Satellite-based Automatic Identification System Research Articles

The environmental niche of the squid-jigging fleet in the North Pacific Ocean based on automatic identification system data

The vast number of fishing fleets and limited regulatory capacity pose challenges to the effective monitoring and management of marine fishery resources. To understand the fishing characteristics of spatial distribution for squid-jigging fleets in the North Pacific Ocean (NPO), satellite-based automatic identification system (AIS) data during 2016 ∼ 2020 and marine environmental data were applied to explore the drivers of fishing activities based on the boosted regression tree (BRT) and generalized additive model (GAM). The results showed that the BRT model has better performance than the GAM. The spatial distribution of squid-jigging fleets has a significant seasonality. Specifically, the spatial distribution of Fishing effort (FE) gradually shifted to the northwest from May to September, while gradually shifted to the southwest from October to November. The favourable area for focusing FE was the 150°E ∼ 165°E, 40°N ∼ 44°N. The latitudinal distribution of FE was not wide and the longitudinal distribution was long. Variations in the marine environment constantly influenced the FE of the squid-jigging fleets. Overall, the influence of sea surface temperature (T0) on FE was most significant. The favourable range of T0 for FE was 12 ∼ 20°C. Water temperature at the 300 m depth (T300) was also an important factor through the fishing season. The favourable range of T300 for FE was 3 ∼ 6°C. There were obvious differences in the influence of other environmental factors on FE in different months. Different environmental variables drive the spatial distribution of fishing effort in different months. This study may help to scientifically and effectively guide fishery management and sustainable development by evaluating the spatial variations in fishing activity.

Comparison of Simulated and Measured Power of the Earth-Space Link for Satellite-Based AIS Signals.

This research aims to analyze the impact of the Earth-Space link on the Automatic Identification System (AIS) signals of ships. To achieve this, we established a simulation system that measures the receiving power of AIS signals via satellite platforms. We validated the system by utilizing observation data from Tiantuo-5. Through this simulation, we quantitatively analyzed the effects of ionospheric TEC (Total Electron Content) and space loss on the received power. During the processing of observation data, we construct a geometric propagation model utilizing the measured positions of both the satellite and the ship. We then calculate the antenna gain and remove any system errors. Additionally, we eliminate the deviation of elevation and azimuth angles caused by satellite motion. This allows us to determine the actual power of different ships reaching the receiving platform. Upon comparing the measured power data with the simulated power, it was noted that both exhibited an increasing trend as the elevation angle increased. This led to an RMSE (Root Mean Square Error) result of approximately one, indicating the accuracy of the simulation system. These findings hold significant implications for analyzing interference factors in satellite-ground links.

Vessel sailing route extraction and analysis from satellite-based AIS data using density clustering and probability algorithms

The vessel Automatic Identification System (AIS) data collected by satellites have the features of large coverage area and large data volume, and they are instantaneous discrete data rather than time-continuous data, so the data has large dispersion with many noise points. This poses a challenge for vessel sailing route extraction. This paper proposes a vessel sailing route extraction method which consists of the fast Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm and the Kernel Density Estimation-based Outlier Factor (KDE-based OF) noise reduction algorithm. The method in this paper firstly improves the clustering discrimination method in the DBSCAN algorithm to separate trajectories in different directions. Secondly, this paper extracts a fast clustering algorithm based on the density clustering algorithm to reduce its computing time overhead with satellite big data. Finally, this paper proposes the KDE-based OF processing algorithm, which calculates the outlier probability distribution value of the trajectory points through the algorithm to eliminate the edge trajectory points with low probability distribution. Based on the actual satellite vessel AIS data, this paper conducts multi-method comparisons and performance analysis experiments. Experiments show that the proposed method has the best stability and advancement.

An overview of the legal search and rescue framework and related infrastructure along the Arctic Northeast Passage

A quite extended number of commercial flights are transiting today through the Arctic Ocean. In addition, activities like tourism, fishing and local communities’ resupply needs, along with various planned and already existing maritime transport endeavors further point towards the direction of future higher demands on the Search and Rescue (SAR) infrastructure of the wider region. The "Agreement on Cooperation on Aeronautical and Maritime Search and Rescue in the Arctic" that coordinates international SAR coverage and response efforts in the region under discussion and establishes the area of (SAR) responsibility of each state party was the first legally-binding instrument negotiated and adopted under the auspices of the Arctic Council; this has been a very decisive step for the establishment and enhancement of SAR infrastructure in the Arctic. Through an exploratory review of various sources (resolutions and legislative documents of the International Maritime Organization, government policy documents of the Arctic Council Nations, academic literature) and primary data from institutions located in Norway and Russia, this paper aims to provide an overview of the existing SAR infrastructure of the countries in close proximity with the Northeast Passage, identify current deficiencies and propose ways forward for safe and sustainable voyages in the region. Valuable outcomes for policy-makers and relevant stakeholders come about from necessary investments in advanced SAR infrastructure to enhance safe and secure navigation in the Arctic, including the use of satellite-based Automatic Identification System (AIS) for monitoring vessel activities and improving awareness of their location and strengthened cooperation among the Arctic Council Nations to address the increased challenges of SAR operations in this remote geographical region.

