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AIS R-mode trilateration for GPS positioning and timing insurance

100%

Shyshkin O. V. , Konovets V. I. , Koshevyy V. M.

2024

tom Vol. 18 No. 2

369--374

Satellite navigation is the backbone of maritime navigation today. However, the technical vulnerability of on-board Global Navigation Satellite System (GNSS) receivers the satellite system greatly destabilizes maritime security due to the loss of ship’s position and accurate time. This article devoted to study an alternative method for obtaining coordinates and accurate time based on the use of automatic identification system (AIS) radio channels, so-called range mode (R-Mode). We use other AIS ship stations with reliable position data as reference stations and determine time of arrival for received AIS transmissions. To improve the accuracy of measuring signal arrival instance in the time difference of arrival (TDOA), that we utilize for trilateration, it is proposed signal oversampling and applying the fast Fourier transform (FFT) to the product of quadrature components of the baseband Gaussian minimum shift keying (GMSK) signal in the window of AIS time slot. To take into account the movement of other ships, appropriate coordinate corrections are foreseen, which can be calculated by dead reckoning or by the inertial navigation system of our ship. The proposed method is fully compatible with the existing AIS signals and may be employed in critical situations of locally limited (jamming, spoofing) GNSS abilities. It can be implemented as a separate unit, working for receiving in parallel with the mandatory AIS transponder.

A cooperative positioning algorithm for DSRC enabled vehicular networks

80%

Efatmaneshnik M. , Kealy A. , Alam N. , Dempster A.

tom Vol. 22

117--129

Many of the safety related applications that can be facilitated by Dedicated Short Range Communications (DSRC), such as vehicle proximity warnings, automated braking (e.g. at level crossings), speed advisories, pedestrian alerts etc., rely on a robust vehicle positioning capability such as that provided by a Global Navigation Satellite System (GNSS). Vehicles in remote areas, entering tunnels, high rise areas or any high multipath/ weak signal environment will challenge the integrity of GNSS position solutions, and ultimately the safety application it underpins. To address this challenge, this paper presents an innovative application of Cooperative Positioning techniques within vehicular networks. CP refers to any method of integrating measurements from different positioning systems and sensors in order to improve the overall quality (accuracy and reliability) of the final position solution. This paper investigates the potential of the DSRC infrastructure itself to provide an intervehicular ranging signal that can be used as a measurement within the CP algorithm. In this paper, time-based techniques of ranging are introduced and bandwidth requirements are investigated and presented. The robustness of the CP algorithm to inter-vehicle connection failure as well as GNSS dropouts is also demonstrated using simulation studies. Finally, the performance of the Constrained Kalman Filter used to integrate GNSS measurements with DSRC derived range estimates within a typical VANET is described and evaluated.