Abstract: A method and apparatus for eliminating multiple-time echoes from the output signal train of random PRF pulse Doppler radar system. A multiple-time echo is recognized by calculation of the absolute value of the difference between the last two phase pulses received in each range gate (bin). That absolute value is compared to the average of the preceding N absolute value. A multiple-time echo is present if the last absolute value is higher by a predetermined amount than the average of the preceding N absolute values. A logical switch provides automatic switching to substitute a previous phase pulse in a corresponding range gate when the phase pulse of a range gate is determined to be altered by presence of a multiple-time (non-coherent) echo signal.

Abstract: A radar system for transmitting pulsed circularly polarized wave, having two separate receiving channels corresponding to the two mutually orthogonal components of the received wave. Apparatus is included for detecting variations of phase between the two receiving channels and automatically adjusting amplitude and phase of at least one of the two channels in order to compensate for the depolarization effects of rain. For isolating rain return signals and bona fide target signals, the ordinary range gate of a tracking radar plus wide early and late gates are used, applicable to target and rain return signals, respectively.