| 摘要 |
PURPOSE:To use a modulating circuit for a desired number of multiple values in common by forming a cosine roll-off waveform by a digital signal processing circuit corresponding to a binary input digital signal and performing the addition processing corresponding to a multiple level number setting signal by an adding circuit. CONSTITUTION:Digital signal processing circuits 1 subject the input digital signal to the cosine roll-off waveform formation and set the number of multiple values by the mulitivalued number set signal. In the case of four values. the output signal of one digital signal processing circuit 1 is selected in each adding circuit 2 and is applied to a DA converter 3 through a correction processing part 5, and a converted analog signal is applied to an orthogonal modulator 4 and is orthogonally modulated. In the case of 16 values, one of output signals of two digital signal processing circuits 1 is multiplied by 1/2 and both output signals are added by each adding circuit 2. In the case of 64 levels, first and second output signals out of output signals of three digital signal processing circuits 1 are multiplied by 1/2 and 1/4 and these three output signals are added by each adding circuit 2 to output the addition signal. |
