| 摘要 |
PURPOSE:To utilize a valuable frequency resource by using both an FDM (frequency- division multiplex) communication system and a CDM (code-division multiplex) communication system together. CONSTITUTION:Small-sized earth stations 20-1-20-K and 40-2-40-K perform transmission to and reception from a base station 30 with assigned frequency slots by using a FDM signal. The base station 30, on the other hand, sends out a time reference at a constant period with a CMD signal. A moving body, on the other hand, has a comb-shaped filter bank which has a 1st channel as a stopping area and a 2nd channel as a passing area, so its filtering characteristics generate the CDM signal covering band width separately from the FDM signal, so that the CDM signal of narrow width of one frequency slot is outputted to a matching filter with every other frequency slot. Further, a spread spectrum modulator 11 processes the output of a data modulator 10 with a PN code synchronized with a regenerated PN clock. Further, the outputs of comb-shaped filter banks 30-1 and 30-2 are diffused reversely by matching filters 7-1 and 7-2, inputted to CDM demodulators 31-1-31-2, and inputted to a position measurement calculation part 8, so that the position measurement data are sent to the moving body. |
