Radar tracking of seaskimmers. Report from field trials with the CHASE algorithm

A method for reducing the effects of multipath in radar tracking at sea by CHASE (CelsiusTech High Accuracy Seaskimmer Estimator) has earlier been described by Eckersten and As (1992) together with preliminary test results. The principle is an extension of the "complex angle" method, described by Sherman (1971), and uses the particular properties of the CelsiusTech CEROS tracking radar. The method has been investigated theoretically and by simulations, all indicating very promising results. Extensive trials were carried out during the autumn of 1994 for a number of sea-states and target altitudes, including seaskimming runs down to 6 m above the sea surface. Evaluations with a slightly modified algorithm verifies the accuracy of the method for all tested target altitudes and sea-states. This paper describes the method used and discuss the results obtained.