PURPOSE: To exclude reception waves provided with propagation delay larger than the detection accuracy of a phase comparison means for detecting a time division multiple access frame phase difference from the input of a mutual synchronization means.

CONSTITUTION: Time division multiple access frame phase difference signals for the past (k) times are stored in a history storage means 102-i. When the time division multiple access frame phase difference signal is received, a delay wave detection means 101-i stores it in a register Reg i(0) inside the history storage means 102-i and a delay wave judgement means 103-i checks values held in the registers Reg i(0) to Reg i(-k) of (k+1) stages inside the history storage means 102-i. When all the values of the registers inside the history storage means 102-i are the same value different from '0', the delay wave judgement means 103-i outputs a base station identification number (i).