A comprehensive survey of digital transmultiplexing methods

With this survey, an attempt is made to describe the great majority of all known methods of digital transmultiplexing (i.e., conversion) of time-division-multiplex (TDM) to frequency-division-multiplex (FDM) signals, and vice versa. To this end, the individual transmultiplexer approaches are classified into four categories according to the underlying algorithm: Bandpass filter bank, low-pass filter bank, Weaver structure method, and multistage modulation method. Finally, the overall performance of the various transmultiplexer approaches are compared with each other by means of different criteria [1], such as stability under looped conditions, absolute value of the group delay, computational and control complexity, modularity, potential of intelligible crosstalk, absence of an additional analog frequency conversion, and the impact of out-of-band signaling For a more profound understanding of the individual digital trsnsmultiplexer approaches, the main chapter is preceded by an introductory discussion on analog and digital generation of single-sideband signals. In this context, the associated problems of sample rate alteration and multi-rate filtering arising from digital signal processing are dealt with.