| 摘要 |
PURPOSE:To obtain a carrier wave with excellent S/N by multiplying the frequency of reception wave of an auxiliary signal by two in an MSK modulation system to attain the regeneration of carrier wave thereby reducing the reception of effect of a transmission line on the way. CONSTITUTION:A signal MODout to be modulated transmitted from a transmission system 100 is transmitted to a reception system 200 through a transmission line 150, and an input DEMin being a demodulator input DEMin is divided into two by a branching device 208; one DEMin1 is fed to demodulators 202, 203 for a main signal through a distributor 207, and the other input DEMin2 is FM-demodulated by a discriminator 204 being a demodulator for an auxiliary signal and an auxiliary signal SCout is outputted. Further, the DEMin2 is multiplied by two at a frequency multiplier 201. Since the carrier frequency at the center is regenerated when being multiplied by two as a characteristic of an MSK signal with a phase modulation index of 0.5, a carrier frequency fc is regenerated from the frequency multiplier 201. One of the regenerated carriers CR' is fed to a synchronism detector 202 as it is and the other is fed to a synchronism detector 203 while being shifted for the phase by pi/2, and PCM outputs Iout and Qout of the main signal are demodulated and outputted respectively. |