Passive Maritime Surveillance Based on Low Earth Orbit Satellite Constellations

The rapid growth of maritime transportation and its regularization have imposed an increasing demand for developing a global maritime surveillance capacity. The existing cooperative maritime traffic monitoring relies on the shipborne automatic identification system (AIS), which is now confronting severe security threats due to the vulnerabilities of AIS at both the implementation and protocol levels. In this article, the possibility of passive AIS signal localization using low Earth orbit satellite constellations is investigated, which provides a more reliable vessel position determination. To this end, the article first presents an overview on two categories of passive localization methods. Realizations of these methods on the satellite-based AIS emitter position determination are then demonstrated and compared. To evaluate the system performance, the lower bound for the localization error is also derived. Focusing on the system realization, some general design considerations and localization accuracy optimization are further discussed.

Low profile Compact Printed Monopole Antenna for Satellite based AIS Application

In this paper, a simple, low profile compact printed monopole antenna has been proposed for satellite based automatic identification system (SB-AIS). The design consists of a printed monopole, which has been meandered to achieve optimum size reduction. The detailed investigation in terms of bending of the arms of monopole, width of the patch and dimensions of the ground plane on the resonance frequency and input impedance is presented. The antenna is matched to a typical 50 Ω coaxial line without any requirement of external matching structures. The prototype of the antenna is fabricated and tested at an operating frequency of 161 MHz for SB-AIS, with compact size of 44.5 . 17 cm2. The measured results show that the antenna has a bandwidth of 15 MHz (9.3 per cent), gain of 1.87 dBi and beam-width of 82° in the elevation and omnidirectional in azimuthal plane. The size reduction is 53.8 per cent as compared to a linear printed monopole antenna.

A Design of Space-borne AIS Scene Simulation Based on Density Distribution of Global Vessels

At present, the demand for application of space-borne Automatic Identification System (AIS) is increasing. Since more and more satellites are equipped with AIS payload, it is especially important to test the effectiveness of its performance. Owing to difficult test on AIS payload and high cost, this paper proposes a method of space-borne AIS scene simulation platform based on density distribution of global vessels, focusing on basic principle and design method of simulation scene. It contains detection range computing, the number of vessels within range and the detection probability of AIS receiver. Moreover, corresponding software and hardware have been designed. ‘Ocean-2B’ satellite-based AIS payload is used to test the performance of the scene simulation system, which indicates that the method can simulate real scene of receiving signals in orbit in a favourable manner.

Frequency offset estimation in the intermediate frequency for satellite-based AIS signals

In this paper, an accurate frequency offset estimator is investigated in the intermediate frequency for the satellite-based automatic identification system (AIS) signals. Using Gaussian minimum shift keying (GMSK) modulation for transmission, the AIS signal is shown to be a plane wave with the modulated phase information and carrier frequency resulting from the Doppler effects. Hence, the phase information can be eliminated with a re-modulated signal, and the frequency offset can be estimated by the ratio of the maximum spectral amplitude and its neighbor spectral amplitude based on the fast Fourier transformation (FFT) interpolation. The estimator has low complexity, and it is easy to implement. Computer simulations are used to assess the performance of the estimator.

Frequency Offset Estimation of Satellite-Based AIS Signals Based on Interpolated FFT

Aimed at addressing the problem of carrier synchronization for satellite-based Automatic Identification System (AIS) signals, a novel data-aided carrier frequency offset estimation method in the intermediate frequency is proposed in this paper. AIS signals use Gaussian Minimum Shift Keying (GMSK) for transmission, and a nonlinearity of the GMSK signal is shown to be a sine wave with frequency related to the carrier frequency offset. Based on that, this method constructs an auxiliary function with the available symbols to avoid the influence of the modulated phase information, and it estimates the frequency offset due to Doppler shift with a new interpolated FFT method. Moreover, this method performs better when the signals are filtered by band pass filter even through the bandwidth is as low as the 1/3 nominal bandwidth. Computer simulations are used to assess the synchronizer performance on AWGN channels.

