DEEPSEA WORLD

Dear Valued Customers,

We thank you very much for your trust and continued support. This is to notify you that a GPS week number rollover may occur to certain GPS receivers that we supply. We would like to take this opportunity to inform you of the countermeasures that should be taken to remedy this situation. Meanwhile, you will be directly notified of this through our representative in your area.

The nature of the problem:
On the 12th of December 2010, the date information contained within certain GPS receivers (listed below) will roll back to the 28th of April 1991. This is called "GPS week number rollover".

Although this does not affect position data, the date information on which the position is computed will be incorrect (the time information is not affected). Namely, if the GPS receiver is used only for obtaining position data, this will not pose a problem at all, but if the date information is utilized or the GPS receiver is integrated in the data-collecting system, a problem will arise due to incorrect date information.

Why GPS counts week number rollover occurs:
The GPS week number rollover occurs every 1,024 weeks -- about once every 20 years. The GPS system calculates date by counting the number of weeks in the cycle of 1,023 weeks. On the eve of the beginning of the1,024th week, the GPS week "counter" will roll back to zero weeks (Time Scale Origin). As a result, some GPS receivers may process satellite data incorrectly and display inaccurate date information.

Case study of a system affected by GPS week number rollover:
If an affected GPS receiver was utilized in the following system configuration, the systems date information fed from the GPS receiver would be incorrect. However, it is presumed to be rare that the GPS receivers in question are used in such system configurations.

• When a GMDSS radio system with the GPS receiver in question interfaced transmits DSC signals, such as distress alert, the date information on which the distress alert is transmitted may be incorrectly processed. N.B., GPS receiver to be incorporated in the GMDSS radio system has to be type-approved by the authority, and thus it is, presumably, a rare case that the GPS receiver in question is incorporated in a GMDSS radio system.
• Ship Security and Alert System (SSAS) transmits a distress alert when the vessel is under attack from a hostile party, such as pirates and terrorists. In this case, the date information on which the distress alert is transmitted may be incorrectly processed. N.B., FELCOM 11 Inmarsat-C Ship Earth Station, which may be affected by the problem, is rarely utilized in SSAS.
• In a Vessel Monitoring System (VMS), the position data of the vessel is automatically reported, and the date information within the report may be incorrectly processed. N.B., If a FELCOM 11 is utilized in VMS, the problem may occur, but it is considered a rare case.
• If the GPS receiver in question is interfaced with an Electronic Chart Display and Information System (ECDIS) and other equipment that is used to display route information, the problem may occur. N.B., It is presumed, again, to be a rare case for the GPS receiver in question to be interfaced with ECDIS.
• A Voyage Data Recorder (VDR) that receives date information from the GPS receiver in question may record the date information incorrectly. N.B., It is presumed, again, to be a rare case for the GPS receiver in question to be interfaced with a VDR. Any other equipment or system that receives date information from the GPS receiver in question may be affected by this problem.

Countermeasures to be taken:
Countermeasures to be taken against the problem stemmed from GPS week number rollover are stated below:

Please note that in order to resolve the problem, it is required that engineering work be conducted by a skilled technician to open the equipment and replace the GPS core inside. Please also note that you will be charged for the engineering work required. Please consult with our distributors/dealers for further details on this.

We apologize for any inconvenience caused and appreciate your understanding.

Yours Sincerely,