Phoenix Logs/UNSC Buildings/Watchtower
From Halopedia, the Halo wiki
The Watchtower is an elevated sensor platform that increase the firebase's line of sight and can detect nearby cloaked units. Additional Watchtowers extends the cloak detection range. Each Watchtower occupies a turret slot.
The multi-modal stealth and jamming systems employed by the Covenant and Banished are a significant strategic challenge for the UNSC. Though improvements have been made, there is still a significant capability gap in detection range versus cloaking capabilities. Nevertheless, with microdrone clouds and hyper scanner technology acquired from former Covenant sources, UNSC firebases can deploy a short-range sensor network that will reliably reveal enemies otherwise shrouded by cloaking generators and active camouflage. Once detected, their location can be shared to all friendly units for targeting.