scholarly journals Detection, Localization and Classification of Multiple Mechanized Ocean Vessels over Continental-Shelf Scale Regions with Passive Ocean Acoustic Waveguide Remote Sensing

2018 ◽  
Vol 10 (11) ◽  
pp. 1699 ◽  
Author(s):  
Chenyang Zhu ◽  
Heriberto Garcia ◽  
Anna Kaplan ◽  
Matthew Schinault ◽  
Nils Handegard ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Continental Shelf ◽  
Signal To Noise Ratio ◽  
Automatic Identification ◽  
Identification System ◽  
Underwater Sound ◽  
Constant Frequency ◽  
Acoustic Waveguide ◽  
Time Frequency ◽  
Hydrophone Array

Multiple mechanized ocean vessels, including both surface ships and submerged vehicles, can be simultaneously monitored over instantaneous continental-shelf scale regions >10,000 km 2 via passive ocean acoustic waveguide remote sensing. A large-aperture densely-sampled coherent hydrophone array system is employed in the Norwegian Sea in Spring 2014 to provide directional sensing in 360 degree horizontal azimuth and to significantly enhance the signal-to-noise ratio (SNR) of ship-radiated underwater sound, which improves ship detection ranges by roughly two orders of magnitude over that of a single hydrophone. Here, 30 mechanized ocean vessels spanning ranges from nearby to over 150 km from the coherent hydrophone array, are detected, localized and classified. The vessels are comprised of 20 identified commercial ships and 10 unidentified vehicles present in 8 h/day of Passive Ocean Acoustic Waveguide Remote Sensing (POAWRS) observation for two days. The underwater sounds from each of these ocean vessels received by the coherent hydrophone array are dominated by narrowband signals that are either constant frequency tonals or have frequencies that waver or oscillate slightly in time. The estimated bearing-time trajectory of a sequence of detections obtained from coherent beamforming are employed to determine the horizontal location of each vessel using the Moving Array Triangulation (MAT) technique. For commercial ships present in the region, the estimated horizontal positions obtained from passive acoustic sensing are verified by Global Positioning System (GPS) measurements of the ship locations found in a historical Automatic Identification System (AIS) database. We provide time-frequency characterizations of the underwater sounds radiated from the commercial ships and the unidentified vessels. The time-frequency features along with the bearing-time trajectory of the detected signals are applied to simultaneously track and distinguish these vessels.

scholarly journals LPI Radar Waveform Recognition Based on CNN and TPOT

Symmetry ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 725 ◽  
Author(s):  
Jian Wan ◽  
Xin Yu ◽  
Qiang Guo
Keyword(s):  
Signal To Noise Ratio ◽  
Recognition Rate ◽  
Recognition System ◽  
Radar Signal ◽  
Automatic Identification ◽  
Identification System ◽  
Electronic Warfare ◽  
Time Frequency ◽  
Barker Codes ◽  
Intelligence Support

The electronic reconnaissance system is the operational guarantee and premise of electronic warfare. It is an important tool for intercepting radar signals and providing intelligence support for sensing the battlefield situation. In this paper, a radar waveform automatic identification system for detecting, tracking and locating low probability interception (LPI) radar is studied. The recognition system can recognize 12 different radar waveform: binary phase shift keying (Barker codes modulation), linear frequency modulation (LFM), Costas codes, polytime codes (T1, T2, T3, and T4), and polyphase codes (comprising Frank, P1, P2, P3 and P4). First, the system performs time–frequency transform on the LPI radar signal to obtain a two-dimensional time–frequency image. Then, the time–frequency image is preprocessed (binarization and size conversion). The preprocessed time–frequency image is then sent to the convolutional neural network (CNN) for training. After the training is completed, the features of the fully connected layer are extracted. Finally, the feature is sent to the tree structure-based machine learning process optimization (TPOT) classifier to realize offline training and online recognition. The experimental results show that the overall recognition rate of the system reaches 94.42% when the signal-to-noise ratio (SNR) is −4 dB.

scholarly journals Ship noise in an urban estuary extends to frequencies used for echolocation by endangered killer whales

2015 ◽  
Author(s):  
Scott Veirs ◽  
Val Veirs ◽  
Jason D Wood
Keyword(s):  
Transmission Loss ◽  
Source Spectrum ◽  
Automatic Identification ◽  
Identification System ◽  
Underwater Sound ◽  
Killer Whales ◽  
Noise Sources ◽  
Low Frequencies ◽  
High Frequencies ◽  
Location Data

