We have been studying an advanced satellite broadcasting system which is aimed at improving the Integrated Services Digital Broadcasting for Satellite (ISDB-S) system. By making use of LDPC codes and the reduced roll-off factor, this advanced system can increase its transmission channel capacity to 30% that of the ISDB-S one. Furthermore, by applying multi-level amplitude phase shift keying (M-APSK) modulation schemes, we can increase the transmission channel capacity. We report on LDPC codes that are designed for the transmission format of the advanced satellite broadcasting system. The computer simulation results of B/Q/8PSK performances under the AWGN channel model are also reported. We also discuss and report the optimization result gained from a computer simulation of the radius ratio of LDPC-coded 16APSK and 32APSK modulation, which is proposed in this advanced system, with respect to Bit Error Rate (BER) under the AWGN channel model.