Digital transmission system for an enhanced ATSC 8-VSB system

A method for transmitting digital signals comprising encoded bit streams including a normal bit stream and a robust bit stream, said method comprising the acts of:

• encoding the normal bit stream and the robust bit stream in a first forward error correction (FEC) unit to form an encoded normal bit stream and an encoded robust bit stream;
• processing said encoded robust bit stream to generate a processed robust bit stream;
• producing a stream of trellis encoded data bits from said encoded normal bit stream and said processed robust bit stream, said stream of trellis encoded data bits corresponding to bits of said encoded normal bit stream and said processed robust bit stream;
• reading in only portions of said trellis encoded data bits corresponding to said bits of said processed robust bit stream from a trellis encoder unit and enabling generation of parity bytes only for said processed robust bit stream in a second forward error correction (FEC) unit;
• and
• transmitting said stream of trellis encoded data bits corresponding to said bits of said encoded normal bit stream and said bits of said processed robust bit stream including said parity bytes over a communications channel to a receiver device.

A high-definition digital television signal transmission system for transmitting encoded MPEG-compatible data packets for receipt by a digital television receiver device, said packets including a normal bit stream and a robust bit stream, said system comprising:

• a first forward error correction (FEC) unit for formatting the normal bit stream and the robust bit stream;
• a robust processor unit for receiving and processing said encoded robust bit stream to generate a processed robust bit stream and passing through said encoded normal bit stream as an unaltered encoded normal bit stream;
• a trellis encoder unit for receiving said unaltered encoded normal bit stream and said processed robust bit stream, and for producing a stream of trellis encoded data bits corresponding to bits of said unaltered encoded normal bit stream and bits of said processed robust bit stream, said trellis encoder unit mapping encoded data bits of said encoded robust bit stream into symbols according to one or more symbol mapping schemes;
• a second forward error correction (FEC) unit for reading in only portions of said trellis encoded data bits corresponding to said bits of said processed robust bit stream from the trellis encoder unit and enabling generation of parity bytes only for said processed robust bit stream;
• and
• a digital television signal transmitter device for:
• transmitting said stream of trellis encoded data bits in a backwards compatible manner over a communications channel to said receiver device, said stream of trellis encoded data corresponding to said bits of said unaltered encoded normal bit stream and said bits of said processed robust bit stream including said parity bytes;
• and
• transmitting bits for receipt by said receiver device including information to enable the receiver device to correctly decode the symbols according to the one or more symbol mapping schemes;
• and
• wherein the receiver device is capable of at least one of:
• (i) receiving the stream of trellis encoded data bits and processing said processed robust bit stream as null packets and (ii) receiving the stream of trellis encoded data bits and processing said processed robust bit stream at a lower Threshold of Visibility (TOV) compared to the normal bit stream.