PURPOSE: To allow especially a transmitter of a slave station to eliminate the need for a power amplifier of large power by allocating a frequency minimizing cross modulation product to the slave station at every call when DAMA processing is executed in a satellite communication network, etc., by the SCPC system.

CONSTITUTION: When a main circuit 4 allocates a frequency to a slave station, the circuit 4 reads the frequency being the result of calculation by a frequency calculation section 2 at preceding time where cross modulation product is not most superimposed from a slave station classified frequency storage use register 3 to make calling processing. A slave station classified transmission frequency table storage section 1 at the time end of talking fetches the frequency used for the talking from the slave station classified frequency storage use register 3 to revise the table, and thereafter the frequency calculation section 2 calculates the frequency in which the cross modulation product is not most superimposed by the frequency calculation section 2 again when the transmission frequency is allocated to the slave station based on the revised table and the calculation result information Sb is stored by the slave station classified frequency storage use register 3. The processing procedure is repeated to allocate the frequency in which the cross modulation product sent from the slave station is always minimized.