Wide-Aperture Digital VOR
The very high frequency (VHF) omnirange has undergone a number of evolutionary changes in the past 30 years. Early measurements of large errors led to the development of the Doppler VHF omnidirectional irectioal range (VOR) and its use. Further developments have been the precision multilobe VOR and the precision Doppler VOR. Interest in area navigation has led to the desire for a VOR greatly superior to any so far developed. Specifically, the objectives of the improved VOR would be a system that would significantly reduce magnitude of siting errors, provide greater accuracy and use digital techniques to simplify processing. ssing. The wide-aperture digital VOR described herein has been developed to meet these objectives. Its design is based on the crossed-pair interferometer principle where eight such pairs are energized successively by a set of pulses and phase shifts. The time multiplexed signal, detected by the aircraft receiver, is processed and simple digital computations are performedto determine the angular coordinates. The performance improvements have been achieved by the combination of using a 275-ft antenna aperture, and the use of digital techniques to generate the ground-radiated navigational signals and to process them in the airborne processor. Field tests of the feasibility model indicate it is a high performance ance system, capable of achieving an order of magnitude improvement in both site error reduction and in accuracy compared to present VOR systems. The measured accuracies were 0.11-degree standard deviation.
The Civil Aeronautics Administration VHF Omnirange
This report describes the development of a vhf-omnirange system, operating in the frequency band of 112 and 118 mc. The range furnishes magnetic-bearing information with respect to the range station, and provides definite track guidance between the station and any point within its service area. The omnirange produces two 30-cps signals: one is constant in phase and independent of the aircraft's position, and the other varies in relative phase directly in accordance with the magnetic bearing of the aircraft from the station. A phase-measuring device in the receiver enables the pilot to determine his magnetic bearing with respect to the station, and to select and fly a range course on any desired magnetic bearing. The accuracy of the system, including the receiver plus ground equipment, in operation at the Civil Aeronautics Administration Experimental Station, Indianapolis, Indiana, is approximately 1.5 degrees. The ground equipment has been in continuous operation for more than 3 years. The vhf omnirange has been selected as part of the common Civil-Military System, Transition Program, as recommended by the Radio Technical Commission for Aeronautics.
Analysis of a coaxial-to-waveguide adaptor including a discended probe and a tuning post
A field matching analysis of a coaxial-to-waveguide adaptor incorporating a disc-ended probe and a tuning post is presented. In this analysis, the tuning post is considered as a short-circuited second probe. A computer algorithm for calculating the input impedance of this structure is developed. This algorithm is used to investigate and improve the operation of a commercially available coaxial-to-waveguide adaptor. >