ATSC 8-VSB Data Frame [EtherGuide Glossary]

An ATSC 8-VSB Data Frame is the basic conceptual element employed in allocating 8-VSB transport packets between main (MPEG-2) service and M/H service. Each M/H slot is 156 bytes (29,328 bits)in length and encompasses around 12.1 ms of time. There are 4 M/H slots in each 8-VSB data frame.

The table below shows how the data within an individual ATSC M/H slot can be allocated between main and M/H service.

Whether a particular M/H slot contains all MPEG-2 packets or mostly M/H data and a few MPEG-2 packets is determined dynamically by the instantaneous needs of the main (MPEG-2)and ATSC M/H encoders and the various other units in the processing chain.

Each 8-VSB data frame spans 624 MPEG-2 packets (938,496 bits). In ATSC M/H usage, each 8-VSB data frame can contain either 72 MPEG-2 packets (108,288 bits) and 138 ATSC M/H packets (830,208) or, if no ATSC M/H data is present in a data frame, 624 MPEG-2 packets

Glossary