The present work proposed a method for match SAR and AIS data to detect vessels carrying out suspicious activity in the Ivorian EEZ. Two superposition methods, detected AIS and SAR data, based on point-to-point associ...The present work proposed a method for match SAR and AIS data to detect vessels carrying out suspicious activity in the Ivorian EEZ. Two superposition methods, detected AIS and SAR data, based on point-to-point association on the one hand and point-to-line on the other hand, were used to detect suspicious vessels in Ivorian marine waters. The results showed that most vessels detected in the Ivorian EEZ do not declare their positions to avoid being spotted. These funds are likely to practice illegal, undeclared and unregulated fishing (INN fishing). This clandestine activity is very recurrent in Ivorian waters. This is illustrated by the number of suspicious vessels detected by SAR radar imagery which is greater compared to declared or authorized vessels.展开更多
Azimuth ambiguities （ghost targets） discrimination is of great interest with the development of a synthet- ic aperture radar （SAR）. And the azimuth ambiguities are often mistaken as actual targets and cause false ...Azimuth ambiguities （ghost targets） discrimination is of great interest with the development of a synthet- ic aperture radar （SAR）. And the azimuth ambiguities are often mistaken as actual targets and cause false alarms. For actual targets, HV channel signals acquired by a fully polarimetric SAR are approximately equal to a VH channel in magnitude and phase, i.e., the reciprocity theorem applies, but shifted in phase about ±π for the first-order azimuth ambiguities. Exploiting this physical behavior, the real part of the product of the two cross-polarized channels, i.e. （SHVSVH）, hereafter called A12r, is employed as a new parameter for a target detection at sea. Compared with other parameters, the contrast of A12r image between a target and the surrounding sea surface will be obviously increased when A12r image is processed by mean filtering algo- rithm. Here, in order to detect target with constant false-alarm rates （CFARs）, an analytical expression for the probability density function （pdf） ofA12r is derived based on the complexWishart-distribution. Because a value of A12r is greater/less than 0 for real target/its azimuth ambiguities, the first-order azimuth ambiguities can be completely removed by this A12r-based CFAR technology. Experiments accomplished over C-band RADARSAT-2 fully polarimetric imageries confirm the validity.展开更多
文摘The present work proposed a method for match SAR and AIS data to detect vessels carrying out suspicious activity in the Ivorian EEZ. Two superposition methods, detected AIS and SAR data, based on point-to-point association on the one hand and point-to-line on the other hand, were used to detect suspicious vessels in Ivorian marine waters. The results showed that most vessels detected in the Ivorian EEZ do not declare their positions to avoid being spotted. These funds are likely to practice illegal, undeclared and unregulated fishing (INN fishing). This clandestine activity is very recurrent in Ivorian waters. This is illustrated by the number of suspicious vessels detected by SAR radar imagery which is greater compared to declared or authorized vessels.
基金The National Natural Science Foundation of China under contract Nos 41376179 and 41106153
文摘Azimuth ambiguities （ghost targets） discrimination is of great interest with the development of a synthet- ic aperture radar （SAR）. And the azimuth ambiguities are often mistaken as actual targets and cause false alarms. For actual targets, HV channel signals acquired by a fully polarimetric SAR are approximately equal to a VH channel in magnitude and phase, i.e., the reciprocity theorem applies, but shifted in phase about ±π for the first-order azimuth ambiguities. Exploiting this physical behavior, the real part of the product of the two cross-polarized channels, i.e. （SHVSVH）, hereafter called A12r, is employed as a new parameter for a target detection at sea. Compared with other parameters, the contrast of A12r image between a target and the surrounding sea surface will be obviously increased when A12r image is processed by mean filtering algo- rithm. Here, in order to detect target with constant false-alarm rates （CFARs）, an analytical expression for the probability density function （pdf） ofA12r is derived based on the complexWishart-distribution. Because a value of A12r is greater/less than 0 for real target/its azimuth ambiguities, the first-order azimuth ambiguities can be completely removed by this A12r-based CFAR technology. Experiments accomplished over C-band RADARSAT-2 fully polarimetric imageries confirm the validity.
