SATELLITE SYSTEMS AND TECHNOLOGY

A background summary on communications wouldn’t be complete without including satellite systems and technology, another unique segment of the field. The global satellite system today has evolved over more than 40 years. Satellite services are grouped into fixed satellite service (FSS) and broadcast satellite service (BSS) by the ITU. The more common informal reference for the BSS is DBS, meaning direct broadcast service. In addition to communications, satellite systems and technology provide vital weather information, mapping, location information through the global positioning system, plus many valuable services to the military.

The current DBS system is conceptually very similar to one ArthurC. Clarke described in an article written in the fall of 1945 for Wireless World. In this article, he foresaw 24-hour manned satellites being used to distribute television programs. Despite a repeated version of the concept in another publication, The Exploration of Space written in the early 1950s, the idea never gained much interest or attention.

John Pierce of AT&T Bell Labs is credited with being the first to take serious technical and financial interest in the idea. Pierce elaborated on the basic idea to the extent that the space-based platforms would perform much like a mirror and be located in medium and 24-hour orbits. He estimated the capacity of the satellite to be equivalent to 1000 simultaneous telephone calls and comparing it to the first trans-Atlantic telephone cable with a capacity of 36 simultaneous calls, arrived at a conclusion that it would cost 36 million dollars and be worth a billion.

AT&T caught the FCC by surprise in 1960 when it requested permission to launch an experimental satellite. At the time, the commission and other parts of the government simply weren’t equipped with policy and rules covering satellite communications. RCA was awarded a contract to build a medium-orbit satellite in mid-1961. Around the same time, Hughes was awarded a contract to build a high orbit, 24-hour satellite. By 1964, four medium-orbit and two high-orbit satellites had operated successfully. The Communications Satellite Act of 1962 formed the basis for Communications Satellite Corporation with an initial capitalization of 200 million dollars to build a system of several dozen medium-orbit satellites. Ultimately, COMSAT decided to build satellites for the higher geosynchronous orbit, the first of which was launched from Cape Canaveral in April 1965.

A key early broadcast event was televising part of the 1964 Tokyo Olympics. At the same time the United States was gaining this initial expertise and capability, other countries had been involved from the beginning. American companies built COMSAT’s initial satellites and launch vehicles. AT&T negotiated with Foreign PTT organizations to build earth stations and began tests and experiments aimed at providing telephone service. By the time COMSAT’s first satellite was launched and ready for service, France, the United Kingdom, Germany, Italy, Brazil, and Japan had operational earth stations. In August 1964, agreements were signed to create the International Telecommunications Satellite Organization (Intelsat).

By 1969, when Apollo 11 landed on the moon, half a billion people watched the event all over the globe through Intelsat transmission facilities. The last facilities making up the first global network were placed in service over the Indian Ocean just days before the moon landing occurred on July 20, 1969.

ABC proposed a domestic satellite system to distribute television signals in 1965, but it never gained traction. In 1972, ANIK was placed in service by Telesat Canada to serve the vast regions of the country. RCA and Western Union both launched the first domestic satellites in 1974 and 1975. AT&T launched its first domestic satellite in 1976. Satellites were intended to provide voice and data service; however, television quickly became a major user. By the end of 1976, 120 transponders were in service, each capable of 1500 telephone conversations or one TV program. Movie channels and super stations were made available to cable head ends, driving the growth in cable TV demand. During this same period, the major radio and television networks began using satellites to distribute programming to their affiliates. Satellite distribution would prove far more reliable and less expensive than terrestrial networks.

Arthur Clark’s vision of watching television from a satellite would be realized in the fall of 1994 when Hughes, RCA, and Hubbard Broadcasting launched the DirecTV transmission system. The first serious competition for cable got off the ground. A few years later, Echostar would launch its Dish Network.

A key component of satellite technology, the traveling-wave tube (TWT) was invented in England and perfected at Bell Labs. It is used to generate the signal transmitted from the ground to the satellite and back from the satellite-to-ground station receivers. Achieving adequate power level for the signal to be received by the satellite and re-transmitted back to earth required very large (100-foot diameter) dish antennas in the early uplink transmission systems. Early TWT power output levels were only approximately 1 W, but they have grown to more than 300 W. Uplink antennas approaching one tenth the size of early versions now cost around 30,000. Receiving antennas that are the size of a large pizza now enable reception of several hundred TV programs and data links to millions of businesses requiring credit card authorizations and accurate inventory tracking.

When COMSAT launched its first satellite in 1965, it provided almost 10 times the capacity of the submarine telephone cables for almost one tenth the price. Telephone service on a satellite facility suffers from the long path it must travel. In the early days, the availability of the service was its key selling point. Satellite telephone service is still the service to and between many countries today. The first fiber cable, TAT-8, was laid in the Atlantic Ocean in the mid-1980s and provided competition. Satellites are still competitive in many applications, especially point-to-multipoint service such as DBS and network distribution to affiliates.