Abstract: The secant compensation method for correcting an angular deviation of radar tracking measurement system in azimuth-elevation polar coordinate frame is reviewed, and its pros and cons are analyzed. To overcome the complexity of derivation process and singularity, a tracking pointing coordinate system, i.e., line-of-sight coordinate system, and a simple and practical nonsingularity compensation method based on coordinate transform principle are proposed. The equipollency between the proposed method and the universal secant compensation method based on solid geometry reasoning results is proven. The application of the proposed method in typical deviation correction of shafting and its effect on the tracking and measurement accuracies of radar system are also analyzed. For elevation angle of 89°, and azimuth and elevation angular deviations of 3 mrad, the azimuth error and elevation error calculated by the secant compensation method are 6 759.2″and 63.5″, respectively. The proposed method is benefit for the high precision tracking and measurement of space targets in the polar coordinate frame, especially to effectively improve the zenith tracking performance and the pointing accuracy with high elevation.

Key words: radar engineering, tracking and measurement, polar coordinate frame, deviation correction, secant compensation