| 摘要 |
PURPOSE:To effectively use the dynamic range of a D/A converter by decreasing a data width of a digital modulation signal when a signal of an OFDM system is sent. CONSTITUTION:An I signal received from an I signal input terminal 1 is converted into a modulation signal by an S/P converter 3, a discrete inverse Fourier transformation device 5, and a P/S converter 6 and the converted signal is fed to an amplitude control circuit 9. When the amplitude of the modulation signal exceeds a threshold level, an amplitude control circuit 8 sets the amplitude to be a prescribed upper limit value. A Q signal received from a Q signal input terminal 2 is processed similarly to the case of the I signal at an S/P converter 4, the discrete inverse Fourier transformation device 5, a P/S converter 7 and the amplitude control circuit 9. The modulation signal obtained by an amplitude control circuit 8 or 9 is converted into an analog modulation signal at a D/A converter 10 or 11. |
