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by oh_sigh 2278 days ago
Even relying on GPS is overdoing it. Paint a white stripe on a tire using a permanent marker, and then mount an IR emitter and phototransistor in the wheel well. Knowing the diameter of the tire and the time between revolutions lets you easily figure out speed.
1 comments

Great idea! But I think this is harder than GPS because the chip simply spits out speed and direction.