GPS week number rollover may effect the GPS receiver’s ability to display date correctly. Time and position is normally not affected. Any GPS receiver must have internal software capable of handling the GPS week number rollover. For newer GPS receivers this is normally already in place. However, after the rollover has occurred a restart of the GPS equipment may be necessary. Older receivers may need a software upgrade or must be replaced by a newer model.

As far as possible FURUNO offers software updates for older versions of GPS receivers to handle GPS week number rollover. Should software upgrade not be possible we offer replacement models. Most often the antenna cables can be reused and we strive to allow refit without changes to cutouts.

Upcoming GPS week number rollover: 20. December 2020

The following Furuno instruments may be affected:

  • Furuno AIS: FA-100/R
  • Furuno Inmarsat C stasjon: Felcom-15
  • Furuno Inmarsat C stasjon: Felcom-16
  • Furuno GPS GP-310B (non-IMO)


Recommended action:

  1. Check whether you have instruments that may be affected
  2. When onboard service is required please contact us at and we will coordinate your service


Overview of future GPS week number rollover.

Please find an overview of future GPS week number rollover and Furuno instruments that may be affected:



​Data exchange will not be affected and targets will be presented as normal. However, the date will be incorrect for the following:​

  • Presentation of GPS date
  • Presentation of "Own Ship" data​
  • Dates for send/receive, alarm and on/off logs​

For the FA-100 it is not possible to offer software upgrade to remedy the effects of the upcoming week number rollover. Replacment will be necessary. Our replacement model is Furuno AIS FA-170. Provided in good condition, the antenna cable from the FA-100 can be reused.



IMPORTANT: Felcom-15 may be used to distribute GPS information to the GMDSS solution’ s VHF and MF/HF. If GPS is connected to Radio equipment as part of the GMDSS, a wrong date will violate the IMO regulation SOLAS IV/13.8, IV/18.

Furuno Felcom-15
For the Felcom-15 the GPS module is an option that in many cases is installed for the possibility to distribute GPS information to the GMDSS’s solution’s VHFs and MF/HFs. However, the Felcom-15 does not necessarily have the GPS module installed. This is easily checked by running the self test procedure described further down.

For Felcom-15 with early serial numbers of the GPS module installed, replacement will be necessary. Alternatively, the Felcom-15 and the GMDSS solution may receive GPS data from an external GPS.


Furuno Felcom-16
For the Felcom-16 the GPS module is integrated from factory. For models with serial no. below 3534-2756 replacement will be necessary.  


To determine whether your Felcom-15 has a GPS core module installed, run the self test.
The GPS test of the self test returns one of three possible values:

  • GPS ** : a GPS core module is not installed. SW upgrade related to GPS week number rollover is therefor not required.
  • GPS OK: a GPS core module is installed. Serial no. and software version need to be checked. 
  • GPS NG: a GPS core module is installed, but there is some deficiency. Faulty situation must be corrected and serial no. and software version need to cheked.


Procedure for self test, from the Operation Manual;

Check the DCE versjon to determine whether your Felcom-15/16 is affected by the next GPS week number rollover.

Dependent on serial no. of your Felcom-15 it will have either DCE version 03 or 05. DCE version is at all times displayed in the lower left corner of the Felcom-15 display.

For Felcom-15 models with DCE version 03,  update is required before rollover date 20. Dec. 2020.
For Felcom-15 models with DCE version 05, update is required before rollover date 02. Jan. 2022.


You can also check your exact software version of your Felcom 15/16
To determine whether you have the latest update required to handle the upcoming rollover, run the self test and then the SW version check command.

After the self test, press [CTRL] and type FELCOM and the exact sw version will be displayed. For the earliest models you may have to press [Fn] [Ctrl] and type FELCOM.

Command for sw version check, from the Operation Manual: