The CAA Doppler Omnirange

This paper describes a VHF omnirange, the operation of which is based upon an application of the Doppler effect. Progress in the development of a Doppler VOR is outlined. The Doppler VOR has a measured 7-to-1 improvement with respect to siting effects when compared to the conventional four-loop VHF omnirange. The wave transmitted by the Doppler VOR is horizontally polarized. The unique interchange in the functions of the 30-cps amplitude modulation and the 30-cps frequency modulation of a 9.96-kc subcarrier is described. The Doppler VOR is shown to be compatible with present VHF omnirange receiving equipment. The results reported in this paper were obtained by experimentation and mathematical analysis.