FARNBOROUGH, England — Mobile satellite services provider Inmarsat on July 14 said it had successfully tested high-throughput links between its first Global Xpress Ka-band satellite and terminals on the ground in Bath, England, which is located at the extreme northwest limit of the satellite’s coverage area.

The satellite, called Inmarsat 5 F1, was launched in December as the first of three or four Global Xpress satellites to provide global coverage to commercial and military customers. For military users, the fleet will complement the U.S. Air Force’s Wideband Global Satcom constellation of satellites, which like Global Xpress operates from geostationary orbit.

The next two Global Xpress satellites — a fourth satellite was ordered more recently from prime contractor Boeing Space and Intelligence Systems of El Segundo, California, and will be launched at a later date — are awaiting clarification of the Russian Proton rocket’s schedule as that vehicle prepares to return to flight following a May failure.

Industry officials said London-based Inmarsat is likely to get one of its two planned Proton Global Xpress launches off this year, with the other to be pushed into 2015.

Each satellite carries 89 spot beams, of which 72 may be in use at any one time, plus a six-beam High-Capacity Overlay that can toggle between military and commercial Ka-band frequencies.

From its position at 62.6 degrees east longitude over the Indian Ocean, Inmarsat 5 F1 covers about one-third of the globe except for the North and South poles.

Bath is located at 51.4 degrees north latitude and 2.36 degrees west latitude — at the limits of its reach.

In a presentation here during the Farnborough Air Show, Andy Start, president of Inmarsat’s Global Government division, said the test at Bath, at a facility operated by Inmarsat value-added reseller Airbus Defence and Space, demonstrated sustained links at 10 megabits per second using 75-centimeter-diameter terminals.

The terminals were designed for aeronautical use but in this case were on the ground, aimed to pick up the signal at an exceptionally low-elevation look angle.

Inmarsat has said that its terminals cost about one-third the price of military-specified equipment.

Inmarsat made its presentation alongside Telespazio, a large satellite services company that is majority owned by Italy’s Finmeccanica, with a minority share held by Thales Group of France.

Like Airbus, Telespazio is a value-added reseller of Global Xpress services for government and enterprise customers in Europe, the Middle East, Africa and Latin America.

Pointing to the static display outside the Finmeccanica auditorium, Start said the range of Finmeccanica airborne platforms and Finmeccanica’s global customer base for civil and military aircraft are one reason  Inmarsat wanted Telespazio on board as a Global Xpress reseller.

The U.S. Air Force has ordered 10 WGS satellites, including two that have been financed by U.S. allies Australia, Canada, Denmark, Luxembourg, the Netherlands and New Zealand.

Start said the number of WGS satellites — as many as 10 in orbit, or as few as eight depending on how the U.S. Air Force’s operating scenario evolves — will have no material effect on Global Xpress’s markets.

“We have always said this should be viewed as complementary,” Start said. “We can offer WGS users in-fill and roaming capability for when they move out of WGS coverage. The business case for us does not really change” with the number of WGS satellites placed into service.

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Peter B. de Selding was the Paris Bureau Chief for SpaceNews.