IJIREEICE IJIREEICE ISSN (Online) 2321 – 2004 ISSN (Print) 2321 – 5526 International Journal of Innovative Research in Electrical, Electronics, Instrumentation and Control Engineering ISO 3297:2007 Certified Vol. 5, Issue 6, June 2017 Copyright to IJIREEICE DOI 10.17148/IJIREEICE.2017.5649 293 UGC Approved Journal A Novel Method for Very-high Frequency Omni Range (VOR) Azimuth Error Correction using Kalman Filter for the Improvement of Aircraft Density K. Ramakrishna 1 , M R K Murthy 2 , N S Murthy Sharma 3 Research Scholar, Dept of ECE, College of Engg., Osmania University, Hyderabad, India 1 Dept of ECE, College of Engg., Osmania University, Hyderabad, India 2 Dept of ECE, SNIST, Ghatkesar, Hyderabad, India 3 Abstract: A novel method for error correction for Very-high frequency Omni Range (VOR) Azimuth is designed and tested. The basic principle behind the working of VOR is enumerated. In the generation of phase difference at the air- borne receiver, various errors occur which impair the effective working of VOR. The aggregate value of these errors will be around ±5 o . Broadcom BCM2836R processor is used in the Linux environment with Mathematica10. Wolfram language is used to realize Kalman filter. Incorporating the proposed method, the aggregate error is successfully reduced to around ±1 o . This improvement will benefit the air operators to have more aircraft density surrounding any airport/VOR area. Keywords: Kalman filter, Very-high frequency Omni Range (VOR), Azimuth, Wolfram language. 1. INTRODUCTION This paper discusses various aspects regarding VOR function, its principles, wave pattern including functional description of VOR in general and various errors involved in the functioning of the VOR in particular are touched upon with a specific eye on improving the errors involved in the functioning of the VOR, especially after analysing the errors in ground check, course, station errors, side band errors, antenna errors, deruntal/ quadrantal errors and propogational effect errors. VOR is the most significant aviation invention in 1950s[1]. By using VOR, pilot can accurately navigate from point A to point B. There are two types of VOR, namely conventional VOR (CVOR) and Doppler VOR (DVOR). Even though both serve the same purpose as far as the aircraft are concerned, the selection of the CVOR and DVOR depends upon various site conditions in an airfield. The basic concepts of CVOR will be discussed. Here VOR theory, significance of VOR, generation of space wave pattern on the radiated signal is presented. The detailed error analysis of VOR is carried and the possible solutions to reduce the errors using Kalman Filter are offered. A. Omni-Range Omni-range is based on the radiation of two signals. One of the signal is transmitted Omni directionally modulated with carrier is known as reference signal. The second transmitted signal would have a field pattern with the shape of the figure of eight (8) but is not modulated. The Omni pattern is continuously rotated. If the pattern is rotated very slowly, an observer at a fixed point could record the values of the field strength on a meter. He would record exactly the same relative readings as if the pattern is fixed in the space and as he walks around the antenna with the indicating equipment. In one revolution of the figure-of-eight pattern the indicating meter would pass through two maxima and two null points in a sinusoidal manner. If this rotation is accomplished at a speed corresponding to the frequency of the reference signal modulation, the output of the indicator would be an audio note with the frequency equal to the reference signal modulation frequency. If the equipment is adjusted such that the voltage of the modulation frequency of the reference signal is a maximum as the figure of eight is passing through the north, then the audio frequency and the output frequency from the indicator will always be in phase, when observer is standing at north of the radio station. If now observer move towards east, his indicator will be at zero voltage when the modulating signal voltage is maximum therefore by reading the phase existing between the reference signal and variable signal the bearing of the observer‟s position with respect to the radio station can be determined directly [1]. A system of this type could be made to operate by transmitting the reference and variable phase signal on two different carrier frequencies that are received on separate receivers. To avoid the generation of two carriers, only one carrier