| dc.description.abstract | Introduction: Omega navigation has great potential as a navigation sensor for general aviation aircraft. Advantages of Omega navigation include signal availability at all altitudes, and no need for overflying of various stations. Also, because Omega coverage is not localized to small geographic areas, area navigation is an implicit capability of airborne Omega receivers. For use in the National Airspace System, several questions arise: How accurate is Omega navigation? How do you use the measurements made to give navigation information? What are the noise sources? How can these noise sources be eliminated or minimized? How do you use Omega in the National Airspace System? This thesis attempts to answer these questions based upon a 70-hour flight test program, mathematical models, analysis of the literature, and the author's experience as a commercially licensed, instrument-rated pilot. The thesis rather naturally divides into two parts: the first, Chapters II through VIII, attempts to answer the questions of Omega accuracy and operational characteristics. The second part of the thesis, Chapters IX through XVI, considers the questions of Omega implementation, including regulatory aspects and details required by good operating practice. The first part of the thesis, Chapters II through VIII, concerns Omega accuracies and the results of a 70-hour flight test program. Omega noise sources discussed in the literature were used for mathematical models, and a noise source not considered in the literature is discussed and measured. This is "short-term Omega noise", which is the noise in phase between successive measurements. For long time constant receivers, this noise is not important, but for light aircraft navigation, this is an important noise source. Analysis of the Weibull distribution showed little applicability of this distribution to Omega navigation errors, based upon the experience acquired in this program with a low-cost, commercially available Omega receiver. This flight test is also discussed in Refs. 16 and 17. In addition, four approaches were flown using Omega navigation, with surprisingly good results. Based upon the flight test data and the short-term noise measurements, mathematical models were made to determine RMS error of differential Omega with variations in update rate, and path-following accuracies available using Omega. The second part of the thesis concerns Omega implementation. The various configurations of Omega receivers are discussed. These configurations differ in what information is processed and how this information is used to give position information. Present regulations for Omega receivers are discussed, and future requirements for airborne Omega receivers, such as self-test and fail-soft capabilities, are discussed. Problems of waypoint setting errors with area navigation systems are discussed, and an easy method of error detection is shown which is compatible with Omega way point definition and which will allow use of standard aeronautical charts with minimal changes. Differential Omega is discussed in terms of message content and uplink medium. The results of the thesis are boiled down into the last chapter, the Conclusions. All of the meaty points are discussed briefly. Appendices include data on the approaches flown with the Omega receiver; the data collection and reduction for the flight evaluation program; and copyright agreement restrictions on reproduction of certain figures in the thesis based upon copyrighted approach plates. | en_US |
