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Radar characteristics of precipitation affecting the tracking of ship’s radar objects

Revenko V.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2022

Vol. 16 No. 3

491--494

In this paper, we consider the possibility of using the radar characteristics of precipitation in order to reduce the negative impact of the echo signal generated by them on the radar tracking of objects performed by the ship’s radar. In the formation of an echo signal by precipitation, both the precipitation particles themselves: their size, state (solid or liquid phase), shape, and the factors that determine their combined action (concentration, relative position, preferred orientation), are important. The size of rain particles when compared to the wavelength emitted by the ship's radar antenna contributes to the creation of a larger or smaller noise echo on the display of the ship's radar, the power of which in the Rayleigh scattering region toward the radar is characterized by the effective scattering area. Falling raindrops are a collection of randomly located reflectors and their scattering properties depend on the spatial distribution and regularity of movement. At the same time, the radar characteristics of clouds with precipitation generated by them can be used in ship radars to determine the intensity of the atmospheric process along the ship’s route, and the uncertainty in determining the attenuation of the power of an electromagnetic wave emitted by a ship’s radar antenna and passing through the precipitation zone can be reduced by simultaneous use of two wavelengths on which ship’s radars operate.

Architecture of positioning and tracking solutions for maritime applications

Ilcev S.D.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2022

Vol. 16 No. 3

481--489

This paper discusses the current and new satellite transponders for global tracking and detecting of oceangoing ships, assets, crew, passengers and any moving objects at sea for enhanced vessels traffic control and management. These transponders are able to monitor all maritime assets and to improve safety, security of movements and collision avoidance, especially during very bad weather conditions and visibility. By deployment of the Global Navigation Satellite System (GNSS) in integration with Inmarsat, Iridium and other satellite systems in one unit with antenna, it is possible to provide reliable positioning and tracking solutions for civilian maritime, other mobiles and personnel at different Radio Frequency (RF) bands. The existing and forthcoming space and ground segment for positioning and tracking solutions as a modern Satellite Asset Tracking (SAT) onboard ships, and other relating systems are discussed and benefits of these new technologies and solution for improved positioning and tracking are explored.

A study of optimization of Alpha-Beta-Gamma-Eta filter for tracking a high dynamic target

Jeong T., Pan B.F., Njonjo A.W.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2017

Vol. 11, no. 1

49--53

The tracking filter plays a key role in accurate estimation and prediction of maneuvering vessel’s position and velocity. Different methods are used for tracking. However, the most commonly used method is the Kalman filter and its modifications. The Alpha-Beta-Gamma filter is one of the special cases of the general solution pro-vided by the Kalman filter. It is a third order filter that computes the smoothed estimates of position, velocity and acceleration for the nth observation, and also predicts the next position and velocity. Although found to track a maneuvering target with a good accuracy than the constant velocity, Alpha-Beta filter, the Alpha-Beta-Gamma filter does not perform impressively under high maneuvers such as when the target is undergoing changing accelerations. This study, therefore, aims to track a highly maneuvering target experiencing jerky motions due to changing accelerations. The Alpha-Beta-Gamma filter is extended to include the fourth state that is, constant jerk to correct the sudden change of acceleration in order to improve the filter’s performance. Results obtained from simulations of the input model of the target dynamics under consideration indicate an improvement in performance of the jerky model, Alpha-Beta-Gamma-Eta, algorithm as compared to the constant acceleration model, Alpha-Beta-Gamma in terms of error reduction and stability of the filter during target maneuver.