Journal of Marine Science and Engineering

Research

17 pages, 10930 KiB

Open AccessCommunication

On Detection of Anomalous VHF Propagation over the Adriatic Sea Utilising a Software-Defined Automatic Identification System Receiver

by Sanjin Valčić and David Brčić

J. Mar. Sci. Eng. 2023, 11(6), 1170; https://doi.org/10.3390/jmse11061170 - 2 Jun 2023

Cited by 3 | Viewed by 1392

Abstract

This paper represents observations on detection of Very High Frequency (VHF) anomalous propagation over the area of the Adriatic Sea. During the research campaign, a Software Defined Radio (SDR) Automatic Identification System (AIS) receiver was employed for collection of AIS data packets at [...] Read more.

This paper represents observations on detection of Very High Frequency (VHF) anomalous propagation over the area of the Adriatic Sea. During the research campaign, a Software Defined Radio (SDR) Automatic Identification System (AIS) receiver was employed for collection of AIS data packets at a fixed location in the Northern Adriatic. Data were collected during the 24-h period (25 February 2023 15:32 LT to 26 February 2023 15:32 LT), providing information from 115 AIS targets, or 159 965 AIS packets with 54.3% Packet Error Rate (PER), respectively. Subsequent analysis and post-processing of successfully demodulated signals and decoded packets was presented further. In certain instances, the SDR AIS receiver detected, received and decoded data packets from AIS targets distant several orders of magnitude larger than the VHF nominal ranges. To determine the magnitude of line-of-sight and over-the-horizon radio waves propagation, the great circle distances between the SDR AIS receiver antenna and AIS packets’ decoded positions were calculated, revealing hundreds of Nautical Miles (NM). Possible reasons for these occurrences, including tropospheric scattering, diffraction, ionospheric sporadic E layer and refraction were discussed and evaluated, in accordance, among others, with the previous research. By exclusion criteria and neglection of possible causes, it was concluded that the enhanced, over-the-horizon propagation of AIS signals occurred as a result of refraction effects, namely trapping/ducting, subrefraction and superrefraction. Data from nine World Meteorological Organization (WMO) radiosondes surrounding the greater reception area were collected for the same observation periods. Atmospheric profiles were created using Advanced Refractive Effects Prediction System (AREPS) program, and analysed for each individual station measurement. The results confirmed anomalous, over-the-horizon enhanced propagation and their probable origins, i.e., the occurrence of refractive conditions in the atmosphere over the Adriatic Sea area. These findings provide a solid foundation for further research in the area of propagation of VHF signals and their anomalous features caused by the atmospheric phenomenon effects. Full article

(This article belongs to the Special Issue Advanced Marine Electronic Applications in Smart Ocean)

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14 pages, 2759 KiB

Open AccessArticle

A Carrier-Based Gardner Timing Synchronization Algorithm for BPSK Signal in Maritime Communication

by Fengzhong Qu, Zhengchao Li, Minhao Zhang, Xingbin Tu and Yan Wei

J. Mar. Sci. Eng. 2023, 11(4), 829; https://doi.org/10.3390/jmse11040829 - 13 Apr 2023

Viewed by 2956

Abstract

Wireless communication at sea is an essential way to establish a smart ocean. In the communication system, however, signals are affected by the carrier frequency offset (CFO), which results from the Doppler effect and crystal frequency offset. The offset deteriorates the demodulation performance [...] Read more.

Wireless communication at sea is an essential way to establish a smart ocean. In the communication system, however, signals are affected by the carrier frequency offset (CFO), which results from the Doppler effect and crystal frequency offset. The offset deteriorates the demodulation performance of the communication system. The conventional Gardner bit-synchronization algorithm performs timing synchronization on the baseband, but it fails to solve the problem of carrier frequency offset. In this paper, a carrier-based timing-synchronization Gardner algorithm was proposed. The algorithm performed error detection in the carrier signal to estimate the synchronization error in real time and the time-domain expansion in the passband signal. Based on the estimated expansion factor, the algorithm located the sampling points of the ideal signal and re-interpolated all the sampling points on the passband to recover the passband signal without Doppler. This algorithm can solve both the frequency shift and time-domain expansion caused by the Doppler effect without further CFO estimation and compensation, thus reducing the overall computational complexity of the system. The simulations showed that the proposed algorithm greatly improves the ability of the communication system to combat Doppler compared to the conventional Gardner algorithm. The algorithm is primarily designed for binary phase-shift keying (BPSK)-modulated signals under the additive white Gaussian noise (AWGN) channel and can be applied to various maritime communication scenarios. Full article

