Abstract: A data communication system for general purposes having a new ternary carrier frequency shift keying (TCSK) signal. The system is applied to a utility load control by transmission of a sub-carrier of an FM broadcast channel. It is decoded by a receiver, SCA decoder, TCSK filter and a two level or binary converter and used to communicate to a pre-programmed microprocessor which enables various load control functions to be performed. The general system also is given for a QPSK (quadraphase shift keying) operating system.A data transmission filter is split between the transmitter and receiver and is operated in cascade to give individual interference filtering at each end of the transmission while also providing combined action and wave shaping. A high accuracy FM decoder using zero crossing detection enables data recovery with simple circuits. A novel random time load restoration circuit for ramp-up is disclosed. A fail safe relay operator is also disclosed.