Combining calibrated hydrophone measurements with vessel location data from the Automatic Identification System, we estimate underwater sound pressure levels for 1,582 unique ships that transited the core critical habitat of the endangered Southern Resident killer whales during 28 months between March, 2011, and October, 2013. Median received spectrum levels of noise from 2,812 isolated transits are elevated relative to median background levels not only at low frequencies (20-30 dB re 1 μPa2/Hz from 100-1000 Hz), but also at high frequencies (5-13 dB re 1 μPa2/Hz from 10,000-96,000 Hz). Thus, noise received from ships at ranges less than 3 km extends to frequencies used by odontocetes like the southern resident killer whales for communication and echolocation. Broadband received levels (11.5-40,000 Hz) near the shoreline in Haro Strait (WA, USA) for the entire ship population were 111 ± 6 dB re 1 μPa on average. Mean ship speed was 14.4 ± 4.1 knots. Most ship classes show a linear relationship between received level and speed with a slope near +1 dB/knot. Assuming near-spherical spreading based on a transmission loss experiment we compute mean broadband source levels for the ship population of 173 ± 7 dB re 1 μPa @ 1 m without accounting for frequency-dependent absorption. Spectrum, 1/12- octave, and 1/3-octave source levels for the whole population have median values that are comparable to previous measurements and models at most frequencies, but for select studies may be relatively low below 200 Hz and high above 20,000 Hz. Median source spectrum levels peak near 50 Hz for all 12 ship classes, have a maximum of 159 dB re 1 μPa2/Hz @ 1 m for container ships, and vary between classes by about 25 dB re 1 μPa2/Hz @ 1 m at low frequencies (50 Hz), 13 dB re 1 μPa2/Hz @ 1 m at mid-frequencies (1,000 Hz), and 5 dB re 1 μPa2/Hz @ 1 m at high frequencies (10,000 Hz). Below 200 Hz, the class-specific median spectrum levels bifurcate with large commercial ships grouping as higher power noise sources. Within all ship classes spectrum levels vary more at low frequencies than at high frequencies, and the degree of variability is almost halved for classes that have smaller speed standard deviations.

scholarly journals Ship noise extends to frequencies used for echolocation by endangered killer whales

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1657 ◽  
Author(s):  
Scott Veirs ◽  
Val Veirs ◽  
Jason D. Wood
Keyword(s):  
Transmission Loss ◽  
Source Spectrum ◽  
Automatic Identification ◽  
Identification System ◽  
Underwater Sound ◽  
Killer Whales ◽  
Noise Sources ◽  
Low Frequencies ◽  
High Frequencies ◽  
Location Data

Combining calibrated hydrophone measurements with vessel location data from the Automatic Identification System, we estimate underwater sound pressure levels for 1,582 unique ships that transited the core critical habitat of the endangered Southern Resident killer whales during 28 months between March, 2011, and October, 2013. Median received spectrum levels of noise from 2,809 isolated transits are elevated relative to median background levels not only at low frequencies (20–30 dB re 1 µPa2/Hz from 100 to 1,000 Hz), but also at high frequencies (5–13 dB from 10,000 to 96,000 Hz). Thus, noise received from ships at ranges less than 3 km extends to frequencies used by odontocetes. Broadband received levels (11.5–40,000 Hz) near the shoreline in Haro Strait (WA, USA) for the entire ship population were 110 ± 7 dB re 1 µPa on average. Assuming near-spherical spreading based on a transmission loss experiment we compute mean broadband source levels for the ship population of 173 ± 7 dB re 1 µPa 1 m without accounting for frequency-dependent absorption. Mean ship speed was 7.3 ± 2.0 m/s (14.1 ± 3.9 knots). Most ship classes show a linear relationship between source level and speed with a slope near +2 dB per m/s (+1 dB/knot). Spectrum, 1/12-octave, and 1/3-octave source levels for the whole population have median values that are comparable to previous measurements and models at most frequencies, but for select studies may be relatively low below 200 Hz and high above 20,000 Hz. Median source spectrum levels peak near 50 Hz for all 12 ship classes, have a maximum of 159 dB re 1 µPa2/Hz @ 1 m for container ships, and vary between classes. Below 200 Hz, the class-specific median spectrum levels bifurcate with large commercial ships grouping as higher power noise sources. Within all ship classes spectrum levels vary more at low frequencies than at high frequencies, and the degree of variability is almost halved for classes that have smaller speed standard deviations. This is the first study to present source spectra for populations of different ship classes operating in coastal habitats, including at higher frequencies used by killer whales for both communication and echolocation.