Completing fishing monitoring with spaceborne Vessel Detection System (VDS) and Automatic Identification System (AIS) to assess illegal fishing in Indonesia

The Indonesian fisheries management system is now equipped with the state-of-the-art technologies to deter and combat Illegal, Unreported and Unregulated (IUU) fishing. Since October 2014, non-cooperative fishing vessels can be detected from spaceborne Vessel Detection System (VDS) based on high resolution radar imagery, which directly benefits to coordinated patrol vessels in operation context. This study attempts to monitor the amount of illegal fishing in the Arafura Sea based on this new source of information. It is analyzed together with Vessel Monitoring System (VMS) and satellite-based Automatic Identification System (Sat-AIS) data, taking into account their own particularities. From October 2014 to March 2015, i.e. just after the establishment of a new moratorium by the Indonesian authorities, the estimated share of fishing vessels not carrying VMS, thus being illegal, ranges from 42 to 47%. One year later in January 2016, this proportion decreases and ranges from 32 to 42%.

Statistical Analysis of the Detection Probability of the TianTuo-3 Space-based AIS

The Micro-Nano satellite TianTuo-3 (TT-3) developed by the National University of Defense Technology (NUDT) was successfully launched on 20 September 2015. The space-based Automatic Identification System (AIS) on board TT-3 works well and stably receives AIS signals from global vessels. In this work, we perform statistical analysis on the detection probability of the vessels in the concerned areas by using the TT-3 AIS data. The results suggest that the detection probability of vessels decreases as the distribution density increases, especially in the offshore areas of dense traffic and the TT3-AIS vessel detection probability in the oceans can be higher than 40%, indicating that the TT-3 AIS has achieved a high probability of coverage of vessels for a single receiving antenna. The analysis results will present helpful references both in evaluating the potential application of satellite-based AIS and for designing the next generation space-based AIS which might greatly improve the detection probability of ocean-going vessels.

The Ortelius Incident in the Hinlopen Strait—A Case Study on How Satellite-Based AIS Can Support Search and Rescue Operations in Remote Waters

In this paper, Automatic Identification System (AIS) data collected from space is used to demonstrate how the data can support search and rescue (SAR) operations in remote waters. The data was recorded by the Norwegian polar orbiting satellite AISSat-1. This is a case study discussing the Ortelius incident in Svalbard in early June 2016. The tourist vessel flying the flag of Cyprus experienced engine failure in a remote part of the Arctic Archipelago. The passengers and crew were not harmed. There were no Norwegian Coast Guard vessels in the vicinity. The Governor of Svalbard had to deploy her vessel Polarsyssel to assist the Ortelius. The paper shows that satellite-based AIS enables SAR coordination centers to swiftly determine the identity and precise location of vessels in the vicinity of the troubled ship. This knowledge makes it easier to coordinate SAR operations.

An Improved FastICA Algorithm Based on Modified-M Estimate Function

In order to improve the detection rate of ship information, fast independent component analysis (FastICA) algorithm is adopted to separate satellite-based automatic identification system (AIS) mixed signals. FastICA algorithm has the advantages of fast convergence rate and simple form. However, it is sensitive to the initialization of the separation matrix and the robust performance is poor. Aimed at the problem, an improved FastICA algorithm is proposed. This new algorithm is based on constant model of AIS signal and chooses Modified-M estimation function as nonlinear function so as to improve the robustness of algorithm. The improved algorithm also modifies Newton iterative algorithm. The experimental simulation results indicate that the proposed method reduces the iteration times and the accuracy has been improved.

GMSK iterative carrier recovery for AIS burst-mode

In this paper, an iterative carrier recovery algorithm of Gaussian filtered minimum shift keying (GMSK) in burst-mode was designed. The data utilization rate and precision of the traditional demodulation method for recovering carrier signal in burst data packet with limited-length is poor. In order to solve this problem, this paper proposed an iterative carrier recovery algorithm. This algorithm can improve the estimated precision of carrier recovery and data utilization rate of burst data packet in a large extent by performing multiple forward and backward iterations. And the algorithm can be implemented in Simulink environment. As the communication mode of automatic identification system (AIS) is abrupt, the algorithm is especially suitable for satellite-based AIS.

A Vessel Positioning Algorithm Based on Satellite Automatic Identification System

Vessels can obtain high precision positioning by using the global navigation satellite system (GNSS), but when the ship borne GNSS receiver fails, the existence of an alternative positioning system is important for the navigation safety of vessel. In this paper, a localization method based on the signals transmitted by satellite-based automatic identification system (AIS) is proposed for vessel in GNSS-denied environments. In the proposed method, the positioning model is a modification on the basis of time difference and frequency difference of arrival measurements by introducing an additional measurement, and the measurement is obtained through the interactive multiple model algorithm. The performance of the proposed strategy is evaluated through simulations, and the results validate the feasibility and reliability of vessel localization based on satellite-based AIS.

