An alternative modulation scheme in digital television for terrestrial broadcasting (DTTB)

A particular use of a coded-OFDM with guard-interval (ICOFDM), to provide transmission with one enhanced definition (EDTV) or two standard definition (SDTV) TV signals in a 7 MHz bandwidth channel, is illustrated in the present paper. Frequency arrangements of the RF channel and TV filters features are also suggested. Digital communications using conventional 8PSK signals and standard receiver techniques might have high bit error rates in a Rayleigh fading environment for the inability to track absolute phase during fades. Differential encoding can reduce this false phase locking problem. To combat this problem a differential encoding scheme is used combined with a constellation called “star QAM”. The study starts of by assessing the performance results of an 8PSK star system carried out by computer simulation on a selective Rayleigh channel with different spread delay values, for an ICOFDM system, using BCH block code (127, 106, 3)