Network Wiring 
Basics

Wire and Fiber Printable Lecture

  1. General Wire Info
  2. Coax Cable
  3. Shielded Twisted Pair Cable
  4. Unshielded Twisted Pair Cable
  5. Fiber Optics
  6. IBM Cable Types


General Wire Info


Coaxial Cable


Coaxial Cable


Twisted Pair Cable


Twisted Pair Cable


Fiber Optics

  1. Fiber Optic construction
  2. How fiber works
  3. Wide Bandwidth
  4. Low Loss
  5. Electromagnetic Immunity
  6. Security
  7. Light Weight
  8. Small Size
  9. Safety


Fiber Optic Cable Componenets

Fiber optic cable

The protective covering
Surrounds the cladding and is usually composed of one or more layers of polymer. This coating protects the core and cladding (the optical fiber) from shock and other physical trauma.

Componenets from innermost to outer, respectively, are: the buffer, the strength members, and the (outer) jacket.

The optical fiber
Composed of two concentric layers called the core and cladding. The core is the light carrying part while the surrounding cladding provides the difference in refractive index necessary for total internal reflection of light through the core.

The index of the cladding is less than one percent lower than that of the core.


Fiber Optic Cable

Multi-Fiber Indoor Cable (MIC)


Single Fiber terminated with ST connector



Refraction and Reflection
Fundamentals...(1 of 4)


Refraction and Reflection
Fundamentals...(2 of 4)

If one were to stand on a pier and look directly down at a fish, the light would not be refracted, so the fish would be in its apparent position, but if one were to view that same fish at an angle, refraction of light would occur and the fish would appear closer to the surface. What appears to be a straight line from the fish to the eye is actually a line with a bend where the light passes from water into air and is thus refracted resulting in the fish actually being deeper in the water than it appears.

Fishie Refraction GIF


Refraction and Reflection
Fundamentals...(3 of 4)

Refraction and Incidence GIF


Refraction and Reflection
Fundamentals...(4 of 4)

Refraction and Incidence GIF

Light traveling from a lower refractive index to a higher one is bent toward the normal while light passing from a higher index to a lower index refracts away from the normal, as shown above in the top illustration. As the angle of incidence increases, the angle of refraction approaches 90 degrees to the normal. The angle of incidence that yields an angle of refraction of 90 degrees is the critical angle. If the angle of incidence increases past the critical angle (90 degrees), the light is completely reflected back into the first medium and does not enter the second.


FIBER OPTICS - Light...(1 of 5)

Light Propagation Through an Optical Fiber


FIBER OPTICS - Light...(2 of 5)

Internal Reflection In an Optical Fiber

Internal Reflection GIF


FIBER OPTICS - Light...(3 of 5)

Core and Cladding Sizes Fibers are usually expresed by first giving the core size and then the cladding size. (50/125 = a core diameter of 50 μm and a cladding diameter of 125 m)


FIBER OPTICS - Light (4 of 5)

The Two Main Methods of Fiber Classification are Composition and Mode.

Fiber Classification by Composition


FIBER OPTICS - Light (5 of 5)

Fiber Classification by Mode
The second method of classifying fibers is by the refractive index of the core and thus the modes that the fiber propagates.


Multimode Step-Index Fiber (Step Index)
Light reflects at different angles for different paths (Modes), the path lengths of different modes are different, thus, different rays take a shorter or longer length of time to travel the length of the fiber. The light is spread out in time. This is described by modal dispersion.

MMSI Illustration


Multimode Graded-Index Fiber (Graded-Index)...(1 of 2)


Multimode Graded-Index Fiber (Graded-Index)...(2 of 2)

MMGI Illustration

This fiber is popular in applications requiring a wide bandwidth, such as telecommunications.


Single-Mode Step-Index Fiber (Single-mode fiber)

  • Single mode Fiber carries only one mode, therfore, modal dispersion does not exist.
  • Capable of 10 Gbps and 130,000 voice channels with repeators needed approximately every 35 km.
  • Single mode Illustration


    Fiber Performance Comparisons (General)

    Based upon bandwidth, information carrying capacity, and lower losses.

    Fiber comparisons from lowest to highest:

    Glass fibers outperform plastic and a smaller core, typically means beter performance.


