Block Coded Combined Shannon-Fano and GAC Codes Employing Phase/Frequency Modulation
In this paper, a combined technique for source coding, channel coding and modulation is proposed. This technique employs Shannon-Fano code for source coding, Generalized Array Codes (GAC) for channel coding and Phase/Frequency (BFSK/MPSK) for modulation. The combined scheme has the advantage of reducing the redundancy, providing error control and simultaneously optimising on channel bandwidth over the separate one. The algorithm used to construct any combined trellis decoder of Shannon-Fano and GAC codes employing phase/frequency modulation from a given source text file is designed and implemented in software. The error performances for the combined schemes using BFSK/MPSK modulation are compared with those employing coded as well as uncoded MPSK modulation. It is shown that the combined system gives the same performance as its separate counterparts but has lower complexity. Such a Block Coded combined Shannon-Fano and GAC code employing BFSK/MPSK modulation scheme can find suitable applications in magnetic and optical storage devices as well as in data transmission systems.
Keywords: source coding, combined coding and modulation.