(This article belongs to the Special Issue Advanced Marine Electronic Applications in Smart Ocean)

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15 pages, 1676 KiB

Open AccessArticle

A Multi-Beam Seafloor Constant False Alarm Detection Method Based on Weighted Element Averaging

by Jian Wang, Haisen Li, Guanying Huo, Chao Li and Yuhang Wei

J. Mar. Sci. Eng. 2023, 11(3), 513; https://doi.org/10.3390/jmse11030513 - 27 Feb 2023

Cited by 4 | Viewed by 1224

Abstract

Due to the influence of environmental noise, sidelobe data, and tunnel emission under the background of multi-background underwater surveying and mapping, it is challenging to detect seafloor terrain in the background noise. Constant false alarm detection of seafloor terrain under the condition of [...] Read more.

Due to the influence of environmental noise, sidelobe data, and tunnel emission under the background of multi-background underwater surveying and mapping, it is challenging to detect seafloor terrain in the background noise. Constant false alarm detection of seafloor terrain under the condition of constant false alarm probability has been an important research field. The constant false alarm detection can eliminate noise interference in a water body in the seabed topography mapping process and provide clear and accurate seabed topography information. Therefore, it is a challenging task to increase the detection probability, reduce the missing probability, and increase the detection speed in constant false alarm detection methods. Aiming at the shortcomings of the existing algorithms, this paper proposes an efficient weighted cell averaged constant false alarm detection method (WCA-CFAR). First, the cross-window reference unit sampling method is used to improve the detection speed and accurately sample the background noise unit. Then, the reference unit weighted average constant false alarm detection method is employed to calculate the detection threshold to achieve the purpose of target detection. The proposed method is verified by the simulation data detection test and a test on the actual lake test data. The test results show that the proposed method can effectively reduce the missing detection probability and improve the detection probability. Full article

(This article belongs to the Special Issue Advanced Marine Electronic Applications in Smart Ocean)

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14 pages, 4073 KiB

Open AccessArticle

Improving Ship Detection Based on Decision Tree Classification for High Frequency Surface Wave Radar

by Zhiqing Yang, Yeping Lai, Hao Zhou, Yingwei Tian, Yao Qin and Zongwang Lv

J. Mar. Sci. Eng. 2023, 11(3), 493; https://doi.org/10.3390/jmse11030493 - 24 Feb 2023

Cited by 4 | Viewed by 1314

Abstract

The traditional constant false alarm rate (CFAR) method, with fixed parameter settings and single noise background calculation, is unable to intelligently catch the current detection background. To improve the performance of the CFAR method, this paper proposes a target detection method based on [...] Read more.

The traditional constant false alarm rate (CFAR) method, with fixed parameter settings and single noise background calculation, is unable to intelligently catch the current detection background. To improve the performance of the CFAR method, this paper proposes a target detection method based on decision tree classification (DTC) for high-frequency surface wave radar (HFSWR). Firstly, the training sample set and labels are obtained by means of a ship automatic identification system (AIS). Then, feature vector of range dimension, Doppler dimension and range-Doppler (RD) dimension is extracted by way of cell averaging, ordered statistics, censored mean and trimmed mean. Finally, DTC is used to recognize “true” and “false” targets in feature space. Experimental results show that, under the same number of detection targets, the DTC method is superior to traditional CFAR methods, and the accuracy of target detection can be increased by more than 5%. Full article

(This article belongs to the Special Issue Advanced Marine Electronic Applications in Smart Ocean)

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24 pages, 9213 KiB

Open AccessArticle

Design of Control System for Multistage Distillation Seawater Desalination Device Driven by Photovoltaic-Thermal

by Jiaqi Yan, Chengjun Qiu, Yuangan Wang, Ning Wu, Wei Qu, Yuan Zhuang, Guohui Yan, Ping Wang, Ruoyu Zhang, Yirou Yan, Ruonan Deng, Jiuqiang Luo, Jiaqi Gao and Yuxuan Wu

J. Mar. Sci. Eng. 2023, 11(1), 222; https://doi.org/10.3390/jmse11010222 - 14 Jan 2023

Cited by 2 | Viewed by 2156

Abstract

This research proposes a seawater desalination system driven by photovoltaic and solar thermal energy for remote regions such as islands and seaside villages where fresh water is not accessible. The performance of this system is demonstrated through experiments, and the main concerns are [...] Read more.

