Inmarsat 4 Radio Broadband Global Area Network (BGAN)

HAW I4 antennas

SED provided the design, development, procurement, assembly, test, integration, delivery, installation and test of the BGAN Radio Frequency subsystem. The RF subsystems operate at both C-band and L-band to provide the transmission and reception of communication signals between the ground-based RFS and the Inmarsat 4 satellites. Six sites were provided worldwide to provide both primary and backup operations.

Each system comprises a 16-meter or 13-meter antenna, transmit and receive communication chains, power calibration equipment, reference distribution equipment, monitor and control equipment, PCE and SSR upconverters, L-band uplink equipment and L-band downlink equipment. The 16-meter systems also include capability for TT&C of the Inmarsat 4 satellites. SED custom designed the switching required to implement the complex number of signal paths required, all in redundant configurations. All equipment is controlled and monitored with SED’s MCS that monitors the health and status of all equipment. The system also includes an Uplink Power Control function. It uses a synthesizer to transmit a known carrier to the satellite and then measures the carrier coming back from the satellite and adjusts the HPA attenuation to maintain a constant transmit power level. By transmitting and measuring a known carrier, variations in the transmit chain, such as antenna pointing angle, are calibrated out.

SED continues to provide I4 BGAN Satellite Access Stations (SAS) RFS systems that provide the communications uplink and downlink for national coverage of the Inmarsat 4 BGAN service.