Complex sentence: A SIGINT Activity Designator (or SIGAD) identifies a signals intelligence (SIGINT) line of collection activity associated with a signals collection station, such as a base or a ship.
Split into simpler sentences: A SIGINT Activity Designator (or SIGAD) designates a Signals Intelligence (SIGINT) line of collection activity. These are associated with a signals collection stations, which may be a base or a ship.