高畫質電視 數位電視 數位聲音廣播 可見度門檻 訊雜比 誤碼率 殘邊帶 編碼正交劃頻多工 High definition television HDTV Standard definition television SDTV Digital audio broadcasting DAB Threshole of visiblity TOV Signal to noise ratio SNR Bit error rate BER Vestigial sideband VSB Coded orthognal frequenby division multiplex COFDM