How is (non-interfering) data communication possible over the tv spectrum? What is the technology used?
After some research, i found that the wireless data communication over TV spectrum is made possible through the IEEE 802.22 (Super-Wifi) technology which is a Wireless Regional Area Network (WRAN) standard. It uses the white space available in the TV frequency spectrum. The interference with TV channels are prevented by means of Cognitive Radio (CR) technique as well as other spectrum sensing and allocation methodologies. IEEE 802.22 uses VHF/UHF TV broadcast bands between 54 MHz to 862 MHz.

The standard is currently proposed for unlicensed public use. The theoretical range of this network is upto 100km with wired broadband compatible speed (1.5Mbps).