2019 GPS Week Rollover

2019 rolloverSome GPS receivers may malfunction on or after 6 April 2019 due to the GPS Week Rollover.

This is a known issue caused by the way that GPS used to handle the week element of the navigation signal. GPS used a 10 bit field to encode the week number in each GPS time message. This means that a maximum of 1024 weeks could be handled. This period is called an epoch. At the end of each epoch, the receiver resets the week number to zero and starts counting again.

The current epoch started on 1 August 1999. The next GPS rollover is 6 April 2019 when the receiver will revert to week number zero and start counting up to 1023 again.

Testing your receiver is easy with a LabSat 3.

1) Download the relevant test scenario for your LabSat system by filling in the form below.

2) Cold start your GPS receiver and replay the entire scenario.

If the date shown is April 7th 2019 and correctly counting up the time then all is fine for the 2019 rollover.

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However, that’s not necessarily the end of the story. Many receiver manufacturers will set the receiver to run for the full epoch from the date of their firmware. So if your receiver manufacturer has set the epoch start date in the middle of the epoch then it will run to the middle of the next epoch. Please contact the manufacturer to enquire if they have a firmware update for the 2019 rollover. If not check on the firmware date and, with our SatGen software, create a rollover scenario with a full epoch ahead and retest.

Multiband receivers accepting modern GPS signals that use 13-bit week encoding (L2C, L5) do not have the 1024 week epoch issue.