Stop Solar Flares from Bringing Construction to a Standstill
BY AsphaltPro Staff
About every 11 years, the world experiences a peak in solar activity with the next maximum predicted between 2024 and 2026.
During these periods of heightened solar activity, the resulting ionospheric disruptions may negatively impact the quality of global navigation satellite system (GNSS) signals and degrade positioning accuracy. That’s why Trimble, Westminster, Colorado, has developed a new technology to mitigate GNSS signal interruptions caused by ionospheric activity: IonoGuard™.
Although the effects of ionospheric disruption are typically minimal or isolated to certain geographic regions, according to Trimble, “it is during the peak where global disruptions can bring construction and mining operations to a costly halt when they are dependent on precise positioning.”
Trimble’s new IonoGuard technology aims to mitigate ionospheric disruptions in positioning and navigation by minimizing performance impacts caused by scintillation or signal noise. This graph shows the extent to which IonoGuard was able to improve positional accuracy at a site in Sweden.
Planning for a High Peak
The upcoming peak is the fourth solar maximum Ed Norse, portfolio manager of Trimble’s GNSS original equipment manufacturer (OEM) modules, has experienced since joining the industry. “The first one I experienced in the late ’80s was quite large,” he said. “It was significant enough to shut down some electrical grids.”
The next two peaks, in 2001 and 2014, were relatively mild in comparison. “We don’t expect the upcoming peak to be as bad as [1989], but it does look as though this peak will be larger than the last two,” Norse said. If that’s the case, it could create problems not only for the areas familiar with ionospheric disruption—latitudes along the equator and near the poles—but also mid-latitudes such as the continental United States and Europe. “It’s possible some customers in the mid-latitudes who require the highest possible accuracy could experience problems that may occasionally shut down their operations.”
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This can occur during a period of high sunspot activity, which usually lasts for a few days. “However, the problem is not constant during those days,” Norse said, and may last anywhere from a few minutes to a few hours.
Not only were the past couple peaks less intense than what’s anticipated for 2025, but there were also far fewer customers relying on Trimble’s highest-precision positioning technique, real-time kinematic (RTK) GPS. “Our number of RTK users has doubled every decade,” Norse said. “The levels were lower and we had fewer users [in 2014], but the applications then didn’t require as high of accuracy as they do today.”
For example, he added, “One of our biggest problems right now is running autonomous trucks in mines in South America. We weren’t running trucks autonomously 11 years ago, but autonomy is a big thing now and that requires centimeter level accuracy.”
How the Sun Cycle Impacts Positioning Accuracy
The solar cycle is a periodic variation in the Sun’s activity, measured by changes in the number of sunspots on the Sun’s surface. Sunspots are regions of the sun with temporarily reduced surface temperature, caused by active magnetic flux reducing convection.
Sunspots can eject material from the sun, known as Coronal Mass Ejection. If the material is ejected toward Earth, this can sometimes be observed as the Northern (or Southern) lights—in addition to impacting GNSS performance. During more intense storms, the Northern lights can extend to the continental United States, as can the impact on GNSS signals at these lower latitudes.
“The more sunspots, the more areas with magnetic activity,” Trimble writes in an IonoGuard technical paper. These areas can eject particles, which may be carried to Earth. “As more particles hit earth, the layer of atmosphere known as the ionosphere becomes more charged, and the GNSS signal delay resulting from the ionosphere increases.”
“In general, GPS and GNSS rely on very faint signals coming through the atmosphere,” Norse said. “We need a good signal from at least four satellites, and if the signal is affected in any way, that can affect our positional accuracy.”
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Peaks Pose Challenges
According to Norse the degradation to positional accuracy as a result of ionospheric disruption can reach as much as a meter. “In some applications, like a car navigation system, that might still be okay,” he said. “But for an operation requiring centimeter accuracy, a degradation of even a couple centimeters is a deal-breaker.”
Trimble supplies its users with an accuracy estimate so the customer knows what level of accuracy under which they are currently operating. “Then, they can decide whether or not they want to proceed,” Norse said.
For example, surveying operations require accuracy to 1 or 2 centimeters. “Depending on the application, grading equipment might need blade accuracy of 1 to 3 centimeters,” Norse said. “Compaction is an application growing in popularity that also requires centimeter accuracy.”
“We’ve already seen some issues with construction operations in Alaska and grading applications in Brazil,” Norse said. “Although we’ve seen some small levels of ionospheric disruption in the mid-latitudes already, it hasn’t been enough to shut down operations.”
So far, the applications most affected by the upcoming peak include mining and agriculture along the equator and northern Canada. “Mining activities running autonomous machines and mining applications in general are a high-cost application where downtime is very expensive,” Norse said. “If a mine goes down for even a couple hours, that could be hundreds of thousands of dollars lost.”
And, unfortunately, ionospheric disturbances are difficult to predict and, therefore, difficult to schedule around. Although winter is generally worse than summer and nighttime is generally worse than day, Norse said “there will be good days and bad days, with the number of bad days increasing as we reach the peak—and there’s no way to know when these bad days will occur.”
Enter IonoGuard
Although Trimble has been adjusting its technology in regards to the solar cycle for decades, the company began to prepare for the 2025 peak in earnest five years ago. Trimble installed raw radio frequency (RF) recorders at multiple equatorial and high latitude locations to capture both regular seasonal ionospheric activity in addition to activity during some major solar storm events.
The company then replayed this raw data to test the effectiveness of its new signal processing techniques and RTK algorithms before loading this updated firmware into onsite receivers for real time evaluation—to much success.
“For example, in a scenario with 10 or 20 centimeters of error, IonoGuard can generally get the accuracy back to 1 to 2 centimeters,” Norse said. “We had customers in northern Canada and Alaska running beta versions of IonoGuard, and it greatly helped.”
Trimble also has established a global ionospheric measurement network (gnssplanning.com), which allows users to see current ionospheric disturbance and plan ahead for times when higher disturbance is anticipated.
According to Trimble, multipath, jamming and other factors can cause similar outcomes as ionospheric disturbances. Trimble’s IonoGuard firmware features a traffic light system of green, yellow, orange and red icons to indicate the current level of ionosphere disturbance that the RTK base station is experiencing on each satellite, so users can more easily pinpoint if that might be the cause of any issues. “If that seems to be the case, please download the latest firmware to all roving receivers,” Norse said. “If the problem persists, there’s something else that needs troubleshooting, such as a problem with the base station, a bad cable, etc.”
“Ionospheric disturbance doesn’t affect all satellites at once,” Norse said, adding that the receiver web interface will show which satellites are most affected. “IonoGuard will automatically de-weight the satellites most affected compared to the satellites that are not passing through the problem area.”
According to Norse, Trimble plans to continue honing IonoGuard leading up to the 2025 solar maximum. “We were under time pressure to get the technology out because customers are already having problems,” he said. IonoGuard was released in November 2023 as a free downloadable firmware update for Trimble GNSS receivers utilizing the ProPoint® GNSS positioning engine. “Once affected customers install the new firmware and test what IonoGuard can do, they’ll see that it results in a significant improvement.”