Modulation and multiplexing system for telephone signal transmission - converts signals into digital words which are combined by fourier transformation to analogue data for transmission

摘要

Telephone signals are coded by pulse code multiplexing and are memorised frame by frame in a memory for application via gates to an inverse Fourier transformation circuit. The circuit comprises a register and a ROM with a calculator to perform the transformation. The transformed output is applied in serial or parallel data streams via gates and a serial circuit to a decoder to provide amplitude modulated pulses for transmission to a receiver. A clock system provides sync. pulses for the coding and decoding processes. To each sinusoidal signal created, a constant phase constant is as assigned. The phase constant is chosen among four predetermined angular valves such as to represent a doublet. The angular valves are odd multiples of 45 degrees.