The azimuth detection part is provided with means (SMPL1, SMPL2, CMPX1, CMPX2) which sample the received signals, which create a complex signal on the basis of a pair of most adjacent sampling values and which detect the phase difference between the received signals on the basis of the complex signal. そして、上記方位検出部は、各受信信号をサンプリングし、最隣接のサンプリング値の対から複素信号を作成し、この複素信号に基づき各受信信号の位相差を検出する手段(SMPL1,SMPL2,CMPX1,CMPX2) を備えている。 - 特許庁