The Inmarsat-5 IOT system is designed to test the Inmarsat-5 fleet of satellites. The Ka-band test system is built using SED’s standard IOT product as the baseline. In addition to the standard measurements, spread spectrum satellite gain and noise power ratio (NPR) are included as extra measurements. A transportable IOT enclosure and 2.4m antenna are provided to test an extended frequency range beyond the capabilities of the ground station antenna. The first system is installed in Greece, with follow-on systems to be installed in North America and the Pacific ocean region.