The digital ionospheric sounder, or dynasonde, located at the British Antarctic Survey's research station at Halley, Antarctica, has recently been operated as an imaging Doppler interferometer (IDI). The implementation of this mode of operation does not require any changes to the system hardware but involves a specially written sounding configuration and newly designed data analysis software. Using four independent antennas and two receivers, the signals returned from mesospheric altitudes are range-gated and processed using Doppler sorting and spatial interferometry. A three-dimensional (3-D) image of the scattering locations can then be built up for a region stretching to over 30 degrees from the zenith. The sky map locations and Doppler velocities of the individual scattering points are used to fit a 3-D velocity vector representing the motion of the neutral wind in the mesosphere. In this paper the radar hardware, sounding configuration, and data processing are described, and the relative merits of the IDI technique as applied at Halley are discussed. The characteristics of the scattering points are outlined, and initial neutral wind measurements are presented.¿ 1997 American Geophysical Union