A distributed artificial intelligence data acquisition and equipment control system forms a local area network (LAN) over the AC power lines of a vessel for communicating shipboard engineering casualty and damage control information. Each node in the LAN includes a power line carrier current (PLCC) transceiver, a slave processing unit for interfacing with local sensors or equipment and a master processing unit for controlling the formation, transmission and reception of offset-quadrature-phase-shift-keyed (OQPSK) LAN messages. Nodes in the LAN are strategically positioned at various locations throughout the ship and are configured to function either as a Terminal Unit or as a Data & Control Unit. Terminal Units are equipped with a touch screen display and an intelligent controller that provides a user-friendly interactive operator interface through a series of display screen prompts and includes a data base of ship casualty and damage control information stored in a local non-volatile random access memory. The data base, containing both archived and current data, is maintained and constantly updated by each terminal unit in response to information acquired both locally and from other nodes in the LAN. Each Terminal Unit is assigned specific damage control responsibilities for monitoring conditions, controlling equipment and for exchanging data and commands with other nodes. Data and Control units perform monitoring and control functions similar to Terminal Units, but have no touch screen and provide no user interface. The PLCC transceiver at each node includes an improved low noise transmitter that employs a direct digital modulation (DDM) technique utilizing ROM stored waveforms and an improved receiver that uses a passive linear-phase bandpass detection filter and a switchable phase-locked/Costas loop for highly reliable, rapid acquisition of PSK signals.