Underwater Low-Frequency Magnetic Field Detection Based on <i>Rao</i>’s Sliding Threshold Method

This paper proposes a joint time–frequency analysis method that combines <i>Rao</i> detector with dynamic sliding thresholds to enhance the detection performance of electric source axial frequency magnetic field signals. For each signal-to-noise ratio (SNR) point, 1000 Monte Carlo simula...

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Main Authors: Yi Li, Jiawei Zhang
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Sensors
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Online Access:https://www.mdpi.com/1424-8220/25/11/3364
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author Yi Li
Jiawei Zhang
author_facet Yi Li
Jiawei Zhang
author_sort Yi Li
collection DOAJ
description This paper proposes a joint time–frequency analysis method that combines <i>Rao</i> detector with dynamic sliding thresholds to enhance the detection performance of electric source axial frequency magnetic field signals. For each signal-to-noise ratio (SNR) point, 1000 Monte Carlo simulations were independently conducted, with SNR ranging from 15 dB to −30 dB. The results show that the proposed method maintains high detection rates even at extremely low SNRs, achieving about 90% detection probability at −13 dB, significantly outperforming traditional energy detectors (with a threshold of 2 dB). Under conditions where the detection probability is ≥90% and the false alarm probability is 10<sup>−3</sup>, the SNR threshold for the <i>Rao</i> detector is reduced by 15 dB compared to energy detectors, greatly improving detection performance. Even at lower SNRs (−30 dB), the <i>Rao</i> detector still maintains a certain detection rate, while the detection rate of energy detectors rapidly drops to zero. Further analysis of the impact of different frequencies (1–5 Hz) and CPA distances (45–80 cm) on performance verifies the algorithm’s robustness and practicality in complex non-Gaussian noise environments. This method provides an effective technical solution for low SNR detection of ship axial frequency magnetic fields and has good potential for practical application.
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spelling doaj-art-567b2c947d2d48b5b29b6770e1858f8b2025-08-20T03:46:49ZengMDPI AGSensors1424-82202025-05-012511336410.3390/s25113364Underwater Low-Frequency Magnetic Field Detection Based on <i>Rao</i>’s Sliding Threshold MethodYi Li0Jiawei Zhang1Naval University of Engineering, Wuhan 430030, ChinaNaval University of Engineering, Wuhan 430030, ChinaThis paper proposes a joint time–frequency analysis method that combines <i>Rao</i> detector with dynamic sliding thresholds to enhance the detection performance of electric source axial frequency magnetic field signals. For each signal-to-noise ratio (SNR) point, 1000 Monte Carlo simulations were independently conducted, with SNR ranging from 15 dB to −30 dB. The results show that the proposed method maintains high detection rates even at extremely low SNRs, achieving about 90% detection probability at −13 dB, significantly outperforming traditional energy detectors (with a threshold of 2 dB). Under conditions where the detection probability is ≥90% and the false alarm probability is 10<sup>−3</sup>, the SNR threshold for the <i>Rao</i> detector is reduced by 15 dB compared to energy detectors, greatly improving detection performance. Even at lower SNRs (−30 dB), the <i>Rao</i> detector still maintains a certain detection rate, while the detection rate of energy detectors rapidly drops to zero. Further analysis of the impact of different frequencies (1–5 Hz) and CPA distances (45–80 cm) on performance verifies the algorithm’s robustness and practicality in complex non-Gaussian noise environments. This method provides an effective technical solution for low SNR detection of ship axial frequency magnetic fields and has good potential for practical application.https://www.mdpi.com/1424-8220/25/11/3364shipaxial frequency magnetic field<i>Rao</i> detectornon-Gaussian noisesliding threshold
spellingShingle Yi Li
Jiawei Zhang
Underwater Low-Frequency Magnetic Field Detection Based on <i>Rao</i>’s Sliding Threshold Method
Sensors
ship
axial frequency magnetic field
<i>Rao</i> detector
non-Gaussian noise
sliding threshold
title Underwater Low-Frequency Magnetic Field Detection Based on <i>Rao</i>’s Sliding Threshold Method
title_full Underwater Low-Frequency Magnetic Field Detection Based on <i>Rao</i>’s Sliding Threshold Method
title_fullStr Underwater Low-Frequency Magnetic Field Detection Based on <i>Rao</i>’s Sliding Threshold Method
title_full_unstemmed Underwater Low-Frequency Magnetic Field Detection Based on <i>Rao</i>’s Sliding Threshold Method
title_short Underwater Low-Frequency Magnetic Field Detection Based on <i>Rao</i>’s Sliding Threshold Method
title_sort underwater low frequency magnetic field detection based on i rao i s sliding threshold method
topic ship
axial frequency magnetic field
<i>Rao</i> detector
non-Gaussian noise
sliding threshold
url https://www.mdpi.com/1424-8220/25/11/3364
work_keys_str_mv AT yili underwaterlowfrequencymagneticfielddetectionbasedoniraoisslidingthresholdmethod
AT jiaweizhang underwaterlowfrequencymagneticfielddetectionbasedoniraoisslidingthresholdmethod