Solar Cycle 24 may cause havoc for GPS farm instruments

Solar Cycle 24 will focus its force on precision agriculture instruments across North America this year.

Sunspots are on the rise. The peak of the last 11-year cycle of solar activity is happening now, bringing concerns about GPS reliability over the next couple years.

Sunspots, also called solar flares, appear as dark spots on the sun where solar temperatures drop. They usually come in groups of two sets of spots, with one set being positively charged and the other set negatively charged.

Sunspots last for several days or weeks, causing strong magnetic energy to be released towards the earth. These bursts of charged particles can interfere with our own magnetic fields. The added radiation can affect GPS satellites.

Solar flares cause geomagnetic storms manifested as brilliant aurora borealis. Green is a common colour, but red means intense storm action.

The Carrington flare of 1859 was the most intense solar storm recorded to date. The skies erupted in red, green, and purple auroras and could be seen in tropical latitudes such as Cuba and the Bahamas. It disrupted the worldwide telegraph system as spark discharges shocked telegraph operators and lit telegraph paper on fire.

In 1989, a major solar storm caused a nine-hour power outage in Quebec that affected six million people.

The charged particles from solar flares produce intense bursts of radio noise on the same frequency as GPS and can interfere with GPS reception. A flare could impede GPS signals for hours or days.

The cycles peak every 11 years or so. The 2001 cycle tailed off around 2003. In 2005 and 2006 there were a couple larger, unexpected flares.

Precision agriculture was just starting to take off during that peak activity and there were many outages.

One precision agriculture company had to scrap all its antenna/receivers and replace them with higher quality components. That season the expensive equipment didn’t perform well for producers, leaving them angry with dealers.

Some studies say the current Solar Maximum will be better than 2001 and some say 2012 will be 30 to 50 percent worse.

Sun spots can’t be predicted, but solar energy takes a couple of days to reach us, so we do get a two day heads up that it’s coming. There are solar weather websites and a sunspot app that can be downloaded to help take the surprise out of losing GPS accuracy.

Last year there were signs of minor GPS accuracy loss by farmers. Some experienced complete outages for hours and others had a lower than normal numbers of satellites. This caused lower accuracy and frustrating field conditions.

Many of the affected producers received a “High DOP” dilution of precision warning on their GPS units, which signified that the accuracy was not reliable enough to use automated steering systems.

Two substantial solar flare events in the first half of March demonstrated amazing aurora borealis, but without GPS units in the field, signal loss issues for farmers aren’t known.

I noticed an interesting trend while gathering data for Assiniboine Community College these past couple weeks. Data was collected with the differential correction WAAS signal turned on and off.

Normally, the locations with the correction signal turned on would be much more accurate than the data gathered without it. The opposite happened. With the signal on, data was sporadically scattered over an area twice as large as the area from the non-corrected data.

This could stem from the fact that the differential satellites (WAAS, Omnistar, StarFire) are at a higher orbit around the earth than regular GPS satellites.

Regular GPS satellites are much lower in orbit and travel much faster, hence the lower accuracy.

WAAS is a geostationary satellite orbiting with the earth’s rotation, at the same place in the sky all the time, delivering GPS correction down to inches. It’s also closer to the sun, which means it gets more solar energy earlier.

Solar flares also affect television reception, cellular towers and other communication devices, but being further away it might reduce the problems.

However, this means there may be accuracy or signal loss for the popular cellular modem RTK systems.

All precision agriculture will be affected if there is solar interference this year, from a producer’s automated steering to the consultant gathering field data for variable rate application maps.

Precise variable rate maps are critical for accurate chemical and fertilizer application. If GPS is unreliable, frustration will ensue.

What can you do?

Different antenna/receivers react differently to different solar activity. In some areas, a single band receiver may work better than a dual band, but the opposite may also be true.

There are many different types of antennas on the market, including omnidirectional, controlled radiation pattern and choke ring.

All gather and organize GPS signals differently and operate at varying levels on different days. In 2001, the omnidirectional antennas were often successfully replaced with controlled radiation pattern antennas.

First, make sure it is a solar flare that is causing your issues with GPS and then research the antenna/receiver options for your GPS system.

Try an upgraded antenna/receiver that is compatible with your system during a sunspot event before you commit to buying it.

Try upgrading your GPS signal to take advantage of more satellites (GNSS). This may also require a new antenna, so do your research now before seeding.

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