PURPOSE: To match automatically the phase defference of the signal of a slave station basing on a receive signal from a main station by converting the phase difference into a digital signal and storing it, and using the stored signal as a control signal to control a matching means.

CONSTITUTION: A multipluse frequency (e) transmitted from the main station is received by a 5-wave decca receiver 1. The receiver 1 outputs an intermediate frequency (a) used as a phase reference and a frequency (b) one-fifth as high as the frequency (a) from the five received waves. Phase difference signals outputted from phase discriminators 2 and 3 drive phase display devices 4 and 5 and are inputted to and converted into digital signals by digitizers 21 and 22. The output of the digitizer 21 is inputted to a storage part 31, which outputs a control signal corresponding to the input signal. Then, an automatic control circuit 41 drives a phase adjusting circuit to input a basic wave for eliminating the phase difference automatically to a transmission part.