At the distances involved, I'd stick with the rope. Involving orbiting atomic clocks entail a number of sources of error[1] that add up to about 15 meters. It'

At the distances involved, I'd stick with the rope. Involving orbiting atomic clocks entail a number of sources of error[1] that add up to about 15 meters. It's possible that an electronic based system could be built, but it would require two transceivers that can measure phase differences of nanoseconds between transmitted and received signals. I'm not aware of any cheap off the shelf systems like that. [1] https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_...