| 摘要 |
PURPOSE:To improve the loop synchronization in an SS loop transmission system which receives and transmits a desired signal, by using a spectrum scattering (SS) modulation/demodulation method for a plurality of subscriber terminals dotted on a loop transmission line. CONSTITUTION:Before the start of data transmission/reception between subscriber terminals 12-18, first a virtual noise series having predetermined frame period as a synchronizing signal from a synchronizing terminal 11 is transmitted to a loop transmission line 10. The terminal 11 detects the frame phase defference between the transmitted virtual noise series and that returned through circulation, and the loop synchronization can be established by controlling the phase of a virtual noise generating clock so that the frame phase difference is zero. After subscriber terminals 12-18 are elapsed for the time for loop synchronization a signal inputted from the loop transmission line 10 detects the synchronous virtual noise series and discriminates the frame reference time, generates the SS modulation/demodulation virtual noise series in frame synchronization and this is used as SS modulation/demodulation carrier. |
