Transmitter and receiver for an orthogonally multiplexed qam signal of a sampling rate n times that of pam signals, comprising an n/2-point offset fourier transform processor

Abstract From the Canadian patent

In a transmitter for digitally converting PAM signals 2L in number, of a common slow sampling rate of 1/T hertzes to an orthogonally multiplexed QAM signal of a fast sampling rate of N/T hertzes, N/2-point input data into which the PAM signals are pre-processed with addition thereto of dummy signals only, (N/2 - L) in number, are supplied to at least one N/2-point ODFT (offset discrete Fourier transform) processor (61) a pair of, which (61, 62) must have been an N-point OFDT processor accompanied by switches controlled at a T/2-second period. After caused to pass through respective filter units of a bank (71). N/2-point output data are time-division multiplexed into the QAM signal. The …