The low attenuation and superior signal integrity found in optical systems allow much longer intervals of signal transmission than metallic-based systems. While single-line voice-grade copper systems longer than a couple of kilometers (1.2 miles) require in-line signal repeaters for satisfactory performance, it is not unusual for optical systems to go over 100 kilometers (km), or about 62 miles, with no active or passive processing. Emerging technologies promise even greater distances in the future.
While today's applications require an ever increasing amount of bandwidth, it is important to consider the space constraints of many end-users. It is commonplace to install new cabling within existing duct systems. The relatively small diameter and light weight of optical cables makes such installations easier and practical, and saves valuable conduit space in these environments.
Long, continuous lengths also provide benefits for installers and end-users. Small diameters make it practical to manufacture and install much longer lengths than for metallic cables: 12 kilometer (km) continuous optical cable lengths are common. Multi-mode cable lengths can be 4 kilometer (km) or more, although most standards require a maximum length of 2 kilometer (km) or less. Multi-mode cable lengths are based on industry demand.
Long lengths make optical cable installation cost effective. Optical fiber cables can be installed with the same equipment that is used to install copper and coaxial cables, with some modification due to the small size and limited pull tension and bend radius of optical cables. Optical cables can typically be installed in duct systems in spans of 6000 meters or more depending on the ducts condition, layout of the duct system, and installation technique. The longer cables can be coiled at an intermediate point and pulled farther into the duct system as necessary. ATI's designers typically plan optical systems that will meet growth needs for a 15-20 year span. Although sometimes difficult to predict, growth can be accomodated by installing spare fibers for future requirements. Installation of spare fibers today is more economical than installing additional cables later.
Another benefit of optical fibers is their dielectric nature. Since optical fiber has no metallic components, it can be installed in areas with electromagnetic interference (EMI), including radio frequency interference (RFI). Areas with high EMI include utility lines, power-carrying lines and railroad tracks. Another benefit of optical fibers is their all-dielectric cables are also ideal for high lightning-strike incidence
Unlike metallic-based systems, the dielectric nature of optical fiber makes it impossible to remotely detect the signal being transmitted within the cable. The only way to do so is by actually accessing the optical fiber itself. Accessing the fiber requires intervention that is easily detectable by security surveillance. These circumstances make fiber extremely attractive to governmental bodies, banks and others with with major security concerns.
Fiber optics is affordable today. As electronics prices fall and optical cable pricing remains low, fiber solutions are less costly than copper. As bandwidth demands increase rapidly with technological advances, fiber will continue to play a vital role in the long-term success of telecommunications.