电信和无线电工程

ELEVATION ANGLE MEASUREMENT ABOVE THE SEA SURFACE USING THE ROOT-MUSIC METHOD. SELECTION OF SOLUTIONS

ABSTRACT

In this paper special emphasis is given to improving the accuracy of elevation angle measurement of law-altitude targets above the sea through the use of the root-Music method. To this end, this special-purpose technique (or a sort of algorithm) is used, which is treated by some experts as the one helping solve this particular problem. The method in hand cannot be effectively implemented unless one of the issues pertinent to selecting a target-related solution is adequately explored. The appropriate solutions are chosen from the collection of several solutions already found. Their number is determined by the subspace dimension of signals. It is through computer simulation process that the collection of measured elevation angle distributions were obtained and analyzed for sea states. This procedure was accomplished at a varying number of spatial signal samples on a given antenna array aperture and with different subspace dimensions of signals. Elevation angle dependences of r.m.s. elevation-angle measurement errors are calculated using several proposed rules of solution choice. Special requirements are set for antenna arrays used in elevation angle measuring devices. The requirements, if properly used, will lead to a decrease in solution error. We have come up with the rules that find effective solution to an adequate choice of a definite problem. The findings of the studies five a good indication of how to refine the techniques for and devices of measuring the elevation angles of low-altitude targets above the sea.