This read-write object selects the transmit clock source: internal(0), Tx Terrestrial(1), or Loop-Timed(2). This determines what governs the timing of data leaving the modem toward the satellite -- internal uses the modem's own clock, Tx Terrestrial derives timing from the incoming data interface, and Loop-Timed derives it from the recovered receive clock, and choosing the wrong source for a given network topology, such as loop timing two ends against each other, can create a timing reference conflict leading to buffer slips. In a network where a hub station provides the master timing reference, a remote CDM-570 would typically be set to loopTimed(2) so its transmit timing tracks the hub's recovered receive clock rather than running on its own independent internal clock.