Smart "Ears" To The Sky
This season's GPS receivers offer more convenience and accuracy to users at both ends of the adoption spectrum.
September 10, 2008
Receiver and satellite technologies continued to show gains this past year. The buzz this season has been to purchase units that can access not only the robust U.S. GPS but also Russia's GLONASS system. "All new receivers from the major players are now being manufactured GLONASS-capable and are future-proofing for Galileo (Europe's satellite system)," says Trevor Mecham, Leica's North American business manager, ag. Leica believes in the GLONASS boost so much that any mojoRTK user can demo GLONASS satellite activation before they buy it, to see if it improves their performance along tree lines and during poor satellite availability, says Mecham.
Topcon Positioning System has been working with multiple satellite constellations since 2000, says Mike Gomes, OEM accounts manager. He says the current GLONASS system stands at 16 satellites, with another six slated for launch in 2008. "In a GPS plus GLONASS system, typically users can have between seven and 16 satellites available, even if you go behind a mountain or into a canyon or behind a stand of trees. You can keep going when GPS-only can't," he explains.
Small But Mighty
There's also a move afoot to provide more low cost choices, including units that combine receivers and antennas in one unit, dubbed "smart antennas." Ag Leader introduced its GPS 1500 high-accuracy receiver/antenna late last year. "Our goal was to provide a GPS receiver with the accuracy needed for maximum performance using AutoSwath while keeping it affordable for our customers," says Matt Leinen, GPS and guidance product manager. He says the GPS 1500 offers a fast update rate and sub-meter accuracy.
Hemisphere GPS has the A100 Smart Antenna, calling it an affordable all-in-one DGPS receiver solution that offers fast start-up and reacquisition times and 60-cm accuracy.
The AgGPS 106 is Trimble's all-weather, low cost DGPS smart antenna for yield or field mapping. The company also offers a range of stand-alone receivers (such as the AgGPS 442, 432, and 332) that can be coupled with antenna options to provide a variety of correction and accuracy levels.
There's some debate about which is better: external, stand-alone receivers or receivers built into display boards. Dr. Mike O'Connor, CTO of Novariant-AutoFarm, says customers and dealers prefer a simple connection between the GPS equipment on the roof and the display hardware in the cab. "This generally requires a stand-alone receiver system on the roof of the vehicle, so that a standard wire cable bundle can be run into the cab, rather than a coaxial cable," he describes.
But other manufacturers would disagree. Leica's Mecham believes the only advantage external units have had over the last 10 years is upgradeability. "With the new boards moving to firmware-upgradeable versions, this advantage is basically lost," he says. "Built-in receivers reduce manufacturing costs and reduce field breakdowns due to cable and connector failures."
Multiple antenna set-ups are gaining favor in the industry since they provide very precise positioning as well as heading and terrain compensation measurements, says O'Connor. "This allows vehicles to start automatically steering from a dead stop and to operate at very low speeds."
No matter the guidance set-up, Jim Shone, sales director at TeeJet Technologies, says users don't need to be confused trying to put together pieces-parts like receivers and antenna. The company's entry-level guidance product CenterLine 220 is an answer, and inside the compact lightbar is a high-quality WAAS GPS receiver. "We're trying to make a very simple interface where customers don't have to configure a lot of the settings prior to the operation of our products," he says. "They can just plug and play."
Correction Solutions News
Consumers there are. John Pointon, director of sales and marketing with OmniSTAR, said subscription sales at the company broke all previous records by April 2007 - and broke them again for April 2008.
RTK is also hot. "The biggest advancement in satellites and signals is the proliferation of RTK base stations," says O'Connor. "In many areas it is now possible to purchase a system that is capable of sub-inch RTK steering performance without purchasing and installing your own base station."
One of the leading improvements that John Bohlke, director of product marketing with Hemisphere GPS, sees is with the company's single frequency RTK. In a patented technique, the firm uses SBAS (WAAS, EGNOS, etc.) satellites for ranging in order to improve its RTK solution in the Outback product line. "And just the quality of the Crescent GPS receiver makes it a very affordable way to get centimeter level accuracy," he says. In fact, the Crescent is featured in the new Outback S3, released in 2008.
John Deere Engineer Curtis Hay finds RTK growth — both in network expansion and individual use - is still quite strong, and "StarFire 2 sales are quite good. It points to a growing want and need for centimeter-level accuracy, which would make applications such as strip till or drip tape quite reasonable," he says.