| 摘要 |
PURPOSE:To secure a selection of the modulating carrier to the n and n+1 times as much as conventional by adopting the 2-step modulation system to the 1st and 3rd supergroup translations, thus miniaturizing each filter. CONSTITUTION:Basic supergroup p of 312-552kHz receives modulation at 1st modilator 9 and via 1st carrier wave nci which is obtained by giving n multiplication to carrier ci through multiplication circuit 17. And only upper side band wave nci+p is selected through filter 10a to be sent to 2nd modulator 11, where the modulation is given to wave nic+p sent for filter 10 via 2nd carrier (n+1)ci to send out the modulated wave to filter 12. Thus only the lower side band is selected through filter 12 to feature the same frequency band as conventional owing to (n+1)ci- (nci+p)=ci-p. The demodulation is carried out via filters 13 and 16, demodulators 14 and 15, etc. As a result, the filter can be miniaturized, realizing a highly economical system comstitution. |
