Remote switches plate B passively monitoring optical power of the transmit fibers.Since the transceivers are continually transmitting Manchester-coded data or idle tone, this criterion is used in determining whether the switch should activate.When the optical signal is lost on a transmit fiber.It is determined that one of the following failure modes has occurred: either the LED has failed, the transceiver has lost power or been destroyed, or the building to -ring stub has been destroyed, or the building of a ring stub has been destroyed.In this event, the transceiver is automatically bypassed until repairs or replacement can be done.
A complete switch is composed of two identical channels.Each channel services one fiber of the dual counterrotating ring.At the coupling points, ,10 percent of the transmitted optical power are taped off and detected.A PIN photodiode with a low pass preamplifier is utilized to detect the average optical power incident on the detector.The detected power is amplified and compared to a threshold to be transformed into a logic high or low.The resulting digital value is used to place a latching optical switch reduces the abnormal electrical power requirements normally associate with the holding current in the traditional fails safe Mechanical Optical Switch implementations.Additional circuitry gets power to the switch drivers and provides battery backup and recharge.
Prototype o two channel remote bypass switches were constructed.The prototype was placed in a simulated network environment to measure insertion losses, sensitivity, speed of response, and power consumption, In addition, operational test was carried out to examine switching response.Operation ofthe battery backup, and interoperability with the transceivers.
Operational tests showed the switch performed as designed.Switch transitions occurred at the preset threshold levels and within adequate time.Upon the loss of external power, the battery backup was noted to function correctly.
The laboratory prototype of the intelligent Optical Bypass Switch was integrated into the survivable network testbed and produced the expected results.The use of this type of bypass switch in the final implementation can significantly enhance the probability of network survivability.
The laboratory prototype of the intelligent optical bypass switch was integrated into the survivable network testbed and produced the expected results.The use of this type of bypass switch in the ultimate implementation can significantly enhance the probability of network survivability.The MEMS Optical Switch design described above has been tailored for use in this application.However, the concept could be applied to other fiber optic ring architecture.In these applications, the switch would have to rely on the presence of the token or some other keep alive signal to determine the status of its.
