GPS Time Rollover Awareness

WHAT YOU NEED TO KNOW

Connectivity allows you to access up-to-the-minute, accurate information anytime, anywhere—and use it to make decisions that boost productivity, lower costs, simplify maintenance, and improve safety and security on your job site. We understand how important this data is to your operation. Unfortunately, we have recently learned about an issue impacting software inside certain navigation system devices in relation to GPS time rollover occurrences.

There is a problem with the time conversion software inside certain navigation system devices. Cat® Product Link, Trimble, Ag Leader, Reichhardt, Raven, Topcon, and other navigation system devices use GPS satellites to provide both location and time. These devices leverage an internal chip that interprets the date code from the GPS satellite. The satellites provide time data using a counter that represents the number of weeks from a set reference date. This timestamp has a maximum of 1024 weeks before it rolls over to zero, which represents the original reference date. Without intervention, when this happens, the software will not correctly interpret the timestamp. The effects to you could range from devices sending messages stamped with an incorrect date to not sending GPS locations or other data at all. Devices might also fail to provide geo-fence alters, appear as non-reporting, show improper asset utilization, or not provide a location. No impact to machine operation, grade control, or payload functionality is expected as a result of the GPS Time Rollover Occurrence.

An onboard over-the-wire software flash at the asset location may successfully resolve the issue. Our Technology Specialists or Field Service Department will contact you in the very near future to schedule the software update. In the meantime, please review the Q&A section below for more information.


Q:  What is the issue?

A:  The signal from GPS satellites will roll over from week 1023 to week 0 on April 7, 2019. This could cause your receiver to think it is 1999 (the first time this happened) or even 1980 (the start of GPS).

There is quite a bit of information on the internet about this issue. Here are links to a few articles if you’d like more information:

Q: How will this affect my auto-steer systems?

A:  That’s not clearly defined. The worst case would be that the GPS receiver stops working altogether; however, that’s unlikely. But there’s a chance the receiver will revert back to 1999 or 1980, which could affect its accuracy. Or a customer could see no change in operation and life will be great.

Of note, this issue may not pop up on April 6th or 7th. GPS receivers built after the first rollover in 1999 generally have software to extend the event for months or even years.

Q:  How can I prevent the problem?

A:  Our GPS suppliers across the board have recommended updating your receiver firmware. While this is a good idea, there are side-effects and “gotchas.” First, we need to be careful to back up all system data before updating. This data includes field boundaries, A-B lines, populations, yield data, etc. Anything that you may want in the future needs to be backed up. Second, some receivers cannot just be updated to the latest version of firmware. They need to advance one revision at a time, which can be tedious.

We recommend you call your local Butler Machinery Service Department and have a Technician come out to update your receivers. Charges will apply. Do not wait until the day before you want to plant to call. We will handle calls in the order we receive them.

Q: How will this affect my machine control systems?

A:  That’s not clearly defined. The worst case would be that the GPS receiver stops working altogether; however, that’s unlikely. But there’s a chance the receiver will revert back to 1999 or 1980, which could affect its accuracy. Or a customer could see no change in operation and life will be great.

Of note, this issue may not pop up on April 6th or 7th. GPS receivers built after the first rollover in 1999 generally have software to extend the event for months or even years.

  • Receivers
    Trimble Construction has assured us that any receiver made since 1999 will not have an issue with the week rollover. If you do see problems, we may have to update the firmware on your receiver. There are a few older models that could be affected.
  • Modems
    Trimble has determined that the GPS Week Number Rollover will affect SNM940 modems that are reporting into VisionLink software. These require updates of firmware, which Trimble will push over the air to your modem automatically starting on March 29, 2019. For devices that require an update, please make sure that the telematics device is “turned on” to receive the firmware update.

Devices must complete the firmware upgrade for continued operation before WNRO. Devices that do not have the firmware updated by this time will stop reporting into VisionLink, resuming only when the device firmware is upgraded.