One of the most accurate GPS-based location systems in the world isn’t a hyper-secret military technology or a top-of-the-line scientific device – it’s John Deere’s RTK network, a dual-band GPS system that lets farmers track their planting, harvesting and more to an accuracy of less than an inch.
“It’s one of the most difficult and exciting programs that Deere’s ever done,” according to Terry Pickett, manager of advanced engineering at the company’s Intelligent Solutions Group.
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The technology is important because everything from tilling to planting to irrigation to harvesting is better and easier when farmers have a more precise way to track their position – crops can be distributed more evenly across a field, seeds planted at exactly the correct depth and position to maximize yield.
Dual-frequency GPS makes for greater accuracy, thanks to a better ability to correct errors introduced by atmospheric interference. Monitoring the difference between delays in the two frequencies lets operators “calculate out” the interference for a much more accurate positional reading.
“It’s what’s called a refraction-corrected measurement,” said Fred Nelson, principal engineer at the ISG.
The system works by pairing a network of base stations – which have a known location – with the GPS receivers in the cabs of the company’s machines. The difference between the signals received at the base stations and the cabs can be used as a coefficient to correct for the aforementioned ionospheric distortion.
But farmers face tough conditions beyond simple accuracy issues – the environment these systems work in is, in some ways, more demanding than that for military hardware, according to the Deere engineers.
While military gear has to be rated to work in extreme conditions, it typically has a shorter required service life. That’s not the case for farming equipment, which might have to work for thousands of hours a year for decades.
“In many ways, our mission life is long enough that it’s really difficult to make a system last,” said Pritchett.
This is part of the reason why Deere has retained a high degree of control over almost every aspect of its increasingly sophisticated technology stack – the software is all in-house and proprietary, and Nelson and Pickett say Deere is the only industrial company in the world that makes its own GPS ASICs, at least as far as they are aware.
Deere clearly believes it’s got a major technological lead over competitors. At its test farm in Bondurant, Iowa, two huge garages out of three are completely closed to visitors, and a PR chaperone simply opts for using Mi-Fi instead of trying to get us on to the tightly controlled local wireless network.
It’s difficult to argue that John Deere’s ISG hasn’t made farming a lot more sophisticated than the popular imagination of agriculture. The obsession with precision is everywhere – water sprayers correct for rotation speed when making turns, to ensure that soil at the inside of the curve receives precisely the same amount of water as soil at the outside; nutrient and moisture information can be precisely tracked, down to the square inch, and correlated against past yield data.
And the biggest difference, according to the Deere engineers, is that this simply makes life easier for the farmer of today, compared to his or her predecessors.
“Your options are a lot more open when you’re accurate,” said Pritchett.