bits needed to complete a data packet. The last word of each packet is designated as such to facilitate the subsequent combining of data packets with respective headers. An incomplete data packet is filled with null (zeroed bits) words to make up a complete data packet with a prescribed number of bits.

Abstract: In a digital television signal processing system, a special codeword, a Packet Alignment Flag (PAF (14), is inserted into an MPEG codeword bitstream to signify the presence of a Group of Pictures (GOP). The PAF immediately precedes a Picture Start codeword for an "I" frame, which initiates a GOP. A data packet (12) under construction when a PAF (14) appears is terminated since a GOP is intended to begin at a packet boundary. Such termination may result in an abbreviated packet of less than a prescribed number of codewords needed to complete a data packet. The last word of each packet is designated as such to facilitate the subsequent combining of data packets (12) with respective headers (18). An incomplete data packet is filled with null (zeroed bits) words to make up a complete data packet with a prescribed number of words.

Abstract: In a digital television signal processing system, a special codeword, a Packet Alignment Flag (PAF), is inserted into an MPEG codeword bitstream to signify the presence of a Group of Pictures (GOP). The PAF immediately precedes a Picture Start codeword for an "I" frame, which initiates a GOP. A data packet under construction when a PAF appears is terminated since a GOP is intended to begin at a packet boundary. Such termination may result in an abbreviated packet of less than a prescribed number of codewords needed to complete a data packet. The last word of each packet is designated as such to facilitate the subsequent combining of data packets with respective headers. An incomplete data packet is filled with null (zeroed bits) words to make up a complete data packet with a prescribed number of words.

Abstract: A method is disclosed for optimizing the operation of a packet transport system generating a packet stream carrying a plurality of component signals, and includes the following steps. First the packet stream is partitioned into successive groups, each group containing a predetermined number of packet slots. A plurality of lists are maintained, one associated with each packet slot in a group. A packet stream is generated by placing data representing a component signal selected in response to entries in the list associated with that packet slot into the packet slot. The contents of the plurality of lists are updated based on a predetermined parameter.