A simplified acoustic Doppler wind sensor that can be built around an existing sounder is described. The instrument consists of two fan-beam transmitters and a pencil-beam receiver in an orthogonal configuration. Considerable improvement in signal-to-noise ratio over previous techniques is realized with this approach. Field tests show good agreement between the Doppler sounder measurements and wind measurements with in situ sensors on a 150 m tower. The system operated satisfactorily in an airport environment under fog conditions as well as in light rain. It failed only during periods of jet aircraft activity directly over the sounder and under conditions of moderate-to-heavy rainfall.