Proposed Digital HDTV broadcast modulations

Format	Modulation	Bandwidth
DigiCipher	32 QAM or 16 QAM	4.88 MHz
DSC-HDTV	2 and 4 level VSB	5.38 MHz
AD-HDTV	SS QAM	5.2 MHz
CCDC	32QAM or 16QAM	5.287 MHz

DSC-HDTV

(DSC)-HDTV broadcasting was a proposed method to gradually introduce simulcast digital spectrum-compatible (DSC) transmissions that allowed the reuse of the older National Television Systems Committee (NTSC) equipment. This would have deferred a significant portion of the investment in new equipment.

AD-HDTV

(AD-HDTV) Advanced digital high definition television - Proposed by the (ATRC) Advanced Television Research Consortium and Thomson Consumer Electronics Inc,
This was the only system that included a packetized data structure with headers and descriptors as a critical enable concept that geve it more flexablity of the other systems.

DigiCipher

Proposed by the American Television Alliance(General Instrment Corp. and MIT )

CCDC

CCDC (Channel Compatable DigiCipher) also proposed by the American Television Alliance(General Instrment Corp. and MIT ) COFDM

GA-HDTV

Grand Alliance System, this is the current standard pushed by the FCC and ACATS. A concensus to use MPEG-2 was made. (all the other systems used mpeg like compresion but were incompatable).

Uses Viterbi FEC , Trellis coded 8-VSB modulation that delivers 19,392,658 b/s Bits Per Second in a 6 Mhz terrestrial simulcast channel.
This consist of 204 or 208 Byte Data packets Made up of Sync/3 Hrd/184 Payload/ 16 or 20 FEC. This is essentialy a ISO 13818-1 MPEG2 Transport Stream made up of 188 Byte Packets + a 20 Bit Reed-Solomon(204,188,T=8) Forward Error Correction capable of correcting up to 8 or 10 Bit flips.

RF Frequency 55.25MHz to 859.25MHz

SMPTE-310M: 19,392,658 b/s for 8 VSB, and 38,785,316 b/s for 16 VSB.