The light source is one of the key components of fiber optic gyroscopes (FOGs) since its optical parameters determine FOG performance, including the stability of the scale factor and zero bias. In this paper we consider the main types of light sources that are most suitable for FOGs. We describe the design principles and relevant technical characteristics of such sources, review commercially available sources, and provide a brief assessment of the prospects for the development of light sources in the context of fiber optic gyroscopy

Mass unbalance of a hemispherical resonator creates forces and moments affecting its center of mass and causing the oscillations of the resonator stem. A part of oscillation energy is dissipated in vicinity of the resonator joint, which reduces its Q factor and leads to additional systematic drift. The paper considers the main factors determining the dissipative characteristics of the resonator-foundation joint such as the resonator design and structure, internal friction in the bonding layer, and the defects in this layer. It has been shown that the internal friction due to attachment is proportional to the layer thickness and inversely proportional to the thickness of foundation, stem diameter, and elasticity modulus of the layer material. Asymmetric stem fixation in the opening in the foundation, ovality of this opening or the stem, bubbles in the bonding layer result in azimuth-depending losses and additional HRG systematic drift

In recent research, signicant eorts have focused on achieving dependable real-time positioning in challenging environments, which is a crucial aspect for the development of various Intelligent Transportation Systems (ITS) applications. Given the limitations of Global Navigation Satellite Systems (GNSS) in suburban and urban areas, where signal blockage is common, there is a growing need for an independent positioning system to provide accurate and continuous location data during GNSS disruptions. Previous studies have explored the combination of Light Detection and Ranging (LiDAR), gyroscopes, and odometer sensors for this purpose. This research builds upon that foundation by introducing a real-time calibration process for odometer readings, leveraging road maps and a road segmentation technique. To evaluate this method, real-world data collected from a moving vehicle was used, incorporating three ve-minute simulated GNSS outages. These data were processed in a simulated real-time mode. The results from these tests are promising, showing notable improvements in navigation accuracy. Specically, the application of the real-time calibration method led to an enhancement in positioning accuracy by 0.9m, 1.0m, and 0.2m for each of the GNSS outages, respectively, highlighting the critical role of this calibration process. The performance of the algorithm was improved during the second and third outages with the increased availability of line features. The proposed simpler LiDAR data processing algorithm could achieve mean positional errors of 1.8m and 1.8m, with maximum errors of 4.0m and 3.8m, respectively.

Astronomical calibration refers to determination of the constant mutual attitude of digital cameras and the inertial measurement unit using ground-based star observations. The first part of this paper considers calibrating the attitude of all cameras relative to the selected one. The calibrated vector contains the useful parameters (three attitude angles of each camera relative to the selected one) and interfering parameters (three attitude angles of the selected camera in the Earth-fixed frame at the time of shooting each frame). The system of nonlinear equations for determining the calibrated vector is based on the differences in the coordinates of images of the identified stars, which are calculated in the image planes of different cameras for each frame and then combined into a common residual vector. Atmospheric refraction and velocity aberration of light are considered when projecting the identified stars from the star catalog onto the image plane. Before solving the system of equations, intrinsic parameters of each camera are determined. Calibrating the relative attitude of real cameras provides a virtual camera with an extended field of view, which significantly reduces the error in star-based attitude determination. A virtual camera error model is provided that takes into account the errors in astronomical calibration. The results from experimental verification show that the error in astronomical calibration of the cameras’ relative attitude does not exceed 2 arcsec for each useful parameter.

A test platform is developed to provide experimental verification of attitude determination and control algorithms for a satellite. The testbed is used for the development and implementation of test cases including sensors, actuators, and algorithms. The sensor suite consists of magnetometers, accelerometers, and gyroscopes used for state estimation. Three reaction wheels are used on each axis as the primary attitude control actuator. the test setup consists of the main payload-carrying table, mass balancing blocks, adapters for equipment installation, in order to make the mass balance, coarse balancing blocks are placed on the four corners and fine ones are mounted on each principal axis. The platform has a wireless monitoring system and a power distribution unit for online analysis. A computer is used to manage attitude determination and control tasks in a distributed control mechanism. After testing the maneuverability of the control system, various scenarios are evaluated and analyzed for magnetometer calibration and for satellite attitude estimation using traditional and nontraditional kalman type filters.

The paper demonstrates an automatic algorithm for determining the coordinates and motion parameters of an underwater noise source detected by a submarine passive sonar. This algorithm does not require any special maneuvering of the observer vessel. The description of the algorithm and the results of its simulation for standard situations are presented.

The article presents the results of experimental testing of the possibility to perform data exchange with a deep-submerged underwater vehicle for solving the task of its inverse positioning using acoustic communication. The tests were performed in the equatorial zone of the Indian Ocean near the Sumatra Island in the water area with the average depth of 4700 m. The obtained data are compared with the results of simulation performed for the same conditions.

The article studies the operation results for a magnetic compass (MC) with a system for correcting dynamic errors. The efficiency of using a correction system to reduce MC errors occurring under the ship roll and pitch motion and conditioned by the influence of the ship’s redistributed magnetic forces (heeling deviation) and translational accelerations if the compass is installed at some distance from the ship’s oscillation center, is estimated.
The article analyzes the disturbing forces acting on the MC during roll and pitch motion and leading to its errors. The correction system based on a complementary filter using a MEMS gyroscope (MMG), implemented in the MC Azimuth KM-05D, is considered. The results from bench and field tests of the magnetic compass are presented, which confirm the effectiveness of this correction system.

The position of an artificial Earth satellite or the Moon is determined by laser ranging. Laser measurements of distances are carried out from ground stations to satellites equipped with corner reflectors or to the reflectors located on the surface of the Moon. The time interval between the emission and reception of ultrashort laser pulses at the same station make it possible to determine the position of the satellite or the Moon at the moment of reflection. In this case, the signal emitted from the station and the reflected signal from the satellite follow different paths. In this case, an angle is formed between the direction of the emitted and reflected signals at the location point. It is this deviation of laser signal paths that is the subject-matter of this paper. Since the Earth-fixed rotating reference frame is noninertial, calculations are performed with consideration for the theory of relativity. The spherical shape of the Earth and the Keplerian orbits of satellites are considered without taking into account the Earth’s gravitational field. The signal deviation significantly depends both on the satellite orbital parameters and the Earth’s rotation rate. The mathematical calculations allow the authors to generalize and compare the results of studies of this effect obtained from various available publications. They were also used in numerical calculations on the example of a high-orbit and high-eccentricity satellite RadioAstron and all of the 24 GLONASS low-orbit satellites with minor eccentricities. The magnitudes of both the effect itself and its variations depending on the changes in the satellite orbit parameters are calculated. The accuracy of modern instruments is sufficient to record the effect, and the result obtained will increase the efficiency of their application. In the future, it is planned to evaluate the factors of the Earth oblateness and its gravitational potential.