distress signal
From Trekipedia
Old-style distress signals—such as those in use aboard the S.S. Columbia when it disappeared in 2236—were designed to interfere with systems and attract the attention of a ship's crew. When the U.S.S. Enterprise NCC-1701 intercepted an old-style signal in 2254, collision warnings and the red alert klaxon were activated in response.[1]
