1. Announcement

Dear Customer,

We are writing to inform you of an upcoming change that will affect the continued operation of certain legacy systems currently in use.

1.1. Background

GPS time is represented as a week counter starting from 6 January 1980. Due to limitations in the GPS navigation message format, the week counter rolls over every 1024 weeks (approximately 19.7 years). These rollover events occurred in 1999 and most recently on 6 April 2019.

When the most recent rollover even happened in 2019, most modern receivers already had built-in mitigation to handle the event. However, older generations of GNSS receivers that were End of Life had limited or no mitigation, resulting in potentially outputting an invalid date.

Rather than solely relying on the GNSS receiver firmware, OXTS also implemented our own mitigation in our INS firmware, enabling our legacy products to continue operating correctly past the date at which the GNSS receiver firmware would have caused the week number to rollover and the date expire.

1.2. What is changing?

The OXTS firmware mitigation implemented for the 2019 GPS Week Rollover has a finite operational lifespan. That mitigation will expire in August 2026, after which affected systems will no longer be able to correctly interpret GPS date information.

1.3. Impact after August 2026

Once the mitigation expires:

• GPS date and time outputs will become invalid.
• While the system may continue to output correct navigation measurements, the timestamps for that data will be incorrect.
• Systems relying on GPS time will malfunction.

1.4. Why can this not be fixed?

• The impacted hardware platforms are legacy systems, ending production 10+ years ago.
• The underlying OXTS firmware architecture (RTBNS) reached end of life in 2020.
• As a result, no further firmware or software remediation is technically possible.

2. Affected Product(s)

If your system was originally purchased prior to 2016, it is likely to be affected. The full list of affected models is shown in the table below. If you are unsure whether your system will be affected, please get in contact.

3. Required Customer Actions

To avoid service disruption, customers should:

• Identify any systems still in operation utilising the affected products listed above.
• Plan for replacement or migration prior to August 2026.
• Consider replacing the legacy systems by taking advantage of our trade-in scheme https://www.oxts.com/solutions/inertial-navigation-solutions/trade-in-scheme/ 
• Contact us directly if you are unsure whether your system will be affected.

4. Contact Information

If you have any questions regarding this notice, please reach out to your account representative or contact us at:

OXTS Ltd.
Park Farm Business Centre
Middleton Stoney 
Oxfordshire 
OX25 4AL
United Kingdom

Phone: +44 (0) 1869 814 253
Email: support@oxts.com 
Support portal: https://support.oxts.com