C1472 Millions of People

"How many 'signal launchers' have we installed?" Lee Zhi, seated atop Lao Huang, inquired with a furrowed brow.

"Thirty-nine, spaced between one thousand and five hundred kilometers apart, each buried at a depth of seven hundred meters. The signal network is intact, with no signs of tampering so far," Xiaobing explained, materializing beside Lee Zhi. A miniature map projected in front of him