Time synchronization for nodes of a broadcast-only network is provided by combining two methods. The first method provides relative synchronization of communication frames of node broadcasts, so that all nodes have frames with aligned start and end times. The second method associates a network time with each frame at each node (i.e., each node locally tracks this network time). When a time-stamped message is received by a node, the node network time is set to the larger of its current value or the time stamp of the received message. Each node increments its network time by the same amount from one communication frame to the next.