Sideways looking radar for aircraft

摘要

The radar includes a device for continuously comparing the amplitudes of components of a received signal whose Doppler frequencies are predetermined different values. The different values may be positive and negative respectively. The values can be equal positive and negative values. The values are preferably chosen having regard to the aircraft speed and the antenna characteristics. The comparison can be effected by passing the received signal through two filters (6,7) having predetermined passbands and comparing their outputs after delaying (8) one by a predetermined delay.