Automatic Star-Trackers for Long-Range Navigation

Abstract

This paper describes development trends of one particular navigational technique (automatic star tracking) and its associated instrumentation methods one of which, the application of pulse code modulation theory to sensor design, is discussed in detail. Plans for the future development of this most promising concept are also included and the effects of military research and development efforts on civilian aircraft requirements are indicated. An appendix provides a glossary of special terms used.Automatic star-tracking systems have been used in military aircraft navigation for position fixing and heading correction for a number of years and the development of the equipment has been actively pursued by the U.S.A.F. since as early as 1946. Basically, star trackers are automatic devices that probe a portion of the celestial sphere for the purpose of detecting, acquiring and tracking stars or other celestial bodies. In using astronomical inputs for cruise vehicle navigation, advantage is taken of the well-known principle that sights on two or more stars when referred to the true vertical and time can be used to provide a position fix. It is the intent of this paper to review techniques used to instrument star trackers, discuss their application to long-range aircraft navigation, indicate development trends and introduce a new concept of employing pulse code modulation theory to the design of a simple, low cost automatic astro-tracker.