Assignment 1: Cable Testers
Wire-Map Testers
A wire-map tester transmits signals through each wire in a copper twisted-pair cable to determine if it is connected to the correct pin at each end. Wire-map testers detect transposed wires, opens, and shorts which are all problems that can render a cable useless. A wire-map tester consists of a remote unit that you attach to the far end of a connection and the battery-operated, handheld main unit that displays the results. Typically, the tester displays various codes to describe the type of faults it finds, so you know which part of the cable you messed up on or what else may be wrong with it.
Tone Generators
Tone generators are the simplest type of copper cable tester. A tone generator is made up of two parts, a tone generator and a probe. These are sometimes referred to as a fox and hound wire tracer. With a standard jack, you connect to the cable the unit that transmits a signal, or, with an alligator clip, you connect the unit to an individual wire. The other unit is an inductive amplifier, which is a pen like probe that emits an audible tone when touched to the other end of the conductor. Tone generators are most often used to locate a specific connection in a punch-down block. Using a tone generator is extremely time-consuming and it is nearly as prone to errors as the cable installation.
Time-Domain Reflectometers
A TDR is the primary tool used to determine the length of a copper cable and to locate the impedance variations that are caused by opens, shorts, damaged cables, and interference with other systems. There are two basic types of TDRs available: those that display their results as a waveform on an LCD screen and those that use a numeric readout to indicate the distance to source of impedance. You can use a TDR to test any kind of cable the uses metallic conductors. A high quality TDR can detect a