FURUNO GPS week number rolloverGepostet am
Important notice to our customers who use FURUNO GPS products for marine use that are affected by GPS week number rollover.
We thank you very much for your trust in and continued support for our products and services.
It is regretful to announce that there is a possibility that some of our GPS products (please see the list below) may face GPS errors after the 17th of March 2019, due to the problem of GPS week number rollover. If you happened to spot any errors on the equipment listed below, we would like you to take the following countermeasures to resolve the problem. If the problem persisted after having taken the countermeasures, please consult with our sales representative closest to your location. We sincerely apologize for all the inconveniences caused.
1.List of equipment that may be affected by the GPS week number rollover
Rollover Occurrence Date: 2019/03/17
|Type of Equipment||Model|
|Inmarsat-C mobile earth station||FELCOM12 / FELCOM12-ALC|
|Radar plotter sounder||RS-1000A / RS-1000C / FRS-1000A / FRS-1000B / FRS-1000C|
|Color video plotter||GD-280 / GD-380 / GD-680|
|GPS plotter||GP-1600 / GP-1810 / GP-1610C / GP-1650 / GP-1850 / GP-280 / GP-3210 / GP-380 / GP-680|
|GPS/plotter/sounder||GP-1600F / GP-1610CF / GP-1650F / GP-1810F / GP-1850F|
|DGPS plotter||GP-1650D / GP-1850D|
|DGPS plotter/sounder||GP-1650DF / GP-1850DF|
|GPS receiver||GP-310B (serial no. 3453-4870 to 5686)|
NOTE: The date specified above is the date in which week number rollover occurs in our products listed above, and the date is independent from the one announced by the US Department of Homeland Security, namely, the 6th of April 2019, which is the date when GPS week number rollover occurs in the GPS as a system per se. The difference stems from different initial dates of counting week between GPS system and the GPS chipset used in our products.
2.Natures of the error and its cause
The GPS system is synchronized to a different time scale than Coordinated Universal Time (UTC) and calculates time by counting the number of weeks up to 1,023rd week.After week 1,023, the week number count is reset to zero. This is called “GPS week number rollover”. Subsequently, the erroneous date information on the GPS receiver clock may result in instability in positioning, causing position errors, including failure of GPS position acquisition, etc.
3.Procedure for checking the integrity of the equipment and counter measures to be taken
Please carry out the following counter measures:
- Since the nature of the problem of “GPS week number roll-over” is the erroneous date information on the receiver clock, the equipment that does not require date information would be unaffected by the problem in question. If, by any chance, the positioning performance became instable, you would be able to resolve the problem of positioning integrity by cold-starting the equipment through the operating menu. Please note, however, that even though you regain the GPS position acquisition, the date information cannot be restored merely by cold-starting.
- If the positioning integrity is not restored after cold start, the problem may stem from the failure of the equipment, not from GPS week number roll-over. If such is the case, please consult with our sales representative closest to your location.
- If you wish to restore the date information, you will need to replace the GPS receiver within the equipment for value. Also, please note that the above list of equipment includes some models whose maintenance service provision period has been expired.
If the GPS product is interfaced with any of the following equipment and systems, the countermeasures would have to be taken, for the date information is utilized by the interfaced equipment and systems.
- GMDSS radio installation, incl. internal GNSS receiver of Inmarsat-C terminal
- Ship Security Alert System (SSAS)
- Vessel Monitoring System (VMS)
- Equipment that displays route information such as ECDIS
- Voyage Data Recorder (VDR)
- Automatic Identification System (AIS)
- Other equipment and systems that utilizes the date information from GPS receiver clock
For further information and consultation, please contact US.