This research proposes a seawater desalination system driven by photovoltaic and solar thermal energy for remote regions such as islands and seaside villages where fresh water is not accessible. The performance of this system is demonstrated through experiments, and the main concerns are the output of the photovoltaic power generation system, power quantity, water yield, and the loads under different solar irradiance and temperature. In this system, a PLC is used as the controller to adjust the water pump by the collection and processing of sensor data. A load switching time system is designed to select different operating schemes under different environments in order to save energy. The control method of this system is developed to ensure that the photovoltaic power generation system does not undervoltage while maintaining the normal operation of the desalination system. An improved Perturbation and Observation (P&O) algorithm is also proposed as a new Maximum Point Power Tracking (MPPT) method to solve the problem of misjudgment and oscillation after tracking the maximum power point (MPP) in the traditional P&O algorithm. The simulation test in the MATLAB/Simulink environment shows that when external irradiance changes, the improved P&O algorithm can track the MPP faster than the traditional P&O algorithm, and the amplitude of oscillation on the MPP is smaller. The hardware experiments show that this system can operate stably and flexibly, and it is capable of producing 5.18 kWh of electric energy and 335.81 kg of freshwater per day. The maximum yield of the unit can reach 565.75 kg per day and the maximum daily power generation is 8.12 kWh. Full article

(This article belongs to the Special Issue Advanced Marine Electronic Applications in Smart Ocean)

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11 pages, 2150 KiB

Open AccessCommunication

A Novel Conformal Coil Structure Design of Wireless Power Transfer System for Autonomous Underwater Vehicles

by Peizhou Liu, Tiande Gao, Ruixuan Zhao and Zhaoyong Mao

J. Mar. Sci. Eng. 2022, 10(7), 875; https://doi.org/10.3390/jmse10070875 - 25 Jun 2022

Cited by 6 | Viewed by 1705

Abstract

A coil structure that is compatible with the structure of the autonomous underwater vehicles (AUVs) and preventing the rotational misalignment is proposed for stabilizing the output power of a wireless power transfer (WPT) system. The transmitting coil and the receiving coil are wound [...] Read more.

A coil structure that is compatible with the structure of the autonomous underwater vehicles (AUVs) and preventing the rotational misalignment is proposed for stabilizing the output power of a wireless power transfer (WPT) system. The transmitting coil and the receiving coil are wound on the structure of the energy base station and the AUV in a spiral tube type, respectively. This arrangement not only guarantees a constant mutual inductance when the AUV rotates, but it also maintains the efficient transmission of energy when the receiving coil is conformal with the AUV by optimizing the size of the magnetic core and the distance between the coil and the metal structure. The performance of the proposed coil structure is experimentally evaluated by building an inductor–capacitor–capacitor series (LCC-S)-compensated WPT prototype. It was found that the system can stably deliver a 2 kW power with a dc–dc efficiency of 92.7%. Full article

(This article belongs to the Special Issue Advanced Marine Electronic Applications in Smart Ocean)

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14 pages, 2856 KiB

Open AccessFeature PaperArticle

A Block Sparse-Based Dynamic Compressed Sensing Channel Estimator for Underwater Acoustic Communication

by Lingji Xu, Lixing Chen, Yaan Li and Weihua Jiang

J. Mar. Sci. Eng. 2022, 10(4), 536; https://doi.org/10.3390/jmse10040536 - 14 Apr 2022

Cited by 4 | Viewed by 2142

Abstract

Due to the complex ocean propagation environments, the underwater acoustic (UWA) multipath channel often exhibits block sparse time-varying features, and while dynamic compressed sensing (DCS) can mitigate the time-varying effects of the UWA channel, DCS-based algorithms have limited performance for the UWA channel [...] Read more.

