An automated distress signal was a generated distress call calling for assistance.
In August 2151, Starfleet Command picked up an automated distress signal from the Earth Cargo Service freighter ECS Fortunate and ordered Enterprise NX-01 to investigate as the Fortunate was not responding to their hails.
When first officer Matthew Ryan later told the away team from Enterprise they needed no assistance, he was asked why they sent out a distress call. He told that a younger crewman panicked and hit the emergency beacon. (ENT: "Fortunate Son")