ABSTRACT
Subspace U j n is defined as closure space of func-
tion un( )t , while U j n2 as closure space of function
1 INTRODUCTION
Navigation radar is an important tool for vessels’ navigation and collision avoidance. With the development of science and technology, its function is greatly improved with much more superiority and practicability. However, navigation radar image is often affected by noise and clutter in the process of image collection, transmission and display, resulting in the phenomenon of low Signal-to-Noise Ratio (SNR) and less precision. The digital preprocessing of the radar image is the basis of target tracking, intelligent early-warning, thus is of vital significance.
