Patent ID: 7961813

Claim:
A multi-value modulation/demodulation method, comprising the following steps: generating N quaternary phase shift keying (QPSK) outputs having different amplitude levels r2=r1×2 −(i−1) , i=2 . . . N with respect to a maximum amplitude level r1 to form M(=2 2N )-valued/quadrature amplitude modulation (QAM); power amplifying powers of N-1 outputs si from respective executions of quaternary phase shift keying QPSK-i (i=2 to n) except the quaternary phase shift keying QPSK- 1 having the maximum amplitude r1 at the time of the formation; performing a combination by using a directional coupler having N-1 input terminals and one output terminal to obtain a combined signal after power amplification; transmitting an output of the quaternary phase shift keying QPSK- 1 and the combined signal from two systems of antennas; and vectorially superposing and combining the transmitted signals in a space.