A Study on the Distortion of Course Information due to Wheel-shaped Barbed-wires Fences

Abstract

The very high frequency(VHF) Omnirange is used as an aircraft navigational aid. The VHF Omnirange is a short-range air navigation system providing aircraft with its bearing relative to the ground station. The VHF Omnirange has undergone a number of evolutionary changes in the past 60 years. The objectives of the improved VHF Omnirange would be a system that would significantly reduce the magnitude of bearing errors, provide greater accuracy and use digital techniques to improve the system. The VHF Omnirange signal in space is a composite of the direct and scattered carrier plus sideband and identification signals. The receiver antenna is designed to pick up only the horizontally polarized component of the electric field available at the antenna. The bearing errors caused by the obstacles have been examined by Anderson, Gruenberg and Yamamoto. This paper quoted the research with the principle theory such as mathematical analysis regarding scalloping errors. The objective of this paper is to derive an analysis method for quantitative prediction of the distortion of course information due to the wheel-shaped wires. The main emphasis is the error caused by the scattered signal at actual site. Course scalloping is a periodic variation of the indicated bearing about the correct azimuth, where the frequency varies with position in space. The results reported in this paper were obtained by mathematical analysis, computer-based simulations and experimentation.