signal towers
Elevated transmission structures
Signal towers are elevated structures built to transmit messages across distances, historically using fire, smoke, flags, or semaphore systems.
Ancient and medieval civilizations constructed chains of signal towers along borders or coastlines, allowing warnings to travel faster than messengers: Signal towers along the Great Wall alerted garrisons to approaching enemies.
The term sometimes applies to modern railway or traffic control towers.
- semaphoreFlag-based signaling system
- lighthouseCoastal beacon tower
- warning beaconFlashing light signaling danger
- watchtowerElevated structure for surveillance
- heliographSunlight-based signaling device
wigwag · beacon · torch light · smoke signals · pigeon loft · base stations · relay station · communication network · signalmen · communication · satellite dish · navigation aids · flagpole · telegraph pole · antennas · line of sight · lookout · early warning
signal towersreceivers
Those who accept transmissions
satellite dishes · radio receivers · listening posts · ground stations
signal towersdead zones
Areas lacking life or signal
signal jammers · radio silence · Faraday cages · blind spots
signal towersunderground bunkers
Fortified subterranean refuges