An external meteor detection system for the middle and upper atmosphere (MU) radar, Shigaraki, Japan, has been developed in order to monitor the wind velocities at 80--100 km. The characteristics of the MU radar system and the observations are closely inspected, and we design a three-channel interferometer system using three independent single antennas. The data-taking system was carefully designed, considering fast data rate, short interpulse period, wide data bits (19 bit), and fast sampling rate (1 million samples/s), and all the logics are assembled by programmable logic devices. This external interferometer was operated since March 1995 during the Doppler beam swinging observation by the MU radar, and the first results are presented. Meteor echo rate was around 2000/day, 1000 of which were usable for postprocessing, i.e., wind measurement. This echo rate is greater than that of the meteor radar system in Jakarta. Wind velocities were determined with time-height resolutions of 1 hour¿2 km, which showed reasonable agreement with the wind velocities determined from the turbulent echoes in the mesosphere. We present the capability of an external interferometry system attached to the mesosphere-stratosphere-troposphere/stratosphere-troposphere radar as a meteor wind observation system.¿ 1997 American Geophysical Union