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StarTech.com University

StarTech University offers computer enthusiasts and IT professionals a chance to learn more about new technologies and innovations in the IT world. Take some time to review the material, then pass the exam to earn your printable certificate for each course.

Course 4: Specialized Cables

Chapter 2: Connectors & Conductors

Cable Types

To physically differentiate between cable types, as far as the purpose for which they are intended, is as easy as being able to accurately identify the connectors used to terminate the cable ends. The cable shown in figure 1-1, for example is a DVI cable (noting the DVI-I connectors on both ends); the cable shown in figure 1-2 is an HDMI cable (as identified by the HDMI connectors on each end); the cable shown in figure 1-3 is an HDMI to DVI cable, as it provides an HDMI connector on one end, and a DVI connector on the other.

Conductor

To transmit an electrical or A/V signal from point A to point B requires material that is capable of physical conduction, while withstanding limitations such as attenuation and crosstalk enough to provide an adequate signal to the receiving device. As such, the conductor used, as well as the way it is arranged within a cable are two important factors in the performance of a cable.

The conductive material (wire) used in cables is measured by "gauge", and is denoted with "AWG" (American Wire Gauge — the standard unit of measurement). The larger the gauge of a wire, the smaller the diameter of the wire surface. For example, a 40 AWG (or 40 gauge) wire has a diameter that is smaller than that of a human hair, while a wire with a size of 1 AWG is roughly the size of a standard pencil. A larger gauge wire is able to conduct more electricity/signal, as it provides more conductive material across which a signal can be transmitted.

Stranded Cable

The term "stranded" refers to cable that is comprised of several small gauge wires that have been stranded or braided together to form a single wire as part of the core of the cable. In comparison to "solid" conductor cables, stranded cables provide greater flexibility, making installation easier in situations where the cable needs to be pulled through long conduits or installed around corners or sharp bends.

Solid Cables

As opposed to Stranded Cable, solid cable uses a single, "solid" conductor in each of the individual wires comprising the core of the cable. Solid cable provides better electrical performance than stranded cable and is typically used for cable runs inside walls and through ceilings, or any job that requires a long cable run.

Composition

Cable cores are typically comprised of metal, due to its natural ability to properly conduct electrical and communication signals:

Metal Conductors:

Copper: Provides high conductivity and is more cost-effective than other metals. Physical characteristics of copper also facilitate soldering or clamping of the material, making it easier to work with than silver, gold, etc. With the exception of Optical Fiber based and customized cables, all StarTech.com cables utilize copper cores, including networking cable, peripheral cables (i.e. USB cables, HDMI cables, Component and Composite A/V cables) and ribbon cables.

Silver: A better conductor than copper, but due to cost is not commonly used.

Gold: Based on cost, gold is used sparingly as a conductor, except in specialized cases. Commonly used as an external connector for terminating A/V cables etc., gold offers excellent conduction and can withstand much of the surface corrosion to which copper and silver are prone in some environments.

Non-Metal Conductors:

Optical Fiber (Fiber Optics): Typically used in long distance transmissions requiring optimal bandwidth, optical fiber is much less susceptible to attenuation and interference than its metal counter parts. Electrical signals, typically carried by metal conductors (copper etc.), are converted to light pulses for transmission then converted back to a signal that is usable by the receiving device.

One problem to which optical fiber can fall victim is dispersion - which is the unaccounted spread of optical pulses travelling through the fiber.

Other advantages of optical fiber include: Higher bandwidth (more data carrying capacity) and the ability to remain unaffected by electromagnetic interference, which can be a critical element when considering the type of cable to install in certain environments (i.e. healthcare, industrial etc.), where these hazards may be present.

Next — Chapter 3: Jackets & Insulation