A Method for Determining the Bearing and Roll Angles of an Aircraft by an Orthogonally Linearly Polarized Beacon Signal
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TRONICS AND RADIO ENGINEERING
A Method for Determining the Bearing and Roll Angles of an Aircraft by an Orthogonally Linearly Polarized Beacon Signal V. L. Gulkoа and A. A. Mescheryakovа,* а
Tomsk State University of Control Systems and Radio Electronics, Tomsk, 634050 Russia *e-mail: [email protected]
Received May 18, 2020; revised May 28, 2020; accepted May 30, 2020
Abstract—Orthogonally linearly polarized radio-beacon signals are emitted simultaneously from two spatially separated points in the horizontal plane to determine the bearing and roll angles. The resulting vector signals from the radio beacon are received by a receiving antenna on board an aircraft. The antenna irradiator is equipped with a polarizing modulator in the form of a ferrite rotator of the polarization plane. The bearing and roll angles are estimated at the receiver output at a frequency that is a multiple of the polarization-modulation frequency of the received beacon signals. The layout of the apparatus that performs this method is described. The results of measuring the navigation elements are presented. The mean square errors of the bearing and roll angle measurements were 0.48° and 0.35°, respectively. DOI: 10.1134/S0020441220060068
INTRODUCTION One of the promising ways to expand the functionality of onboard and ground-based radio-navigation equipment is the practical use of the vector nature of radio signals as a carrier of navigation information. The existing methods for determining the angular position of an aircraft in radio-beacon navigation systems (RBSs) are based on the use of the amplitude, frequency, phase, or time characteristics of radio-beacon (RB) signals [1]. To measure the navigation elements such as the roll and pitch, expensive and technically complex inertial navigation tools are used [2]. However, the polarization characteristics of RB signals are virtually not used [3]. In [4–6], the possibility of using orthogonally linearly polarized RB signals was investigated for estimating the bearing [4, 5] and roll [6] of a mobile object using the polarization-modulation method. The essence of this method is that signals with vertical and horizontal polarizations and equal amplitudes, wavelengths λ, and known initial phases were emitted synchronously from two points spatially separated by a distance d in the horizontal plane. The resulting RB vector signals were received by a receiving antenna on board an aircraft; the singlechannel microwave path of this antenna includes a polarization modulator in the form of a mechanically rotating (at the frequency Ω) section of a circular waveguide with a half-wave λ/2 [4, 6] or quarter-wave λ/4 [5] phase plate, which is placed inside it. The phase plate is rotated by a stepper motor that is mechanically
connected to a circular-waveguide section. The bearing α was defined as the angle between the normal to the middle of the base d and the direction to the movable object using the formula [4–6]
α = ± arcsin
(2πλd Δϕ) ± nπ,
(1)
where n = 0, 1, 2…; Δϕ is the high-frequency phase di
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