Due to the complex ocean propagation environments, the underwater acoustic (UWA) multipath channel often exhibits block sparse time-varying features, and while dynamic compressed sensing (DCS) can mitigate the time-varying effects of the UWA channel, DCS-based algorithms have limited performance for the UWA channel with block sparsity. In this study, by formulating the UWA channel with blocks concatenation, a block sparse-based DCS approach (BS-CS) is proposed to explore the block and time-varying sparsity of UWA channel simultaneously. In detail, we firstly adopt a block sparse recovery algorithm, block orthogonal matching pursuit (BOMP), to compute the temporary estimate. Then, the CS approach is applied to compute the support additions, which are caused by the time-varying components of the UWA channel. Next, we use the selected support to perform the BOMP estimate, and obtain the estimated channel response. Finally, the numerical simulation and the sea experiment were carried out to verify the superior performance of the proposed BS-CS algorithm in the block sparse time-varying UWA channels. Full article

(This article belongs to the Special Issue Advanced Marine Electronic Applications in Smart Ocean)

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10 pages, 4123 KiB

Open AccessArticle

Rolling Spherical Triboelectric Nanogenerators (RS-TENG) under Low-Frequency Ocean Wave Action

by Yuzhou Wang, Ali Matin Nazar, Jiajun Wang, Kequan Xia, Delin Wang, Xiaosheng Ji and Pengcheng Jiao

J. Mar. Sci. Eng. 2022, 10(1), 5; https://doi.org/10.3390/jmse10010005 - 22 Dec 2021

Cited by 29 | Viewed by 4537

Abstract

Triboelectric nanogenerators (TENG), which convert mechanical energy (such as ocean waves) from the surrounding environment into electrical energy, have been identified as a green energy alternative for addressing the environmental issues resulting from the use of traditional energy resources. In this experimental design, [...] Read more.

Triboelectric nanogenerators (TENG), which convert mechanical energy (such as ocean waves) from the surrounding environment into electrical energy, have been identified as a green energy alternative for addressing the environmental issues resulting from the use of traditional energy resources. In this experimental design, we propose rolling spherical triboelectric nanogenerators (RS-TENG) for collecting energy from low-frequency ocean wave action. Copper and aluminum were used to create a spherical frame which functions as the electrode. In addition, different sizes of spherical dielectric (SD1, SD2, SD3, and SD4) were developed in order to compare the dielectric effect on output performance. This design places several electrodes on each side of the spherical structure such that the dielectric layers are able to move with the slightest oscillation and generate electrical energy. The performance of the RS-TENG was experimentally investigated, with the results indicating that the spherical dielectrics significantly impact energy harvesting performance. On the other hand, the triboelectric materials (i.e., copper and aluminum) play a less important role. The copper RS-TENG with the largest spherical dielectrics is the most efficient structure, with a maximum output of 12.75 V in open-circuit and a peak power of approximately 455 nW. Full article

(This article belongs to the Special Issue Advanced Marine Electronic Applications in Smart Ocean)

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23 pages, 15755 KiB

Open AccessArticle

Viability and Performance Analysis, at a Physical Level, of a Maritime Communication Network on Medium Frequency

by Alfonso-Isidro López-Diaz, Miguel A. Gutiérrez, Andrés Ortega Piris, Emma Díaz-Ruiz-Navamuel and David Rodríguez-Rosa

J. Mar. Sci. Eng. 2021, 9(9), 970; https://doi.org/10.3390/jmse9090970 - 6 Sep 2021

Cited by 1 | Viewed by 1656

Abstract

This paper analysed the potentialities that have not yet been exploited of the Automatic Vessel Identification System on Medium Frequency (AVISOMEF) that was previously presented to the scientific community. This system expanded the spectrum of possibilities of the Global Maritime Distress and Safety [...] Read more.

This paper analysed the potentialities that have not yet been exploited of the Automatic Vessel Identification System on Medium Frequency (AVISOMEF) that was previously presented to the scientific community. This system expanded the spectrum of possibilities of the Global Maritime Distress and Safety System (GMDSS). By the time AVISOMEF was presented, one of the unexpected benefits was that it could constitute a platform capable of supporting a Maritime Communication Network on Medium Frequency; all remotely located vessels could communicate with each other by using AVISOMEF, making use of the new established network, within the geographic area of implementation, without needing to use satellite techniques. Medium frequency propagation is stable and is not subject to coverage restrictions. To conduct this experiment, we collaborated with the Spanish Maritime Safety Agency (SASEMAR). It was thanks to them that we gathered real-time information about the nationwide maritime traffic that navigated through the Spanish Search and Rescue jurisdiction waters from 2018 to 2020. Full article

(This article belongs to the Special Issue Advanced Marine Electronic Applications in Smart Ocean)

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