A technique wherein the amplitudes and/or phases of the signals received in overlapping antenna lobes are compared to estimate the angle of arrival of the signal. The technique determines the angle of arrival of a single pulse, or reply, within an antenna beamwidth. The angle of arrival is determined by means of a processor using the replies received through the sum and difference patterns of the antenna.
ICAO (2004) doc. 9684 Manual of the Secondary Surveillance Radar (SSR) Systems
The monopulse technique is generally termed “monopulse direction finding”.