The British Royal Air Force says a bad digital television receiver set off a helicopter rescue mission after sending out a rogue distress signal.

The "freeview" box, which normally gives viewers access to dozens of digital TV and radio channels through a standard, rooftop signal, sent out signal identical to that of an emergency beacon out at sea.

The signal, which emitted from Portsmouth, was picked up by a satellite and beamed to the RAF's Aeronautical Rescue Co-ordination Center in Kinloss, northeast Scotland.

Workers there notified English coastguards, who sent a helicopter to investigate. The helicopter spent two hours flying over Portsmouth Harbor looking for distressed sailors.

The signal was eventually traced to dry land.