| 摘要 |
PURPOSE:To execute the SCPC(Single Channel Per Carrier) transmission of a high quality by constituting the device so that a diffusion modulation and a reverse diffusion modulation are executed before and after an intermediate frequency(IF) signal is converted to an RF signal by a frequency converting means. CONSTITUTION:An IF signal 27 has a spectrum of band width (bi) centering around a frequency fIF, and this IF signal 27 is supplied to a diffusion modulator 26, and diffused to an IF signal 28 having the spectrum of band width Bi. The IF signal 28 of band width Bi centering around the frequency fIF is further supplied to a frequency converting mixer 29, and converted to a signal 32 of an RF frequency therein. In this case, an additive noise 42 of band width (bn) is generated, added to the signal 32, this signal 32 is supplied to a reverse diffusion modulator 37, brought to reverse diffusion, and the signal 38 brought to reverse diffusion returns to an information band (bi) before being diffused by the diffusion modulator 26. On the other hand, the additive noise 42 is diffused to a band Bn, and a spectrum of the additive noise in the information band (bi) is improved to bn/Bi, that is bn/Bn. In such a way, the SCPC transmission of a high quality can be executed. |
