The ground station is the unglamorous half of the satellite transmission, the straight man to the high-flying star. But the systems aren't always in synch, and their flubs can induce headaches as easily as any of their airborne brethren.
Take Globalstar LLP. The company - a partnership among 10 companies, including Loral, Qualcomm, and France Telecom - has plans to open 36 ground stations to relay telephone calls from space through to conventional phone lines back on Earth. Phone service, voice mail, messaging and paging, as well as data services, will be available at a swift 9.6 Kbps.
Three weeks ago, Globalstar began building ground stations in China and Canada. Ground stations serve as gateways that connect the space-borne constellations of satellites with the communications networks and the phones or computers tapping into them. Globalstar's plan seemed simple enough on paper and in pitches to investors, but in reality turned out to be maddeningly complex.
To transmit data over the various phone networks of different countries, Globalstar partnered with phone utilities in key slots around the globe. It soon found there were as many different specifications as languages and hustled to tailor ground stations and tweak switching software algorithms to fit each of the myriad networks.
"When setting up ground stations, each of the Globalstar partners has to take a different approach with each country's infrastructure," said Bob Schmitt, CIO of the US Institute of Peace, a Washington, DC-based organization promoting communications network development in undeveloped countries. "One set of economic models was used in the planning stages and quite another is being found to be the reality. They were warned about that going in."
Globalstar spokesman John Cunningham said the priority was not so much to achieve an advanced satellite technology, but to "provide service around the world at the most affordable rate.... Our system is designed to interface with the local phone switching network on a close basis," he said. "More than 80 percent of calls from a mobile phone go to a fixed phone. So you're going to go into the phone system anyway."
That wasn't all. The government-owned phone companies, which had to sign off on the plan, wanted tariff authority over calls made on the network. So new software algorithms for call-billing have to be added. "It is mostly the software which is the complex side of the system. Each gateway will have its own software suite," Cunningham said. But the cost of the new software - for which Globalstar declined to provide an estimate - is above the planned cost for the project.
Other satellite services are going for simpler approaches. Teledesic's gateways will likely be simple satellite reception dishes hooked to terrestrial phone networks. "There is no need for a user to go through a ground-based gateway. In our system, a gateway is simply an interconnection to the public phone network," said spokesman Roger Nyhus. "We expect them to be widespread and inexpensive."
Over at SkyBridge, plans for ground stations are still on the drawing board since the service won't be in operation before 2002. But SkyBridge attorney Phillip Spector said, "This is a fixed system, not a mobile system. You will have a small dish in your house, not dissimilar to a DirecTV dish, and on that you will be receiving Internet access."
For its part, Globalstar says the problems should be solved by the time the satellites start launching in December. A year later, Globalstar plans to have 48 in orbit. If the ground stations represent the last of Globalstar's glitches, the company will be lucky: they're far easier to fix than a sick satellite in orbit, or one that can't get up there.
And any glitch can cost precious time in a space race.
