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When the MV left the same berth and circled in the middle of the river, both GPS devices lost their signal


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The abnormal AIS and GPS readings in Port of Shanghai have been reported by the maritime industry.

An incident has been reported to the United States Coast Guard. The navigation center of this service receives GPS problem reports from maritime and other users around the world.

The report is published on the Navigation Center website, which states:

"After docking in Shanghai, the captain of an MV flying the Flag of the United States checked the ECDIS of AIS to see if their berth was free. Another ship on the berth seemed to be in the channel at a speed of 7 knots (kts) above the ground level (SOG), but then disappeared from AIS. A few minutes later, she returned to the dock, and then sailed again, 5 knots, 2 knots, 0 knots, in the channel, then returned to the dock, and left.

This mode has been repeated several times. It turned out that the other party's ship has always been very fast. Later, when the MV left the same berth and circled in the river, both GPS devices lost their signals, no positioning, no SOG, and various onboard equipment issued multiple alarms. The GPS signal will recover for one minute and then be lost again. It continues to the dock and continues. The GMDSS GPS knows the same thing. The captain suspects that this station has a GPS signal jammers. Vessel has checked all antenna connections - all connections are secure and dry. These units have no other issues.

Experts suggest that this situation is in line with a well documented GPS interference model. In 2009 and 2010, the Lighthouse Authority in the UK and Ireland recorded this for the first time during maritime interference tests. When encountering interference signals for the first time, the receiver usually initially considers them to be valid and generates dangerous misleading information. After a period of time, the receiver will be unable to calculate any type of position, and then it will be unable to report the position.

The reported events seem to be part of the ongoing problems in Shanghai. In addition to some anecdotal reports, analysts from the non-profit organization C4ADS observed the region and stated that the reports received by the Coast Guard "do not seem to be isolated incidents".

Because of the Automatic identification system (AIS), it is usually much easier to detect GPS interference in the commercial maritime sector than in other areas. GPS is the main sensor used by AIS to transmit location information to other ships and shore stations. AIS transmissions are also detected by satellites, and the information they provide is easily accessible. Earlier this year, C4ADS studied AIS transmissions in the Black Sea and other Russian waters, identified nearly 10000 deliberate maritime deception incidents, and linked them to efforts to protect Russian dignitaries.