The proposed system works by utilising the TV transmitters that are dotted around the UK.
Each will receive the same TV signal but at a slightly different time because of the reflections and interactions with aircraft flying in their vicinity.
The received signals are then compared to the original broadcast, and the difference is used to locate the position of the aircraft.
Could some knowledgeable person elaborate - one of the basic principles is apparent but the Beeb "technology reporter" is a bit sparse with the detail!
2 s