Understanding scintillation and its impact on GNSS and farming operations

As many industries, from precision agriculture and autonomy to marine, rely on GPS/GNSS technologies, the greater the need to understand the impacts that atmospheric changes like scintillation can have on positioning solutions. The best methods to protect your operations from scintillation are by leveraging precise point positioning (PPP) solutions, such as TerraStar and building positioning redundancy and resiliency to interference. 

What is scintillation and the ionosphere? 

The ionosphere is a layer of Earth’s atmosphere where high concentrations of ions and electrons react to the Sun’s radiation. During periods of high solar activity – like solar flares, solar storms or sunspots – the ionosphere’s density changes. These density changes can occur over a broad area or with variable intensity over more local areas.

As GNSS signals travel from satellites to equipment on Earth, the different atmospheric densities can delay or degrade the signal, causing position jumps, increased error and reduced availability of positioning solutions. When GNSS signals experience rapid fluctuations, it is called ionospheric scintillation. 

Scintillation can occur worldwide but is particularly active along the equator in South America and Southeast Asia. This problem impacts all types of GNSS receivers, regardless of the manufacturer or brand of positioning equipment used, and performance degrades as the severity of scintillation increases.

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Why is scintillation getting worse?

Scintillation occurs throughout the day, often in the evenings and throughout the year, increasing during the spring and fall equinoxes. However, there has been an increase in scintillation frequency and strength because of the current solar cycle. Our Sun goes through cycles every 11 years; solar cycle 25 began in 2019, and as we approach the peak, solar flare activity will increase in intensity and duration. 

What does the increase of scintillation mean for farming operations?

The decreased reliability of GNSS, when scintillation is present, can lead to machine guidance interruptions, potential for crop damage, and over/under application of inputs because of overlaps/gaps. Operations like farming that operate 24/7 require the highest level of positioning resiliency and redundancy to avoid downtime and inefficiency. For a seasonal industry with very limited time frames for each part of the crop lifecycle, scintillation can devastate an operation’s bottom line. 

The best means of protection against scintillation is being proactive in your positioning solution.

How to reduce the impact of scintillation 

Being proactive in your positioning solution by building redundancies is the best way to ensure continuous operations as much as possible. With limited operating windows, ensure your system is ready the next time scintillation strikes.

• More signals for more availability: PPP solutions like TerraStar leverage multi-constellation, multi-frequency (MCMF) GNSS signals from corrections generation through to the receiver’s positioning solution. 
  
  TerraStar PPP corrections are generated from a global network of reference stations to model and estimate errors. With corrections derived from a global network, there is a broader selection of signals to help identify and correct errors. 
  
  MCMF GNSS receivers are compatible with a greater number of satellite signals. With more signals, your system can better withstand disrupted GNSS signal tracking. Recent updates to receiver firmware provide further improvements to TerraStar PPP accuracy and availability during scintillation. 
  
  By using TerraStar-C PRO you get access to the most signals, greatest accuracy and fastest start-up time.
• Scheduling operations: While solar storms are not always predictable, regular occurrences of scintillation are. It often occurs in the evenings and increases during spring and fall equinoxes. Where possible, plan operations ahead so you can avoid times of high scintillation to lessen the impacts of ionospheric activity. View our forecast map to help with planning.
• Diverse sources of signals through TerraStar corrections: TerraStar PPP corrections are globally available and don’t rely on local base stations. Instead, corrections are generated from a global network of reference stations to model and estimate potential errors in your region. With corrections derived from a global network, there is a broader selection of signals to help identify and correct errors. This signal diversity makes TerraStar the most resilient correction source for operating in regions affected by scintillation and ensures that interruptions to positioning accuracy and availability caused by scintillation are minimised, reducing downtime. By using TerraStar-C PRO you get access to the most signals, greatest accuracy and fastest start-up time.
• Communication: Keep in touch with your local equipment dealer and stay updated on new GNSS advancements in precision farming. Watch for new information on TerraStar.net and sign up to be the first to know about new information on scintillation and product or service enhancements that can help you weather future space storms.