| 摘要 |
<p>PURPOSE:To highly accurately detect the direction of a target in the wide range of angles with a limited number of antennas by providing a plurality of antennas, a transmitting part, a receiving part and a direction detecting means. CONSTITUTION:A beat signal is generated in each mixer circuit while each of FM waves distributed to two adjacent antennas overlaps with a locally generated wave. When a target is within a point-blank range, the FM waves TXa-TXd can be regarded as receiving/reflecting waves RXa-RXd. Therefore, mixer circuits 43a-43d generate beat signals BTa-BTd while the FM waves TXa-TXd overlap with the locally generated waves LOa-LOd. A CPU 51 statistically processes frequencies of seven beat signals and determines the beat frequency, based on which the propagation delay time of the FM waves is calculated thereby to calculate the distance to the target. The direction to the target is detected by selecting from the seven beat signals and calculating the average value of the directional angle of the corresponding antenna while weighting at each selected level.</p> |
