The subject is pretty clear , But how it works? TV signals use different parts of the radio spectrum to radar, but both bounce off solid objects. Using special receivers, researchers said they were able to track up to 30 planes simultaneously flying at altitudes of up to 10,000ft (3km).
The study involved a TV signal broadcast by a transmitter at Crystal Palace in London.
Three specialist receivers were used to measure the directions of the signals that reflected off the aircraft and the differences in time they took to be received compared to the rest of the unimpeded TV signal.
This “triangulated” information was then used to deduce the various planes’ locations.
Seems that it’s worth,because Using TV signals instead could save money and free up valuable radio spectrum for other uses,
A follow-up trial in Liverpool suggested that the TV signal-based system experienced less interference from wind turbines than traditional radar receivers.