The EISCAT meteor-head method ? a review and recent observations

International audienceSince the very first meteor observations at EISCAT in December 1990, the experimental method has improved significantly. This is due to a better understanding of the phenomenon and a recent major upgrade of the EISCAT signal processing and data storage capabilities. Now the simultaneous spatial-time resolution is under 100 m-ms class. To illuminate the meteor target for as long as possible and simultaneously get as good altitude resolution as possible, various coding techniques have been used, such as Barker codes and random codes with extremely low side lobe effects. This paper presents some background and the current view of the meteor head echo process at EISCAT as well as the observations which support this view, such as altitude distributions, dual-frequency target sizes and vector velocities. It also presents some preliminary results from recent very high resolution tristatic observations