Before revision: Satellite navigation systems offer better accuracy than any land-based system, are available at almost all locations on the Earth, can be implemented (receiver-side) a modest cost and complexity, with modern electronics, and require only a few dozen satellites to provide worldwide coverage.
After revision: Sattellite navigation systems offer better accuracy than any land-based system, are available at almost all locations on the Earth, can be implemented (receiver-side) a modest cost and complexity, with modern electronics, and require only a few dozen satellites to provide worldwide coverage.