Notice: GPS Week Number Rollover for equipment
We would like to announce that GPS week number rollover ＊ for equipment is to occur on some of our GPS’ on 4th August 2019.
The subject models are designed to turn the clock back 19.6 years (December 19, 1999), and will continue to work incorrectly under normal use, however there is no influence on positioning operation.
As the results, the following abnormalities occur in some equipment.
– The some date information will be displayed erroneous.
– The erroneous date will be output to external equipment.
For details, please see the 2.Notice and countermeasures below.
＊： The week number counter in GPS resets once every 1023 weeks, which is approximately 19.6 years. The week number counters for the GPS in the discontinued models below started their week count from the 19 December 1999. It is on the 4th August 2019 at 00:00 AM (UTC) that the week number counters rollover will occur.
1. Objective Equipment
AIS（JHS-180/182）
Inmarsat C（JUE-75A/75C）
GPS navigator（JLR-7700MKⅡ）
GPS receiver（JLR-4330/4330W/4331/4331W）
GPS compass（JLR-10/10T）
2. Notice and Countermeasures
The rollover day is on the 4th August 2019 at 00:00 AM (UTC).
| Equipment | Models | Subject Serial No. | Notice | Countermeasures |
| AIS | JHS-180 | All | Some log date information will be displayed erroneous. The erroneous date will be output to Aux port. | Replace with JHS-183 |
| JHS-182 | Up to BB51400＊1 | Replace with JHS-183 or Upgrade the software＊6 | ||
| Inmarsat C | JUE-75A/C | JUE-75 with optional GPS kit (6EZSC00031) | Some function of scheduled calling and position reporting will operate erroneous. | Connect the external GPS or replace with JUE-87 |
| GPS Navigator | JLR-7700MKⅡ | Up to KE47189＊2 | Note that time and date will go back to the starting date (December 19, 1999) when a master-reset of equipment or a battery replacement is carried out after rollover day. | When the time and date go back to the staring date, the equipment will return to normal operation by the following settings.Setting method of JLR-7700MkⅡ Setting method of JLR-4330,JLR-4330W, JLR-4331,JLR-4331W Setting method of JLR-10,JLR-10T |
| GPS Receiver | JLR-4330 | Up to KE54238＊3 | ||
| JLR-4330W | All | |||
| JLR-4331 | Up to KE50478＊4 | |||
| JLR-4331W | Up to KE51718＊5 | |||
| GPS Compass | JLR-10/10T | ALL |
＊1: Next rollover of BB51401 and after will be August 2025. Notice and countermeasures are same as this.
＊2: Next rollover of KE47190 and after will be May 2022. Notice and countermeasures are same as this.
＊3: Next rollover of KE54239 and after will be May 2022. Notice and countermeasures are same as this.
＊4: Next rollover of KE50479 and after will be May 2022. Notice and countermeasures are same as this.
＊5: Next rollover of KE51719 and after will be May 2022. Notice and countermeasures are same as this.
＊6: For the software update, the corresponding cost will be charged.
It is possible to support in August 2025 with this software to be released.
Source: JRC|ALPHATRON