Reconnaissance Scout Signal

A reconnaissance scout signal was a signal sent by a reconnaissance scout. A fleet of Death Squad Daleks would listen for it, and travel to the origin of the signal using the Time Vortex. The Thirteenth Doctor summoned Death Squad Daleks to Earth using this signal in order to rid the Earth of Defence Drones that had gone rogue with impure Kaled mutants inside them. (TV: Revolution of the Daleks)