| 摘要 |
PURPOSE:To avoid a state that the communication function of a whole system is lost by providing a present control earth station and a standby control earth station, both of which can centrally assign and control a communication channel through the use of the same common signal channel. CONSTITUTION:When a main DAMA(Demand-Assigned Multiple Access) controller 11 in the control earth station 1 detects that an abnormality occurs in a self DAMA centralized control function, it stops the action of a MODEM for CSC(common signal channel) 12. As a result, a main DAMA controller 11 in the control earth station 2 detects that the signal of a continuous mode from CSC is eliminated, starts the MODEM for CSC 12 after a prescribed time lapses and transmits the signal of the continuous mode to CSC. Next, it attains DAMA centralized control in place of DAMA controller 11 in the control earth station 1. Since the main DAMA controller 11 is substituted, the carrier frequency of CSC does not change and therefore, respective slave DAMA controllers 14 do not need to execute special processings with respect to the substitution. |
