| 摘要 |
<P>PROBLEM TO BE SOLVED: To transmit a sub-signal such as a monitoring signal without deteriorating transmission characteristics of a main signal and without reducing transmission efficiency. <P>SOLUTION: The main signal is transmitted while switching a plurality of modulation modes with almost equal transmission characteristics, and the modulation modes are switched according to the sub-signal. For example, QAM modulation is used for modulation, a code whose amplification ratio between an i axis component and a q axis component of the QAM modulation is 1:√3 is used, amplitude of the i axis component and the q axis component are replaced by the sub-signal to transmit the sub-signal by amplitude components of the i axis component and the q axis component. Or, QAM modulation using the code whose amplification ratio between the i axis component and the q axis component is 1:√3, and QPSK modulation in which amplitude of the i axis component and the q axis component are equal to each other and having amplitude of √2 when it is standardized by the amplitude of the code are used for modulation, the two modulation modes are switched by the sub-signal to transmit the sub-signal by the amplitude components of the i axis component and the q axis component. <P>COPYRIGHT: (C)2009,JPO&INPIT |
