Bandwidth compression with periodically time-varying FIR filters

A bandwidth compression(expansion) system has been developed for transmission of wide band signals over narrow band channels. The system is based on a linear periodically time-varying(PTV) FIR structure. The coefficients are chosen to approximate an ideal bandwidth compressor(expander). The distorting components of the cascaded system(compressor-expander) can be precisely described using the bifrequency system function.