明岗暗哨

both covert and undercover (officers) keeping watch (idiom)

Ming Dynasty (1368-1644) / surname Ming / Ming (c. 2000 BC), fourth of the legendary Flame Emperors, 炎帝[Yan2 di4] descended from Shennong 神農|神农[Shen2 nong2] Farmer God

bright / opposite: dark 暗[an4] / (of meaning) clear / to understand / next / public or open / wise / generic term for a sacrifice to the gods

mound / policeman's beat

variant of 岡|冈 [gang1]

(bound form) hillock; mound / sentry post; policeman's beat / (bound form) job; post

variant of 暗[an4]

dark / gloomy / hidden / secret / muddled / obscure / in the dark

to close (a door) / to eclipse / muddled / stupid / ignorant / variant of 暗[an4]

hidden sentry post

a whistle / sentry