Abstract: Apparatus for multiplexing ancillary devices in a streamer cable towed by a boat in ocean seismic operation, in which the cable includes a plurality of ancillary devices located throughout the cable. The apparatus includes a source providing step pulses located on the boat. Also located on the boat is a circuit providing control signals and a network providing control voltages. A plurality of series connected control pulse circuits are located in the streamer cable with the first control pulse circuit of the series being connected to the step pulse source. The control pulse circuits are responsive to the step pulses for providing a plurality of control pulses in a predetermined sequence. An energizing voltage source located on the boat provides a square wave energizing voltage. A plurality of switching networks are located throughout the cable with each switching network being connected to a corresponding ancillary device.