The use of redundancy and control facilities in satellite modem clusters

Backup or redundancy systems are used wherever the integrity of a link is to be maintained in the event of equipment failure. Redundancy may take the form of simple 1:1 configurations through to the more complex M:N configurations. The use of a separate switching unit allows each individual modem to be removed for servicing without having to disconnect and then reconnect the circuit as would be the case if switching were internal to each modem. When used in a redundancy cluster it is essential that the redundancy switch is the RS485 controller. All the individual modems and framing units within the cluster become slaves. Should external monitoring or control be required a secondary port may be included on the switch for this remote function