The space occupied by one full HD channel on a transponder is equal to space occupied by 4 SD channels, thats the main criteria.... The upscaled channels dont occupy so much space, SO even if they may be replacing the upscaled channels, they need to free up transponder space to bring a full HD channel in place of an upscaled. Its not a mere replacement.. EQUATION IS SPACE FOR 1 FULL HD CHANNEL = SPACE REQUIRED FOR 4 SD CHANNELS.. You can imagine how much transponder space it requires for an full HD 1080i channel to be introduced.... Thats why dish TV is removing upscaled channels, as i told all DTH operators wants to use transponder space effectively..