GPS Turns 25
The United States-based global positioning system (GPS) constellation is celebrating an historic landmark in 2014, as it marks its 25th year of operation. Today, it is just one component of what is known today as the GNSS, or Global Navigation Satellite System.
“Currently the GPS system is very healthy, with 31 operational satellites and a replenishment program underway to replace the aging GPS Block IIA satellites,” notes Erik Ehn, business area director at Trimble. “In addition, with other GNSS systems (GLONASS, Galileo, and Beidou) and regional systems QZSS (Japan) being deployed, global use of GPS is very high.”
In a relative blip of time in the landscape of history, GPS has evolved from a curiosity to an absolute necessity for modern business. From developing complex algorithms for package deliveries to the app that tracks your jogging route, the world has come to rely deeply on accurate and consistent positioning data.
In agriculture, the potential benefits of georeferencing data was understood even before GPS, as Grant Lien will attest. Lien worked with development teams on what would become the Soilection system back in the early and mid-1980s, which utilized ground based radar systems to establish positioning. The goal at that time was to turn soil test data into variable-rate fertilizer prescriptions.
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Radar systems proved too inconsistent and labor intensive to fully commercialize, but when GPS became available, the proof of concept was already in place. In May of 2000, removal of selective availability, an error that the government purposely built into the signal to thwart potential illicit use of GPS, opened the door more widely for enhancement of technology using GPS.
GPS use continued to grow steadily, but the proliferation of automatic steering in the mid-2000s arguably made the most significant impact on GPS development. Demand for higher levels of accuracy among end users, and the standardization of steering technology on large equipment (coupled by a booming ag economy) generated a rush of accuracy and reliability-driven developments that have moved global positioning signals into the realm of “utility” along the lines of phone service, electricity and water.
“Over the last 25 years we have seen satellite-based enhancements become better than ever before, and in the future we can expect to see satellite based correction accuracies continue to advance and become closer to RTK accuracy, says Ehn. “We also anticipate that it will become easier for farmers to apply satellite-based receivers to every piece of equipment on the farm.”
“Moving forward, with the adoption of variable-rate technologies and other precision technology that requires higher accuracy positioning, we see customers wanting broader access to higher accuracy GPS corrections,” says Ryan Molitor, operations manager at Raven Industries. “You also see larger RTK networks with easier access for end user customers.”
Ongoing changes to GNSS technology, will provide plenty of challenges for manufacturers that want to make the most out of the positioning signals, notes Joe Brabec, chief technology officer at Topcon. “At the end of the day, what people want is accurate positioning that’s available 24/7,” says Brabec. “There are techniques you can employ to get higher accuracy, such as positioning transmitted via internet or the use of a fixed base station. We think that if you can achieve the desired accuracy without a base station and make it available through a subscription, end users will buy into that.”