With the next-generation over-the-air (OTA) TV standard, Advanced Television Systems Committee (ATSC) 3.0, TV receiver feedback via broadband or dedicated radio channel will become a standard feature. Real-time TV receiver feedback potentially allows secondary users to access active TV channels without interfering with TV users, which would bring 6–10-fold data rate increase on top of the current TV white-space (TVWS) policy in many metropolitan areas, where a few TVWS channels are available. This demonstration is a proof of concept prototype implementation of a cognitive radio TV (CR-TV) set that allows for dynamic usage of underutilized TV spectrum bands. The demonstration will show the main system capabilities of watching broadcast television, determining unused TV bands in a neighborhood through a spectrum database, and transmitting a custom ATSC signal on the optimal unused channel. Additionally, the system ensures the precedence of licensed users by quickly evacuating channels that are taken by a primary user and finding the next most optimal channel, causing minimal interference. The primary user assisted secondary spectrum access could substantially alleviate the spectrum shortage in areas with the highest wireless traffic volume. In addition, to the best of our knowledge, the demonstration provides the first USRP implementation of an ATSC transmitter, which can benefit the community.