| Overview of Fiber Optic Testing | | | | There are some testing concerns in a |
| There are mandatory tests for every stage of the | | | | premises-cabling application based on the |
| design, manufacture, and installation of the fiber optic | | | | recommendations found in TIA/EIA-568A for generic |
| components, link, cable plant, and network. | | | | cabling systems and TSB-67 on testing. |
| Most fiber optic test procedures have been | | | | An important concept in testing is distinguishing |
| thoroughly tested and codified as industry standards. | | | | between the link and the channel. The channel is the |
| These standards are part of EIA/TIA RS455 and are | | | | end-to-end system, including any patch cables at the |
| being adapted into IEC standards. | | | | equipment or work area. The link is the |
| Most of these standards refer to tests of individual | | | | "behind-the-walls" cabling from the equipment-side |
| components under a variety of environmental | | | | patch panel to the work-area-side outlet. |
| conditions; therefore, only a few related to testing | | | | Testing can be done on either a link level or a channel |
| the performance of the installed cable plant. | | | | level. Installers of a building cabling system are usually |
| With data communication networks, we are primarily | | | | concerned with the link. The link forms the basic |
| concerned with three fiber optic test procedures: | | | | infrastructure for the building cabling. |
| FOTP-95 for measurements of optical power, | | | | Fiber Optic Component Testing |
| FOTP-171 for testing patch cables and OFSTP-14 for | | | | Fiber optic data links are composed of three |
| testing the loss of the installed cable plant. | | | | components: a transmitter, a receiver and the |
| Optical Fiber Testing | | | | interconnection cable plant. These components must |
| A great many tests must be performed on optical | | | | be compatible with the parameters of the intended |
| fibers. A fiber manufacturer must test a fiber to | | | | application. |
| determine the characteristics by which the fiber will | | | | The loss budget must be adequate for the expected |
| be specified. As a quality control measure during | | | | loss in the cable plant and the dynamic characteristics |
| manufacture of fibers, the manufacturer must | | | | must meet the bandwidth requirements set by the |
| constantly test the fibers to ensure that they meet | | | | network data transmission rate. |
| the specifications. Among the tests are the following: | | | | The loss budget is set by the output power of the |
| core diameter, cladding diameter, numerical aperture | | | | transmitter and the sensitivity of the receiver. On a |
| (NA), attenuation, refractive index profile and tensile | | | | static basis, this is determined by the difference in |
| strength. | | | | optical power levels, but in reality the issue is a |
| Other tests performed on fibers or on fiber optic | | | | dynamic one, determined by the performance of the |
| cables concern their mechanical and environment | | | | components at the data transmission rate of interest. |
| characteristics. Mechanical tests such as impact | | | | Continuity Testing |
| resistance, tensile loading, and crush resistance test | | | | Simple continuity testing can be achieved by a |
| the cable's ability to withstand physical and mechanical | | | | flashlight: Does the light come through the fiber? |
| stresses. Environmental tests evaluate the changes in | | | | Fancy flashlights - called visual continuity testers - are |
| attenuation under extremes of temperature, | | | | available specifically for fiber optic testing. A read light |
| repeated changes of temperature, and humidity. | | | | is easiest to see. |
| Fiber Optic Cable Plant Testing | | | | |