A minimum-phase FIR complex filter design for transmultiplexer implementation

A digital per-channel transmultiplexer system, based on the generation of a baseband analytic signal and on its successive interpolation and filtering, is considered. The method employs complex filters. To meet the CCITT specifications on the conversion system group delay, minimum-phase FIR complex filters are required. Their design is described in this paper. The system design also includes the evaluation of the wordlengths of the filter coefficients and the arithmetic operations. Computer simulations show that a 16 bit arithmetics is suitable throughout the whole conversion system. These characteristics suggest convenient hard-ware implementations with low-cost arithmetic circuits.