To simply obtain the radio propagation characteristic of frequency spread communication based on an amplitude and a ripple component of a demodulated waveform by generating a carrier using a frequency interval of frequency spread as its period, amplitude-modulating the carrier with 20T pulses and using the amplitude-modulated carrier to apply amplitude- modulation to a center frequency of spread communication.

A generator 14 generates a 1st carrier f1 using a frequency interval of spread communication as its period. A timing generator 11 and a square pulse generator 12 generate pulses (20T pulses) using ten times of the period corresponding to the frequency interval of spread communication as a half value width and a modulator 15 applies amplitude modulation to the f1. A mixer 16 mixes the amplitude modulation output and the 20T pulses to obtain only a positive waveform. A 2nd carrier generator 18 generates a center frequency f0 of the spread communication, a modulator 17 amplitude-modulates a 2nd carrier f0 with an output waveform of the mixer 16 and sends the resulting modulation signal via an amplifier 19 and an antenna 20. A receiver demodulates a signal obtained via an antenna 30 and an amplifier 31 with an output of a local oscillator 33 having the same frequency f0 as the 2nd carrier. Based on an amplitude D0 of a demodulated output waveform and a ripple component (d), a numeral in correlation with the propagation characteristic is calculated.