| 摘要 |
PURPOSE:To realize a code multiplex, by giving a delay to a pseudo noise code, which modulates two carriers, by means of a transmitter, and correcting the delay by means of a receiver to change the amount of delay. CONSTITUTION:At a transmitter, a pseudo noise (PN) code, which modulates the carrier of frequency f2, is delayed by n bits by delay elements 21 and 22 and supplied to a balanced modulator 4. On the other hand, the carrier of frequency f1 is modulated 3 by a signal added 1 by the PN code and transmission data, and the two carriers are coupled by a directional coupler 7 to be sent from a transmission antenna 8. At a receiver, spread spectrum (SS) modulation waves of the central frequencies f1 and f2 are picked up by BPFs 10 and 11 and converted to IF signals by frequency mixers 25 and 26. At this stage, the IF signal modulated by the PN code, which is not delayed by the transmitter, is inputted to delay elements 23 and 24 to give them the same delay as those of elements 21 and 22 so that the PN codes in the two IF signals are attained to the same phase. These signals are correlated by a balanced modulator 12 to modulate 13 them. |
