Abstract: This invention relates to data transmission system of the type where a plurality of transmitters are located at a location remote from a receiver and are adapted to transmit information from their location in turn to the receiver. The transmitters in the case of this invention are each self-powered and have their own transmitter timer associated with them. They are all set to operate from time zero by a master timer and their individual power sources are recharged for the power dissipated in each of their transmissions by a charging pulse that is received over the transmission line. The resetting of the transmitter timers to cause them to transmit in sequence is done during the recharging period which follows the transmissions of the series of transmitters.