AT1 Technologies inc , Yardley 19061. PA t ZeniUl Elecrromcs. Lincolnshire 6W69. IL Absslruo-A new Enhanced VSB (E-VSB) transmlsion system has been propmed to impmw the North-American HDTV terrestrial bmPdeatL The system allows better recppuon lor portable, mobile, and iodoar melvers, by meam 01 1wo backward eompsllbie robus1 and rcalahle data 111981116, socallad U2 rate and 114 rata, that c m c o w k t with the n o m 1 slream. One originality of tho system Ue in the possibility for the receiver l o enhance the n o r m i lrnnrmlulon mode by C O~. blning the i d o r m l i m provided by the hro robask s b m m to impmva mcdallon or channel multipath. The Impmwm~nt 01 the m i n sewice depen& on the codimg mechanism vsDd for the enhanced atre" and tho number and tho position or the enhanced symbok in the VSB lrame. In lhlr contribution, we iiIyslr~te the coding and the NormaUEnhanced p c b l multipiedng mechanirms lhat are used lo achieve this goal.