PURPOSE: To make the detection of propagation distortion easy, by applying the receiver to a space diversity receiving system of a multivalue digital microwave communication system with good transmission efficiency.

CONSTITUTION: Two signals having some frequency shifts are synthesized at a synthesis circuit 5. An intermediate frequency signal 7 zeroes the absolute delay time difference in existing between two signal transmission lines with an insulation delay time differential equalizer 10. Thus, even if a fading in 0dB∼40dB is produced, the two signals on intermediate frequency output signals 11a∼11b have almost the same level and phase. Next, although the output signals are subjected to propagation distortion when the selective fading is produced, an IF synthesizing device is controlled so that smaller propagation distortion can be selected without hit.