‘Lighthouses in space’: the Chinese jam-proof satellite network to fill GPS gaps

Chinese researchers say they have built an 11-satellite network for a jam-resistant, high-accuracy optical navigation system, designed to provide positioning where GPS is unavailable or disrupted, from self-driving cars and drones to deep-space missions.

Optical navigation has also been used in the ongoing US-Israeli war with Iran, helping drones developed by companies such as Asio Technologies and General Atomics operate in environments where GPS signals are jammed.

While positioning systems such as GPS and BeiDou rely on satellites that beam radio waves, Tsinghua University’s new network uses coded light signals from “beacon” satellites.

Xing Fei, a professor of precision instrumentation at Tsinghua University who led the project, told Beijing Youth Daily on Tuesday that ancient sailors navigated by lighthouses. “What we’ve done is put those ‘lighthouses’ in space, using light-emitting satellites to guide everything from vehicles to spacecraft.”

The system works by placing powerful light sources on satellites to send coded signals to Earth. Receivers on the ground detect the light and use its direction, along with the satellites’ known positions, to calculate where they are.

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Because light beams are narrow and travel in straight lines, they are much harder to interfere with than radio signals, according to Xing. Compared with star-based navigation, which relies on faint, fixed stars and offers limited accuracy, it can deliver much more precise positioning.

South China Morning Post