Acoustic echo sounders have recently come into their own as valuable remote sensors for determining atmospheric structures and winds. Kelton and Bricout [Bull. Am. Meteor. Soc.45, 571–580 (1964)] first demonstrated that the acoustic Doppler shifted signals from scattered sound were related to the ambient winds. Later, McAllister [J. Atmos. Terr. Phys.30, 1439–1440 (1968)] showed that a vertically pointing monostatic acoustic sounder could reveal, in intricate detail, the atmospheric boundary layer structure. An acoustic echo sounder and wind sensor system capable of simultaneously measuring temperature fluctuations in the lower atmosphere and the vertical profile of wind speed and direction has been in operation at the Naval Electronics Laboratory Center since 1973. It is the purpose of this paper to describe the capability of this acoustic echo and wind sensor system for determining atmospheric structure and winds.