ASFOM Redundant Point-to-Point or Bus Transmission Systems
The ASFOM range can be configured to provide backup links for both point-to-point and bus systems. Redundancy is created by offering two independent paths for the optical signal – the primary and the secondary path. Under normal operation, the primary path is used; in the event of a failure, the receive end of the link takes the lost information from the secondary path. To further increase the resilience to failure, the unique KBC solution splits the electrical signal before transmitting it through dual identical transmit and receive optics. This means that an optical component failure will not cause a system failure. In a system that uses optical splitting, an optical failure in the transmitter or receiver will result in a system failure as there is only one set of optics. Electrical splitting also removes the need for passive optical splitters / couplers at each remote position and an optical switch at the receiver end, removing single points of failure and increasing the usable optical budget in the system. Alarm outputs, corresponding to every used optical wavelength are provided at the head end / central location unit. When an optical path is lost, be that optical component failure or loss of link continuity, the alarm output changes state to indicate the failure. By monitoring both the primary and secondary paths, failures in links that are not currently being used are still identified and can be rectified quickly. Depending on system requirements, units are available in 1U or 2U 19” rack or 4U chassis card for integration within the FR4 chassis.
Typical System Configuration:
- Video, audio, data, telephone, contact closure & Ethernet interfaces
- Application specific product configuration
- Redundant links provide back up in case of failure
- Alarm outputs for all used optical wavelengths
- Unique electrical splitting
- All digital non-compressed
- Rack or chassis configurations
Contact Closure Alarm Output
Response Time: 500μs
Output: SPST Relay, Normally Open
Switch Rating: 1A @ 30 Vdc max, 0.5A @ 125 Vac max
In the event of a failure in the primary path at optical wavelength λx, the control line to the switch (OSLDO) changes state and the corresponding electrical data at optical wavelength λx is taken from the secondary path. The switch control line keeps the switch in the secondary path position until the failure in the primary path is rectified. Once the fault is rectified data is immediately taken from the primary path. Only data passing on wavelength λx is taken from the secondary path, all other wavelengths in the primary path are used for data transfer. The OSLDO line will also change the state of the contact closure alarm output to notify the user that a fault has occurred. If an optical wavelength in the secondary path is lost, the OSLDO line changes the state of the contact closure alarm output to notify the system user that there is a potential issue if the secondary path is ever required.