Patent ID: 6650839
Filing Date: 2003-11-18
Classification: H04B

Abstract:
In an optical communications system having plural remote terminals coupled to a central terminal over a shared optical transmission medium, the plural remote terminals configured to transmit data on the shared optical transmission medium at prescribed transmission time intervals and in a prescribed sequence, remote terminal apparatus comprising:an optical transmitter for transmitting data onto the shared optical transmission medium; a fault monitoring circuit coupled to the optical transmitter for monitoring activity of the optical transmitter and providing a first fault indication signal upon optical transmitter activity occurring for a duration that exceeds a fault time interval; and a deactivation circuit responsive to the first fault indication signal to deactivate the optical transmitter; further comprising a transmitter controller providing a transmit enable signal for enabling the optical transmitter wherein under normal operation of the remote terminal the transmit enable signal is asserted during the prescribed transmission time interval and wherein the optical transmitter includes an optical detector for detecting the presence of optical transmitter energy into the shared medium to provide an activity signal to the fault monitoring circuit which operates to provide the first fault indication signal upon the transmit enable signal being unasserted and the activity signal being present for a duration that exceeds the fault time interval.