ディジタルPLL方式VOR信号処理装置

Abstract

VOR (VHF omnidirectional radio range) is a short-range air navigation assistance facility of international standard providing directional information. The bearing of VOR is measured by the phase difference of two 30-Hz sine waves, reference and variable phase signals. Recently, the bearing accuracy of VOR receiver has been made great improvement using a digital signal processing technique in place of an analog processing one. However, the bearing stability of a digital signal processor with zero cross detection method is not good when the receiving signal level is low or the distortion of detected signal is large. In order to eliminate these defects, it is worked out a new VOR signal processor using a digital phase lock technique. It is replaced the reference and variable signals with two square waves which synchronize to these signals. The experiment results of the new VOR signal processor are as follows. The bearing accuracy is less than 0.1°and the bearing fluctuation is less than 0.2°at the level of the minimum receiving sensitivity (-90 dBm).