Complementary Relationship Between 2 Communications Technologies : Optical Fiber Systems Ease Load on Satellites
Sometime in November, assuming nothing major goes wrong, the first commercial transmissions will flow along a newly laid cable that snakes 3,600 miles across the floor of the Atlantic, linking Europe and North America.
Though only three-quarters of an inch in diameter, it will have room to carry as many as 40,000 phone calls at once, four times what the Atlantic’s most advanced and much bulkier copper cable can handle. The new one also can carry computer data and video images.
The cable will mark the debut of a hot new communications medium--optical fiber--in the most densely traveled path in international communications. But what will happen if nibbling sharks, which for some reason are attracted to the cable, or errant computers cause this marvel of technology to shut down?
The traffic will be diverted to satellites, a technology more than two decades old.
In the 1980s, optical fiber has received a hero’s welcome from politicians, the media and parts of the telecommunications industry. Satellites have been put on the defensive, depicted as in their twilight, destined to fall into disuse as the entire world is wired in fiber.
In fact, the two means of long-distance transmission are slowly working out a complementary relationship. Each can do things the other can’t.
The role of satellites is changing markedly as more and more fiber is laid (the Rhode Island research firm KMI Corp. estimates that about 625,000 miles of fiber strands will be installed this year).
But satellites’ importance and the prosperity of the industry that builds and operates them is assured for the foreseeable future.
Adds to Uncertainty
In many of today’s complex communications systems, “our experience has been that you want to use both media in order to come up with an optimum solution for a particular customer,” said John Berndt, a senior vice president at American Telephone & Telegraph Co., the U.S. member of an international consortium that is building the Atlantic cable.
Still, no one knows quite what form this symbiosis will take in the fast-evolving world network. That adds to the uncertainty facing companies and government agencies that in coming years will have to bet billions of dollars on one technology or the other.
Science-fiction writer Arthur C. Clarke is commonly credited with conceiving the idea of global communications satellites, in a 1945 magazine article. It wasn’t until 1965, however, that the newly formed Intelsat consortium launched the first for commercial use.
Satellites quickly became the favored means to transmit international calls, data and television material. Later, satellites came to play a role in domestic long-distance communications as well.
It was in 1977 that fiber began to emerge as something more than an interesting laboratory phenomenon. That year, fiber-based phone systems were tested in Chicago and Long Beach.
They provided an all-new method of transmission, using the “digital” approach of representing information as streams of ones and zeros rather than variations in electrical waves, as conventional “analog” systems do.
Optical-fiber systems transformed phone conversations into tiny pulses of light and sent them along light-conducting cables at rates of billions per second. Reassembled at the other end, the pulses produced quality that was markedly above anything that analog systems could manage. Their capacity also was much higher than analog cables--potentially 30,000 phone conversations down a single cable the size of a human hair.
Superior Technology
Fiber people talk of it with almost evangelical fervor.
“Fiber is one of those technologies that simply offers something for everyone,” said David Charlton, a market development manager at Corning Glass Works, pioneer and the country’s premier optical fiber manufacturer. “There’s almost no dimension in which fiber doesn’t beat alternative technology.”
David Gergacz, chief operating officer for network systems at US Sprint Communications Co., the country’s third-largest long-distance carrier, voiced similar enthusiasm. “We are thoroughly convinced that fiber is the way to go,” he said. “There is nothing else on the marketplace today that provides the clarity and the overall quality.”
By the early 1980s, costs had dropped enough that large-scale investments in the technology could begin. US Sprint began building a $3-billion, 23,000-mile, all-fiber network. It spent millions of dollars more on ads boasting that its lines were so clear that transcontinental callers literally could hear a pin drop.
AT&T; and MCI Communications Corp., the No. 2 long-distance carrier, began extensive programs to lay fiber and retire analog equipment as well their network of microwave transmission towers, another main method of long-distance communication. Many smaller regional companies made a move toward fiber, too.
Fiber’s fortunes were also boosted by the chaos that gripped the U.S. satellite-launching program after the loss of the space shuttle Challenger in 1986, many analysts say.
It was only a matter of time before fiber went transoceanic. AT&T;’s consortium sank $360 million into the new Atlantic cable, which is supposed to last 25 years (it has been buried four feet under the ocean floor on the continental shelves at either end, to reduce the danger of trawling lines ripping it up). Plans now are proceeding for the laying of a second, higher-capacity cable, to enter service in 1991. The Pacific is to get a cable too.