Non-coherent sequence detection scheme for satellite-based automatic identification system

The satellite-based automatic identification system (AIS) receiver has to encounter the frequency offset caused by the Doppler effect and the oscillator instability. This paper proposes a non-coherent sequence detection scheme for the satellite-based AIS signal transmitted over the white Gaussian noise channel. Based on the maximum likelihood estimation and a Viterbi decoder, the proposed scheme is capable of tolerating a frequency offset up to 5% of the symbol rate. The complexity of the proposed scheme is reduced by the state-complexity reduction, which is based on per-survivor processing. Simulation results prove that the proposed non-coherent sequence detection scheme has high robustness to frequency offset compared to the relative scheme when messages collision exists.

Frequency estimation of satellite-based automatic identification system signals

Frequency estimation of satellite-based automatic identification system signals

Can monitoring maritime activities in the European High Arctic by satellite-based Automatic Identification System enhance polar search and rescue?

This proof of concept paper seeks to determine whether monitoring maritime activities in the European High Arctic by satellite-based Automatic Identification System (AIS) can enhance polar search and rescue (SAR) by building an accurate temporal and spatial profile of the fleet of ships operating there. It quantifies maritime activities in three regions in the European High Arctic where it is probable that the Norwegian Coast Guard will be requested to assist in future SAR operations. The main focus is on the Svalbard region, which is located in the standard area of operation of the Norwegian Coast Guard. The analysis is based on data from the Norwegian satellites AISSat-1 and -2 from 10 July 2010 to 31 December 2014. The vessels are organized into groups, such as fishing vessels, passenger (tourist) vessels, icebreakers, research vessels, and tankers and cargo vessels, as identified by the unique Maritime Mobile Service Identity number within a ship’s automatically transmitted AIS messages. In this paper, the maritime activities of passenger vessels are discussed in detail. This paper presents results on the number and locations of such vessels in each of the three Arctic regions, and identifies activity trends. It is possible, for example, to determine season start and finish for tourist vessels and to extrapolate that the greater the number of times those vessels travel into the High Arctic, the greater the level of polar operational experience of the crews. Knowledge about the location of vessels in an area (situational awareness) is valuable in cases where SAR actions are required. The International Maritime Organization is finalizing implementation of the Polar Code for the safety of vessels, which will apply in both Polar Regions and will require additional information about the profile of the fleets of ships operating there. However, it must be noted that the AIS data is generally only continuously available from legitimate operators (e.g. licensed fishers, tourist operators and vessels on government service) and if the AIS is turned off, the vessel becomes virtually invisible. This methodology, therefore, is not a stand-alone system. Despite the current shortcomings, we recommend that other Polar nations consider using satellite-based AIS to establish situational awareness in remote waters.

Global Maritime Surveillance by Airliner-Based AIS Detection: Preliminary Analysis

Demands on security, safety, and environmental protection in worldwide shipping are steadily increasing. Shipboard broadcast transponders based on the Automatic Identification System (AIS) can be easily detected close to coastal or waterway areas. Satellite-based AIS receivers detect globally but are limited in high-density traffic areas. This paper investigates the challenges and performance of AIS detection on aircraft at altitudes between 8 500 m and 10 000 m. During flight trials over sea and land, AIS signals were recorded. Post-processing of the recorded data allows the evaluation but also faces challenges due to the nature of overlapping AIS signals at the aircraft. A comparison of detected signals at the aircraft with received AIS signals on the ground is given, including the evaluation of the reception footprint of the aircraft. Finally, a concept for worldwide AIS detection via airliners is presented. The study shows the potential for global complementary surveillance coverage via airliner-based AIS detection.

Satellite-based AIS and its Comparison with LRIT

The satellite‐based Automatic Identification System (AIS) system has continuously been developed by the shipping industry in recent years. This paper introduces the satellite‐based AIS including the concept, the system structure, the development and its new applications. The Long Range Identification and Tracking (LRIT) system, which is mandatory to be required on certain classes of ships engaged on international voyages to report their position at least every six hours using onboard communication means however, has similar kind of function of ship monitoring with the satellite‐based AIS system. Based on the basic introduction of the LRIT system, this paper presents the comprehensive comparison between satellite‐based AIS and LRIT in terms of the ship’s cost, the communication scheme, the monitoring coverage, the information details and the information creditability. The conclusion that the satellite‐based AIS should be encouraged to effectively play a complement role to the LRIT system is advanced in the paper.