mobile / handheld data is received in an m / h frame equivalent in size to exactly 20 vsb data frames . each vsb frame contains an odd vsb field and an even vsb field , and each of the vsb fields includes one field sync segment and 312 data segments . the m / h frame includes main data and m / h data , and the m / h data has more robust coding than the main data . the m / h frame is received and an mpeg encoded transport stream derived therefrom is outputted . frame registration is found so as to find a structure of the m / h frame in the mpeg encoded transport stream . based on the structure of the m / h frame , the m / h data is randomized . based on the structure of the m / h frame , block mode data is located within the randomized m / h data . the m / h data is decoded using the block mode data .