Abstract: A digital transmission system and method that improves upon the ATSC A/53 HDTV signal transmission standard includes: a first forward error correction (FEC) unit for encoding packets belonging to each of robust and normal data bit streams; a robust processor unit for receiving robust packets comprising priority data and processing the packets for generating the robust bit stream; a trellis encoder unit for producing a stream of trellis encoded data bits corresponding to bits of the normal and robust streams, the encoder employing mapping of encoded data bits of said robust packets into symbols according to one or more symbol mapping schemes; and, an optional second forward error correction (FEC) encoding unit for ensuring backward compatibility with a receiver device by reading in only packets of the robust bit stream and enabling generation of parity bytes only for the robust stream packets; and, a transmitter device for transmitting the robust bit streams in a backwards compatible manner, separately or in c

Abstract: This disclosure describes a flexible digital transmission system that improves upon the ATSC A/53 HDTV signal transmission standard. The system includes a digital television signal transmitter for generating a first Advanced Television Systems Committee (ATSC) standard 8-VSB bit stream and, for generating an encoded new bit stream capable of transmitting high priority information bits, wherein symbols of the new bit stream are capable of being transmitted according to a transmission mode selected from group comprising: a 2-VSB mode, a 4-VSB mode, and a hierarchical-VSB (H-VSB) transmission mode. Each respective 2-VSB, 4-VSB, and H-VSB mode is characterized as having symbols mapped according to possible symbol values from an alphabet comprising respectively, {−7, −5, 5, 7}, {7, 3, −3, −7}, and {7, 5, 3, −3, −5, −7}.