instructions of the manufacturer's literature. Component and cable installation will depend on the type of system to be installed.
NOTE: Always follow the installation instructions that come with each system.
In general there are four basic steps in intercom maintenance: inspect, tighten, clean, and adjust. Inspection is always of primary importance.
The components in an intercom system are readily accessible, and, for the most part, can be replaced when faulty.
With the solid-state devices of today, all maintenance programs are basically the same. One of the first and the most important factors you must take is to consult the manufacturers' recommendations and guidelines when performing maintenance on any intercom system.
Common troubles within an intercom system are normally nothing more than loose connections or breaks in the cable. If a component should need replacement, be sure to replace it with the manufacturer's suggested component.
People have used light to transmit information for hundreds of years. However, it was not until the 1960s with the invention of the laser that widespread interest in optical (light) systems for data communications began. The invention of the laser prompted researchers to study the potential of fiber optics for data communications, sensing, and other applications. Laser systems could send a much larger amount of data than the telephone, microwave, and other electrical systems. The first experiment with the laser involved letting the laser beam transmit freely through the air. Also, researchers conducted experiments that transmitted the laser beam through different types of waveguides. Glass fibers, gas-filled pipes, and tubes with focusing lenses are examples of optical waveguides.
Glass fibers soon became the preferred medium for fiber-optic research. Initially, the large losses in the optical fibers prevented coaxial cables from being replaced.
Loss is the decrease in the amount of light reaching the end of the fiber. Early fibers had losses around 1,000 dB/km, making them impractical for communications use. In 1969, several scientists concluded that impurities in the fiber material caused the signal loss in optical fibers. The basic fiber material did not prevent the light signal from reaching the end of the fiber. These researchers believed it was possible to reduce the losses in optical fibers by removing the impurities. By removing the impurities, researchers made possible the construction of low-loss optical fibers.
Developments in semiconductor technology that provided the necessary light sources and detectors furthered the development of fiber optics. Conventional light sources, such as lamps or lasers, were not easily used in fiber-optic systems. These light sources tended to be too large and required lens systems to launch light into the fiber. In 1971, Bell Laboratories developed a small area light-emitting diode (LED). This light source was suitable for a low-loss coupling to optical fibers. Researchers could then perform source- to-fiber jointing easily and repeatedly. Early semiconductor sources had operating lifetimes of only a few hours; however, by 1973, projected lifetimes of lasers advanced from a few hours to greater than 1,000 hours. By 1977, projected lifetimes of lasers advanced to greater than 7,000 hours. By 1979, these devices were available with projected lifetimes of more than 100,000 hours.
In addition, researchers also continued to develop new fiber-optic parts. The types of new parts developed included low-loss fibers and fiber cables, splices, and connectors. These parts permitted demonstration and research on complete fiber-optic systems.
Advances in fiber optics have permitted the introduction of fiber optics into present applications. These applications are mostly in the telephone long- haul systems but are growing to include cable television, computer networks, video systems, and data links. Research should increase system performance and provide solutions to existing problems in conventional applications. The impressive results from early research show there are many advantages offered by fiber-optic systems.Continue Reading