Image Number 2 for United States Patent #5036325.
A doppler determination system uses an amplitude comparison of odd and even MTI functions derived from the same signal returns in an MTI radar system to determine the doppler frequency of a target return. The system determines the ratio of the amplitudes of the return of a single canceller circuit with a delay of 2/PRF and the amplitude of the return of a double canceller with two delays of 1/PRF. The ratio is then employed to estimate the doppler frequency of the return. The respective amplitudes of the two MTI circuits are also processed in a 3-dimensional radar application to provide estimates of the target radar cross-section and elevation angle, and with PRF switching to determine the target unambiguous range rate.