These test methods describe procedures for measuring the attenuation by substitution of short length multimode graded index and single-mode optical fiber cable assemblies. The cable assemblies have a connector on only one end of the cable (pigtail) or have connectors on both ends of the cable (patch cord). The connectors on the patch cord may be identical or different from each other.

These tests are primarily used for multimode cables of 100 meters or less in length and for single-mode cables of any length. These tests primarily evaluate connector loss since the fiber loss is usually a small portion of the total loss. For those assemblies that are long enough for the fiber loss to be a significant portion of the loss, the fiber loss will have to be taken into account when specifying limits for the measured loss.

It is important to emphasize that measurement of the loss of a given cable assembly during a factory test will not necessarily be the same as a loss measurement of the same cable assembly in actual field use. The actual loss of the cable assembly depends on the properties of all of the mating components, the orientation of the components, and the launch condition of the light as it enters the connection. In a factory test only the components that are part of the cable assembly to be tested are accessible. The connector(s) that will be mated to the cable assembly in actual field use are not. Even though factory loss measurements are not necessarily the same as loss measurements in actual field use, the concatenation test is presented here as a suitable alternative which provides an estimate of average system loss performance.

NOTE - The results of this test method are not directly comparable with those of FOTP-34, which is an interconnection device insertion loss test. This FOTP tests cable assemblies and FOTP-34 tests a complete connection (splice, device, connector set, etc.) installed between two like fibers.