Echoes Are a Problem
Fiber’s biggest impact on satellites has been to take voice traffic away from them on the big high-density routes. “Fiber optics lends itself to carry very heavy traffic loads over great distances very economically,” said Victor Krueger, a vice president at the California research firm Dataquest Inc.
It is also commonly said to be more satisfying to the caller: Words in a conversation traveling by satellite are delayed by about a half second as the signal bounces 23,000 miles up into space and 23,000 miles back. (Satellite partisans, however, argue that with advances in echo-suppression and other improvements, the average person isn’t aware of the phenomenon.)
Satellite operators have fought hard to retain the traffic, arguing in sales meetings and technical papers that cost and technical merits of fiber are overrated. Some suggest that fiber’s inroads grow in part from its champions’ political clout.
“Despite all the partisan clamor, satellites generally have a clear economic advantage, at least for the long-distance transoceanic routes,” Bruno Miglio, a scientist at satellite maker Hughes Aircraft Co., wrote recently.
They also claim their systems are more reliable. Communications Satellite Corp. (Comsat), the Washington company that channels U.S. traffic into Intelsat, says it derives 5% to 6% of its international revenue by “restoring” disruptions in oceanic cable service. From March 27 to April 13 last year, for instance, it carried traffic diverted from a 3,100-circuit AT&T; cable that was out of service.
Once in orbit, they argue, satellites have virtual 100% reliability, while cables are vulnerable to “backhoe fade,” the disruption caused when a construction crew severs a cable.
Digital Technology
A recent telephone-exchange fire that knocked out service in a large section of Chicago spurred new interest in independent satellite systems, noted Bill Perigard, president of Contel ASC, a Rockville, Md.-based provider of communications networks.
The satellite industry at the same time has worked hard to upgrade its equipment to match fiber’s allure. It is introducing digital technology. It is boosting its satellites’ power, meaning that ground stations can be smaller and cheaper, and redesigning them with versatility in mind.
Armed with changes like these, said Susan Mayer, Comsat’s vice president of corporate development, “satellites will remain competitive with fiber optics over the longer term, not just the next five years.”
Satellite operators have often found the long-distance companies happy to help keep them in business, however, in order to make their networks more redundant and reliable. Comsat last year signed an agreement with AT&T; by which Comsat is guaranteed about a third of all new AT&T; overseas traffic through 1994.
Satellites will also remain important in phone traffic to small countries where economics do not justify a cable.
Nonetheless, the satellite industry recognizes that it is going to have to change, and in a big way. “We’re seeing the applications shift back to where the satellite really has its strength,” said Rex Hollis, a business development director at satellite manufacturer Ford Aerospace Corp.
Satellites’ Advantage
A satellite typically costs hundreds of millions of dollars to build and launch, but once it enters orbit it can link any point on the globe below with any other point. All that is necessary is to put a dish at those two spots. Or more than one point can receive a single signal, a capability that contrasts with a fiber cable’s inherent limitation of linking only two spots.
Those attributes have helped satellites remain the favored medium for distributing television programming. A signal going up to a satellite from a New York distribution center, for instance, can be received by hundreds of stations. ABC and CBS recently made public long-term commitments to satellite distribution.
But some analysts foresee defections among broadcasters. Serious experiments are under way toward fiber distribution networks. “Fiber will be used more and more in the broadcast industry,” predicted Gerald F. Clement, assistant vice president of marketing for Lightnet, a Rockville, Md., company that operates a fiber network. “But it’s going to take some time.”
Satellite companies also are hoping for rapid expansion of private data networks. Dishes on Holiday Inn roofs receive reservation information from headquarters; dishes at 7-Eleven convenience stores send in sales reports. Dataquest estimates that spending for hardware and services for this business totaled only about $92 million in 1987, but it expects the total to hit $490 million by 1992. (Rapid expansion has been predicted before, however, and not come to pass.)
Plans Under Way
Satellites also are expected to play an increasing role in “mobile” communications. U.S. paging companies are beginning to use them to track people down nationally rather than in just one city.
Two companies, meanwhile, are introducing the first satellite-based data link services between trucks and headquarters dispatchers. Others are laying plans for satellite networks that would resemble today’s cellular telephone systems but would cover the entire country.
With all of this happening, the satellite industry remains optimistic, said Michael Feazel, managing editor of the trade journal Satellite Week. The Federal Communications Commission is now examining applications from six companies to launch 15 satellites for the U.S. domestic market.
“Fifteen satellites amounts to probably $2 billion,” Feazel said. “They’re not going to make that kind of investment unless they think there is a future for satellites.”
