The report "sets the stage for the FCC to move forward," Sharkey said. "This really shows the commission is taking the issue seriously."

Representatives of the NAB and microphone maker Shure weren't immediately available for comment.

For more than two years, large tech companies and consumer groups have been pushing for the FCC to approve use of the spectrum white spaces. Among the companies and groups calling for the FCC to approve white-space devices are Microsoft, Google, Dell, Hewlett-Packard, Public Knowledge, Free Press and the VON Coalition.

FCC approval of the devices would spur innovation and create new jobs in the tech sector, and allow consumers to have a new option for broadband service, supporters say. The TV spectrum would allow broadband signals to travel significantly farther than the spectrum used by WiFi.

But TV stations and wireless-microphone vendors raised concerns about interference even as the FCC conducted tests on prototype devices. The NAB said the FCC tests gave no proof that their signals would be protected from interference. Wireless microphones have long operated in the TV spectrum without FCC licenses, and microphone vendors raised many of the same concerns as TV stations.