VOA Fact Sheet
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Office of Engineering and Technical Services The Magic "A fraction of a second after broadcasters begin their programs, their words reach listeners thousands of miles away from the microphone." Thanks to the Office of Engineering and Technical Services, part of the International Broadcasting Bureau (IBB), the voices of the broadcasters travel from studio to orbiting satellite and are returned to Earth for transmission on a broadcast band, and, in growing numbers, are directed to home satellite receivers. The IBB’s digital satellite system and other leased circuits feed programs to transmission sites in Africa, Asia, Central America, Europe, the Middle East, and the United States. IBB's Office of Engineering delivers the radio and television programs of Radio Free Asia (RFA), Radio Free Europe/Radio Liberty (RFE/RL), Radio and TV Marti, Voice of America (VOA), WORLDNET Television, and VOA-TV. Engineering also transmits the television signals of the Department of State to U.S. embassies worldwide on the new American Embassy Television Network. Staffs around the globe plan, construct, operate, and maintain signal delivery systems or contract for appropriate technical services. In Washington, D.C., engineering directorates oversee station operations worldwide, provide technical services, and manage administrative resources. In the field, the IBB’s transmitting stations house high-power transmitters that can send radio programs to nearly every corner of the planet. Signals and Satellites The Office of Engineering transforms the words and images contained in radio and television programs into electronic signals. The Network Control Center, a hub of activity in the Office of Engineering, coordinates the flow of these electronic signals from the studio master control through many different paths to reach intended audiences. Most signals travel from a satellite dish atop the IBB’s headquarters building in Washington to leased communication satellites orbiting the Earth at heights over 22,000 miles. The satellites then send electronic signals to transmitting stations where transmitters and antennas redirect the signals to listeners or viewers sometimes thousands of miles away. Affiliate radio and television stations receive IBB broadcast signals from the leased satellites with small dish antennas located at their facilities. In many locations, U.S. diplomatic posts and cable TV systems also receive the signals. More than 1,800 satellite dishes are located in nearly 200 countries around the globe. In some parts of the world, viewers who have small satellite dish antennas can receive programs directly in their homes. The IBB has 1,304 active affiliates worldwide. VOA has 844 radio affiliates located in 86 countries, and WORLDNET Television, with 460 affiliates, reaches millions daily through satellite and cable systems worldwide. The IBB also supports the delivery of programs to RFE/RL’s 131 affiliate partners. The affiliate stations rebroadcast radio and TV programs to local audiences; they may use some or all of the available IBB programming to rebroadcast in the languages they select. Broadcast Media The Office of Engineering uses different broadcast media to reach audiences. Radio waves travel at the speed of light. The length of the radio wave, which varies from thousands of meters to fractions of a centimeter, largely determines how far and in what manner the wave will travel. Other factors such as transmitter power, terrain, and soil conductivity also affect the broadcast reach of a radio wave. Shortwave radio transmissions use the reflective properties of the Earth’s ionosphere to carry signals 8,000 kilometers (5,000 miles) or sometimes even farther to reach almost any point on the globe. Medium wave transmission, also known as the AM band in North America, can travel from 50 to 300 kilometers (30 to 180 miles) and can provide service to certain regional or metropolitan areas. At night, medium wave listeners often can hear broadcasts from stations 1,500 kilometers (900 miles) or more away. Affiliate stations also receive IBB signals for retransmission to local areas on medium wave, FM, and television channels. FM offers high-fidelity transmission but generally is limited in range to straight line, unobstructed paths. FM transmissions cannot travel farther than the local horizon (that is, to the point "where the rainbow ends") which is anywhere from 25 to 125 kilometers (15 to 75 miles) depending on the height of the transmitting antenna. For many listeners, FM is the broadcast medium of choice. This listening preference has prompted the BBG to drastically increase the IBB’s presence on the FM broadcast band. With a goal to be on the air in FM in every capital and major city in the world, the BBG has initiated a program to enhance the broadcast capabilities of existing and new affiliates by providing new FM broadcasting equipment. The BBG also is establishing its own 24-hour FM frequencies where allowed. In addition to the FM transmitters that have been operational at the IBB’s transmitting stations in Belize, Kuwait, and Sao Tome, FM facilities are now operational in Romania and Kosovo (Europe); in Burkina Faso, Kenya, and Rwanda (Africa); and in Mongolia (Asia). By the end of calendar year 2001, two more facilities in Burundi and the Congo (Brazzaville) will join this FM network. IBB Transmitting Stations From Greenville, North Carolina, to Tinian in the Commonwealth of the Northern Marianas, the IBB’s global network of stations includes about 130 transmitters with a combined power capability of more than 35 million watts. Nearly 400 antennas direct broadcast signals to audiences worldwide. With transmitting stations spanning the globe, the Office of Engineering manages facilities on over 20,000 acres of property and is guardian of more than a million square feet of buildings and structures. Some of the IBB’s transmitting stations have more than one transmitting site. The stations vary in size and broadcast capability. Twice yearly, Engineering’s Spectrum Management Division develops a broadcast schedule for the thousands of hours of programming broadcast by the IBB each year. This schedule takes into account a complex array of variables from technical considerations such as sunspot cycle and the properties of the Earth’s ionosphere to optimal listening hours of target audiences. In addition, as part of international agreements with many of the host countries that allow the IBB to operate within their borders, other international broadcasters use IBB facilities to broadcast their programs. New Technology Advances in electronics and the explosive evolution of technology offer numerous possibilities to strengthen the IBB’s competitive edge, to increase the efficiency of the broadcast network, and to bolster the effectiveness of U.S. international broadcasting. The Office of Engineering plays a prominent role in exploring, developing, and adopting many of these new technologies. Over the past few years, engineers have installed solid state modulators and other modern electronic components in many of the network’s older and less efficient transmitters. The Internet has opened a new door to audiences around the globe. Today, the IBB delivers, both live and on-demand, its entire complement of audio programming and a portion of its video programming to Internet users through a process called streaming. U.S. international broadcasters use the Internet to bring timely program material from field correspondents and monitored signals back to headquarters in Washington, D.C. More than 200 hours of programming are supplied daily to Internet audiences worldwide. Compressed audio MP3 files offer another avenue for delivery of programming. These MP3 files enable affiliate radio stations to receive broadcast quality over the Internet for their rebroadcasting of VOA programs. The introduction and expansion of use of MP3 files has allowed the IBB to transmit audio programs at a fraction of the cost of traditional means. The IBB is also examining Internet technologies that will allow users in China and other Internet-restricted countries to gain access to IBB web pages that are currently blocked from view. Although use of proxy servers offers some relief, in the long run, peer-to-peer networking techniques will need further development to overcome the jamming of Internet content by certain political regimes. IBB's efforts in the digital arena will soon take hold and enable the IBB to streamline program production in the broadcast studio and increase the efficiency of program distribution throughout the global network. Transferring news and program feeds onto tapes and the many tasks that followed–copying, editing, splicing, dubbing–will all be done through a computer or console. The IBB also is a founding and active member in Digital Radio Mondiale, an international consortium to establish a single, worldwide standard for future digital shortwave broadcasting. Digital broadcasting techniques for shortwave will rejuvenate the long-range broadcast medium by providing fidelity similar to FM and by greatly lessening the fading and interferences typical of current shortwave broadcasts.
Office of
Engineering and Technical Services
December 2001 |