| 摘要 |
PROBLEM TO BE SOLVED: To reduce the variation width of detected signal levels less than a specific value even in the case of using a simple signal level detection circuit by providing the transmitting device with a modulation circuit for fixing the directions of reference axes of carriers belonging to each group on, a specific direction and modulating respective carriers. SOLUTION: Carriers of orthogonal frequency division multiplex modulation (OFDM) type signals to be transmitted are divided into plural groups>= two groups, the directions of reference axes of carriers belonging to each group are fixed on a specific direction in which the signal points of the carriers in each group are not superposed to each other and a quadrature shift keying (QPSK) modulation circuit 1 modulates respective carriers by using the set reference axis direction, multiplexes these modulated carriers and transmits the multiplexed carrier. Even when a simple signal level detection circuit capable of reducing its circuit scale is used as a signal level detection circuit for controlling AGC circuit, the variation width of signal levels generated due to the calculation error of detected signal levels can be suppressed to about 1 dB to be an allowable limit.
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