Detection, localization, and classification of multiple ocean vehicles over continental-shelf regions with passive ocean acoustic waveguide remote sensing

2017 ◽  
Vol 142 (4) ◽  
pp. 2495-2495
Author(s):  
Chenyang Zhu ◽  
Nada Saghir ◽  
Haoqing Li ◽  
WEI HUANG ◽  
Olav Rune Godø ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Continental Shelf ◽  
Acoustic Waveguide

scholarly journals Applying an Adaptive Signal Identification Method to Improve Vessel Echo Detection and Tracking for SeaSonde HF Radar

2021 ◽  
Vol 13 (13) ◽  
pp. 2453
Author(s):  
Laurence Chuang ◽  
Yu-Ru Chen ◽  
Yu-Jen Chung
Keyword(s):  
Remote Sensing ◽  
Hf Radar ◽  
Automatic Identification ◽  
Identification System ◽  
Signal Identification ◽  
Identification Method ◽  
Maritime Surveillance ◽  
Detection And Tracking ◽  
Echo Detection ◽  
Adaptive Signal

To enhance remote sensing for maritime safety and security, various sensors need to be integrated into a centralized maritime surveillance system (MSS). High-frequency (HF) radar systems are a type of mainstream technology widely used in international marine remote sensing and have great potential to detect distant sea surface targets due to their over-the-horizon (OTH) capability. However, effectively recognizing targets in spectra with intrinsic strong disturbance echoes and random environmental noise is still challenging. To avoid the above problem, this paper proposes an adaptive signal identification method to detect target signals based on a rapid and flexible threshold. By integrating a watershed segmentation algorithm, the subsequent direction result can be used to automatically compute the direction of arrival (DOA) of the targets. To assist in the orientation of the object, forward intersections are integrated with the technique. Hence, the proposed technique can effectively recognize vessel echoes with automatic identification system (AIS) verification. Experiments have demonstrated the promising feasibility of the proposed method’s performance.

Long Range Passive Ocean Acoustic Waveguide Remote Sensing (POAWRS) of Seismo-acoustic Airgun Signals Received on a Coherent Hydrophone Array

2019 ◽  
Author(s):  
Sai Geetha Seri ◽  
Chenyang Zhu ◽  
Matthew Schinault ◽  
Heriberto Garcia ◽  
Nils Olav Handegard ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Long Range ◽  
Acoustic Waveguide ◽  
Hydrophone Array

scholarly journals Slower Ship Speed in the Bahamas Due to COVID-19 Produces a Dramatic Reduction in Ocean Sound Levels

2021 ◽  
Vol 8 ◽  
Author(s):  
Charlotte Dunn ◽  
James Theriault ◽  
Leigh Hickmott ◽  
Diane Claridge
Keyword(s):  
Sperm Whale ◽  
Mitigation Measures ◽  
Automatic Identification ◽  
Identification System ◽  
Density Level ◽  
Underwater Sound ◽  
Sperm Whales ◽  
Ship Traffic ◽  
Sound Levels ◽  
Ship Speed

As underwater noise from ship traffic increases, profound effects on the marine environment highlight the need for improved mitigation measures. One measure, reduction in ship speed, has been shown to be one of the key drivers in reducing sound source levels of vessels. In 2017, a study began to assess the impacts of increasing commercial shipping traffic on sperm whales in Northwest Providence Channel, northern Bahamas, an international trade route that primarily serves the southeast US. Ship data were collected from an Automatic Identification System (AIS) station combined with recordings from an acoustic recorder to measure underwater sound levels and to detect the presence of sperm whales. Here we analyze a subset of these data to opportunistically investigate potential changes in ship traffic before and during the COVID-19 pandemic. These data span one calendar year from October 2019 to October 2020. A pre-COVID-19 dataset of 121 days, from a recorder approximately 2 km from the shipping route was compared to a 134-day dataset collected during COVID-19 from the same site, comprising 2900 and 3181 ten-minute recordings, respectively. A dramatic decrease in ocean noise levels concurrent with changes in shipping activity occurred during the pandemic. The mean pre-COVID-19 power density level in the 111–140 Hz 1/3-octave band was 88.81 dB re 1 μPa (range 81.38–100.90) and decreased to 84.27 dB re 1 μPa (range 78.60–99.51) during COVID-19, equating to a 41% reduction in sound pressure levels (SPL). After differences in seasonal changes in wind speed were accounted for, SPL decreased during the pandemic by 3.98 dB (37%). The most notable changes in ship activity were significantly reduced vessel speeds for all ship types and fewer ships using the area during the pandemic. Vessel speed was highly correlated to SPL and the only ship-based variable that predicted SPLs. Despite the opportunistic nature [i.e., not a standard before-after-control-impact (BACI) study], this study provides a unique opportunity to assess the effectiveness of ship traffic management strategies, such as slowing ships down, to mitigate impacts on marine life in the study area, including local sperm whale populations.

