When that winter Tuesday arrives, just 16 days after the Super Bowl and 28 days after the next presidential inauguration, each full-power TV station in the land will need to turn off its traditional analog signal and send all programs over the air as digits. Analog TV sets can’t translate digital signals. Without the proper equipment to convert those digits back into wave-like analog signals, 73 million analog TVs dispersed among 109 million U.S. TV households, including cable and satellite TV homes, are expected to go dark. If millions of consumers find they suddenly can’t watch TV because of this...