![]() ![]() 1 year) or longer than human lifespans by several orders of magnitude (e.g. Date counters should either be so short that engineers mustdesign rollovers into the devices (e.g. NetModule has implemented a bug fix and corrected the time information in the NMEA data. It gives 13 bit to the message at least, making the counters roll over every 157 years instead of every 20. However, some GNSS chipsets show an invalid time from November 2019. We are now nearing the end of the second epoch, which will fall on the 6th April 2019.Īnalysis for NetModule Routers showed, that time and location information provided by our GNSS enabled Routers are not affected by the Rollover effect 6th April 2019. At the end of each epoch of 1,024 weeks, the receiver resets the week number to zero and starts counting again.The first GPS satellites went live on 6th January 1980, meaning that the first epoch of GPS time lasted until 21st August 1999. Each of these periods is known in GPS terms as an “epoch”. WNRO is that moment when the GPS week number switches from 1023 to 0 (more information on this particular event in the Support Bulletin below). GPS used a 10-bit field to encode the week number in each GPS time message, which means that a maximum of 1,024 weeks (19.7 years), could be handled. November 2019 October 2019 September 2019 August 2019 June 20 March 2019 February 2019 January 2019. The newer message types (CNAV and MNAV) use 13-bit binary numbers to represent the GPS week number, so the issue should not occur in the future when more receivers are using the newer GPS signals.The Week Rollover Problem is a known issue caused by the way that GPS used to handle the week element of the data that forms an essential part of the navigation signal. GPS is currently undergoing a modernization program to upgrade the signals with new modulation and data message structures. The week counter then reset to zero, and it has been recounting ever since. The 1024 weeks counter ran out and rolled over on August 21, 1999. This limits the range of the week number to 0 1023, or 1024 total weeks. From Wialon side, we’re unable to prepare for WNRO since we can’t predict which trackers will be affected and which data they will transmit to Wialon. Because the maximum value of a 10-bit number in binary is 1111111111, or 1024 in base-10, every 1024 weeks (or 19.7 years) this number resets, or rolls over. However, the field that contains the week number is a 10-bit binary number. At a minimum, we recommend consulting your GPS device manufacturer to confirm that the issue has been fully tested and will not occur. In these cases, we want to verify that an issue will not occur. GPS device is a core component of a critical timing system – ask yourself – what is the impact to my system if the GPS receiver stopped operating or put out wrong GPS or UTC information.GPS device has been fielded for more than 10-15 years without firmware updates.You should be concerned, though, if either of the following applies: Should you be concerned?īecause this it is the second time the GPS week rollover will occur, many receiver manufacturers have prepared for it, and newer receivers will continue to operate without issue. Some GPS trackers that utilise the date and time function, may not be able to cope. As we approach the end of the second epoch, which will fall on 6th April 2019, we may well see problems caused by the rollover. The first epoch started when GPS was launched in January 1980 hence the first epoch of GPS time came to an end on 21st August 1999. At the end of each epoch the receiver resets the week number to zero and starts counting again – a new epoch begins. Each 19.7 year period is known in GPS terms as an “epoch”. A binary 10-bit word can represent a maximum of 1,024 weeks, which is approximately 19.7 years. The week number is encoded into the data stream by a 10-bit field. Because of its low cost and universal availability, The Global Positioning System (GPS) has become the standard time keeper for many commercial users across the globe. ![]() The potential problem revolves around the way that GPS handles the week element of the data that forms part of the navigation signal. GPS Week Number Roll Over (WNRO) An accurate accounting of time is of critical importance to nearly every modern organization. On April,6 or after it some GPS trackers may start to perform strangely. This day will mark a special rollover of the GPS week number, or WNRO, that helps receivers tell time more precisely. Week Number Rollover Starting on November 3, 2019, mobile devices manufactured between 2006 2016 may have their GPS accuracy impacted due to Global Positioning Service (GPS) Rollover. Fortunately, the April Rollover didn’t have much incident and so we’re expecting more of the same next month. If you use GPS trackers in your business, April 6, 2019, is probably a date worth marking in advance. So there will be a second round which will happen on November 3, 2019, at 12:00 AM UTC. ![]()
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