scholarly journals Ship noise in an urban estuary extends to frequencies used for echolocation by endangered killer whales

2015 ◽  
Author(s):  
Scott Veirs ◽  
Val Veirs ◽  
Jason D Wood
Keyword(s):  
Transmission Loss ◽  
Source Spectrum ◽  
Automatic Identification ◽  
Identification System ◽  
Underwater Sound ◽  
Killer Whales ◽  
Noise Sources ◽  
Low Frequencies ◽  
High Frequencies ◽  
Location Data

Combining calibrated hydrophone measurements with vessel location data from the Automatic Identification System, we estimate underwater sound pressure levels for 1,582 unique ships that transited the core critical habitat of the endangered Southern Resident killer whales during 28 months between March, 2011, and October, 2013. Median received spectrum levels of noise from 2,812 isolated transits are elevated relative to median background levels not only at low frequencies (20-30 dB re 1 microPa2/Hz from 100-1000 Hz), but also at high frequencies (5-13 dB re 1 microPa2/Hz from 10,000-96,000 Hz). Thus, noise received from ships at ranges less than 3 km extends to frequencies used by odontocetes like the Southern Resident orcas for communication and echolocation. Broadband received levels (20-96,000 Hz) near the shoreline in Haro Strait (WA, USA) for the entire ship population were 111 +/- 6 dB re 1 microPa on average. Mean ship speed was 14.4 +/- 4.1 knots. Most ship classes show a linear relationship between received level and speed with a slope near +1 dB/knot. Assuming near-spherical spreading based on a transmission loss experiment, we compute mean broadband source levels for the ship population of 173 +/- 7 dB re 1 microPa @ 1 m without accounting for frequency-dependent absorption, and 178 +/- 13 dB re 1 microPa @ 1 m with absorption. Spectrum, 1/12-octave, and 1/3-octave source levels for the whole population have median values that are comparable to previous measurements and models at most frequencies, but for select studies may be relatively low below 200 Hz and high above 20,000 Hz. Median source spectrum levels (without accounting for absorption) peak near 50 Hz for all 12 ship classes, have a maximum of 159 dB re 1 microPa2/Hz @ 1 m for container ships, and vary between classes by about 25 dB re 1 microPa2/Hz @ 1 m at low frequencies (50 Hz), 13 dB re 1 microPa2/Hz @ 1 m at mid-frequencies (1,000 Hz), and 5 dB re 1 microPa2/Hz @ 1 m at high frequencies (10,000 Hz). Below 200 Hz, the class-specific median spectrum levels bifurcate with large commercial ships grouping as higher power noise sources. Within all ship classes spectrum levels vary more at low frequencies than at high frequencies, and the degree of variability is almost halved for classes that have smaller speed standard deviations.

scholarly journals Space Remote Sensing and Detecting Systems of Oceangoing Ships

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Dimov Stojce Ilcev
Keyword(s):  
Remote Sensing ◽  
Satellite Communication ◽  
Pollution Monitoring ◽  
Automatic Identification ◽  
Identification System ◽  
Traffic Surveillance ◽  
Automatic Identification System ◽  
University Of Technology ◽  
Postgraduate Studies ◽  
Monitoring Service

This paper introduces the implementation of space remote sensing and detecting systems of oceangoing ships as an alternative to the Radio – Automatic Identification System (R-AIS), Satellite – Automatic Identification System (S-AIS), Long Range Identification and Tracking (LRIT), and other current vessel tracking systems. In this paper will be not included  a new project known as a Global Ship Tracking (GST) as an autonomous and discrete satellite network designed by the Space Science Centre (SSC) for research and postgraduate studies in Satellite Communication, Navigation and Surveillance (CNS) at Durban University of Technology (DUT). The ship detection from satellite remote sensing imagery system is a crucial application for maritime safety and security, which includes among others ship tracking, detecting and traffic surveillance, oil spill detection service, and discharge control, sea pollution monitoring, sea ice monitoring service, and protection against illegal fisheries activities. The establishment of a modern sea surface and ships monitoring system needs enhancement of the Satellite Synthetic Aperture Radar (SSAR) that is here discussed as a modern observation infrastructure integrated with Ships Surveillance and Detecting via SSAR TerraSAR-X Spacecraft, Ships Surveillance and Detecting via SSAR Radarsat Spacecraft and Vessels Detecting System (VDS) via SSAR.

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