Similar to Inmarsat-4, SED’s systems plays an integral part in the real-time management of the Inmarsat-3 satellite resources. Centralized Network Coordination Stations (NCS), designed and built by SED, coordinate the usage of shared satellite resources amongst multiple geographically-separated ground gateways. The gateways, using out-of-band satellite control channels, communicate with the NCS to acquire demand assigned shared channels for short-to-medium duration SCPC-based services such as voice, fax, and ISDN.
Rather than dividing the limited spectrum between gateways that may have varying diurnal traffic profiles, the NCS offers a sophisticated planning mechanism that allows spectrum to be shared by different services having different waveforms, bandwidths, and power requirements. Services can be prioritized and the NCS supports preemption to accommodate critical services, such as safety and emergency. Additionally, occasional, off-peak, and long-term spectrum leases are accommodated using autonomous scheduling mechanisms and, in some cases, dedicated systems.
Originally installed in 1998, SED has successfully supported and evolved the NCS for almost 15 years, including 6 global locations and multiple relocations. Through SED’s commitment to retain system knowledge and continual software and hardware improvement, Inmarsat has enjoyed commercial success of the Inmarsat-3 network for a satellite lifetime and more.