Digital Tracking Loop for High-Powered, Experimental Radar

摘要

The problem of utilizing a digital computer as one element of a radar system for tracking of space objects, such as satellites, is investigated. The basic principle of curve extrapolation for digital tracking is mentioned and the fitting of either a first or second order curve to three points is developed. The facilities of the Millstone Radar site are described in detail, with emphasis on the role each component plays as an element of a closed-loop tracking system. For the purposes of comparison, a brief analysis of the operation of the present analog tracking system is presented. A computer program for the digital computer is written and each phase of the program explained in detail. The emphasis is on logical methods and techniques for tracking rather than on arithmetic operations. The system is tested with simulated and real time data. The arithmetic and logical tests indicated perfect operation of the program. Testing with taped data showed the presence of a noise problem. In actual operation, the linear extrapolation produced satisfactory tracking, whereas the second order extrapolation was unstable due to pulse-to-pulse noise. A method is developed for measuring the mean square tracking error of either the analog or digital tracking system using tape-recorded error signals and an analog computer. The ratio of the value obtained for the digital tracker to that for the analog system is 1.12. (Author)