Someone is spoofing GPS signals in Shanghai, and we’re not entirely sure why they’re doing it, or how. One ostensibly bizarre theory: sand thieves trying to obfuscate illegal dredging by zonking out the GPS received by other ships’ AIS transponders. But how they’re redesignating ship (and bicycle) GPS locations into riverside circles, rather than, say, shifting everyone’s position a few kilometres away, has not yet been figured out. [MetaFilter]

Previously: The Russians Are Spoofing! The Russians Are Spoofing!