https://www.theregister.co.uk/2018/02/20/vodafone_4g_drone_tracking_idea/ >Vodafone is working on an airborne drone detection system based on 4G M2M mobile phone technology, the network operator said this morning. >The “pioneering technology”, as Voda has dubbed it, works by putting a standard 4G SIM card and radio onto a drone. The mobile operator then tracks the drone through a method that it calls a Radio Positioning System (RPS, capital letters and all).