24- and 120-Channel Transmultiplexers Built with New Digital Signal Processing LSI's

Two new digital transmultiplexers intended for commercial use have been developed. One transmultiplexer performs a bilateral conversion between two 12-channel FDM group signals and a 24-channel PCM carrier signal. The other mutually connects two 60Channel FDM supergroup signals and five 24-channel or four 30channel PCM signals. Both exploit a block processing digital SSBFDM multiplex/demultiplex scheme employing a cascade of an FFT processor and a set of complex coefficient digital filters. They have been built using newly developed high-level DSP LSI chips. Algorithmic considerations, developed LSI architecture, and equipment configuration are described as well as digital processor design details and measured performance.