A Modular Approach to a Digital 60-Channel Transmultiplexer Using Directional Filters

A multistep transmultiplexer approach with a single-way modulation scheme applying minimum phase wave digital directional or transversal filter is proposed. Furthermore, the impact of signaling, pilots, and spectral shaping at the PCM end is investigated. The main merits of this approach are, at a moderate level of computational complexity, its absolute stability, the low basic group delay, and its modularity. Due to modularity, the central unit (the TDM/FDM and FDM/TDM translators) is composed of only three different filter types requiring neither DFT, FFT, or associated processors nor modulators. As a consequence, the new approach is suitable for LSI/VLSI integration with the potential of efficient testability.