Positioning · Navigation · Timing
Understand how the world knows where it is.
From first principles to cutting-edge research — through interactive learning, engineering tools, and real-world applications. Built to cultivate understanding, not just deliver information.
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Concepts
Coordinate Frames
Geodetic, ECEF, and ENU are three different languages for the exact same point. Knowing which one you're speaking — and how to translate — is the quiet backbone of all GNSS.
beginnercoreDilution of Precision
The same measurements can give you a crisp fix or a mushy one depending purely on the geometry of the satellites overhead. DOP is the number that captures that difference.
beginnercorePseudorange
Why the ranges in satellite positioning are politely called "pseudo" — and how one humble, shared clock error turns clean geometry into a four-unknown puzzle.
beginnercoreSatellite Orbits
A GNSS satellite isn't hovering — it's falling, endlessly, and missing the Earth because it's moving sideways fast enough. Kepler's three laws turn that idea into the numbers that decide altitude, period, speed, and where a satellite will be when you need it.
intermediatecoreTrilateration
Finding where you are by measuring how far you are from several known points — the geometric heart of satellite positioning.
beginnercore