Bigger and better than Wi-Fi

THOSE old enough to remember television before the age of cable and satellite TV may have wondered why half the channels on old-style analogue TV sets seemed to be missing. Apart from channel two, the rest of the original VHF channels on the dial were usually just the odd numbers from three to 13. Why? In over-the-air VHF broadcasting, the channel between two analogue stations had to be left unused so that it would not interfere with adjacent ones. When UHF broadcasting came along, empty “guard bands” were added to each channel for the same reason. In some places, this “white space” of unused frequencies separating working channels amounted to as much as 70% of the total bandwidth available for television broadcasting.