An improved pulse technique which permits simultaneous observation of time delay and elevation angle of arrival of ionospheric echoes has enabled recognition of seven different modes of backscatter propagation involving both ionospheric and ground origins. By the use of four transmitting aerials with differing directional characteristics, it is shown that land is a more prominent source of backscatter than sea at low angles of elevation and that extremely large changes in land roughness can be identified by the resultant increase of backscatter echo amplitude.