Satellite Pass: Doppler Shift & Elevation Tracker

Every low-Earth-orbit satellite pass is a race against the clock and against physics: the satellite is moving several kilometres per second relative to any fixed ground station, so the carrier frequency a receiver locks onto is never quite the one the satellite transmits. This simulator models a real circular LEO orbit — orbital speed from Kepler's third law, slant range and elevation from spherical geometry, and the received downlink frequency from the classical Doppler formula — so you can watch the frequency swing from a positive shift on approach, through zero at closest approach, to a negative shift as the satellite recedes over the horizon. Adjust the orbit altitude, how close the ground track passes overhead, and the downlink band to see how each one reshapes the Doppler curve that real satellite ground stations have to track and compensate for during every single pass.