15 Why GNSS Can No Longer Be Treated as a Given In controlled test environments, GNSS often performs flawlessly. But the real world is far less forgiving. You may think that what you have in your car is a GNSS... well, not really. Your car’s navigation system uses a GNSS receiver—usually GPS, sometimes GPS + GLONASS or GPS + Galileo — to calculate its position. It means that your car is not a GNSS system, but it is a device that receives GNSS signals. Think of it like this: GNSS = the radio towers in the sky. Your car = the radio that listens to them. For your farm vehicle, GNSS is different. A farm vehicle uses GNSS very differently than a car— it’s more precise, more complex, and far more dependent on reliability. Your car just needs to know roughly where it is on a road, so GPS provides it with an accuracy of being within 10 to 33 feet. Your tractor or sprayer, however, needs to know where it is within a few centimeters, even when GNSS signals degrade, because it needs to control autosteer, section control, variable‑rate application, and planting and strip‑till alignment. A modern farm vehicle using RTK‑corrected GNSS can steer with repeatable accuracy of about half an inch, far tighter than the typical GPS in your car. And yet, Gallup noted a problem. She explained that “urban canyons create multipath errors. Tunnels block signals. RF jamming disrupts reception, and spoofing attacks can inject false position data.” Agriculture faces its own challenges: tree lines, grain bins, metal structures, and terrain features can all degrade satellite reception. And as more rural broadband and wireless infrastructure is deployed, the risk of unintentional interference grows. For autonomous systems, the consequences of all of this are serious. A navigation stack that depends too heavily on GNSS can drift, jump, or collapse entirely when signals degrade. Gallup said the difference between a system that degrades gracefully and one that fails outright “is the quality of your inertial backbone.” Inertial Sensing Becomes the Primary Reference Modern navigation architectures are shifting away from GNSS‑centric designs and toward inertial‑first systems. As Gallup explained, “A well-designed inertial navigation system like the 3DM-CV7-INS gives you continuous motion propagation built on careful thermal calibration and a synchronised multi-IMU (inertial measurement unit) architecture. It doesn’t depend on satellites. It depends on physics.” IMUs track acceleration and rotation, allowing the navigation system to estimate motion even without any external signals. High‑quality calibration and noise reduction slow the natural drift that accumulates during dead reckoning. That stability gives the system time to survive GNSS outages without losing track of its position. External sensors then act as “aiding inputs” that As GNSS reliability erodes in real‑world conditions, engineers are turning to inertial sensing and sensor fusion to keep autonomous systems on track. PHOTO: Sutad Watthanakul/iStock/Getty Images Plus
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