"China Lake is the United States Navy's largest single landholding, representing 85 percent of the Navy’s land for weapons and armaments research, development, acquisition, testing and evaluation (RDAT&E) use and 38 percent of the Navy’s land holdings worldwide. In total, its two ranges and main site cover more than 1,100,000 acres (4,500 km2), an area larger than the state of Rhode Island."

Possibly to ensure that weapons and weapon systems that use GPS will still function in it's absence.

It's classified, but they may have been testing GPS jamming equipment or other rf tech that has that as a side effect.