    Typical Fiber Characteristics


    Fiber Type
    Core Diameter
    (in microns)1
    Cladding
    Diameter
    (in microns)

    Attenuation
    (Max)

    Bandwidth
    (Max)
    Single Mode3.780 or 12510 dB/km @ 650 nm
       
    5.085 or 1252.3 dB/km @ 850 nm5000 MHz @ 850 nm
    6 ps/km2
    9.31250.4 dB/km @ 1300 nm

    0.3 dB/km @ 1550 nm
    8.11250.5 dB/km @ 1300 nm

    0.25 dB/km @ 1550 nm
    Graded Index501252.4 dB/km @ 850 nm

    0.6 dB/km @ 1300 nm

    0.5 dB/km @ 1550 nm
    600 MHz/km @ 850 nm

    1500 MHz @ 1300 nm
    62.51253.0 dB/km @ 850 nm

    0.7 dB/km @ 1300 nm

    0.3 dB/km @ 1550 nm
    200 MHz @ 850 nm

    1000 MHz @ 1300 nm
    851252.8 dB/km @ 850 nm

    0.7 dB/km @ 1300 nm

    0.4 dB/km @ 1550 nm
    200 MHz @ 850 nm

    400 MHz @ 1300 nm
    1001403.5 dB/km @ 850 nm

    1.5 dB/km @ 1300 nm

    0.9 dB/km @ 1550 nm
    300 MHz @ 850 nm

    500 MHz @ 1300 nm
    Step Index2003806.0 dB/km @ 850 nm6 MHz @ 850 nm
    3004406.0 dB/km @ 850 nm6 MHz @ 850 nm
    PCS20035010 dB/km @ 790 nm20 MHz @ 790 nm
    Plastic485500240 dB/km @ 650 nm5 MHz @ 680 nm3
    735750230 dB/km @ 650 nm
    9801000220 dB/km @ 650 nm

    NOTES:
    1 - Mode field for single-mode fiber; actual core diameter is less.
    2 - Dispersion per nanometer of source width.
    3 - Plastic fibers typically are used for distances under 100 m, with data rates up to 50 Mbits/s.

    Information source: 1993 Amp, Incorporated.


    Indoor Cables(1 of 2)

    Simplex Cables
    Contain a single optical fiber allowing only simplex or one-way communication since a fiber carries signals in only one direction.

    Duplex Cables
    Contain two optical fibers allowing duplex or two-way communication. One fiber carries signals in one direction while the other carries them in the oppposite direction. (Of course duplex communication is possible with two simplex cables)
    Multifiber Cables
    Contain more than two fibers. Allow building wide distribution. Cables are comprised of several loose-buffer tubes, each containing one or more fiber pairs; the tubes are stranded around a central strength member which helps to provide strain relief for the fibers when the cable is stressed.
    Breakout Cables
    Contain several individual simplex cables inside an outer jacket. Dielectric fillers are utilized to keep the cables positioned and a Mylar wrap containing a ripcord are contained in the jacket allowing the cables inside to be exposed with ease to desired length when needed. Typically available with two or four fibers.


    Indoor Cables continued (2 of 2)

    Duty Specific Cables, Indoor

    Light duty cables
    Light jacketed not specifically designed for rugged installation.
    Heavy duty cables
    Usually have a thicker jacket than Light duty cables to allow for rough handling during installation.
    Plenum cables OFNP (optical fiber nonconductive plenum)
    As previously discussed, plenum rated cables are for installing in plenum spaces where cabling is not enclosed in a fireproof conduit.
    Riser Cables OFNR (optical fiber nonconductive riser)
    A cable that runs vertically between floors of a building. Riser cables must be engineered to prevent fires from spreading between floors.


    Outdoor Cable

    Overhead
    Cables are hung from telephone poles.
    Direct burial
    Cables are placed directly in the ground (trench) and buried without addtional protective means.
    Indirect burial
    Similar to Direct burial but the cables are first placed in some protective space such as a conduit or duct prior to buial.
    Submarine
    The cable is placed underwater. (Includes transoceanic applications)


    Outdoor Cable


    WHY FIBER OPTICS?

    Bandwidth


    *AMP Incorporated, 1987.


    LOW LOSS...(1 of 3)

    Attenuation
    Loss of signal strength as it travels along a transmission path (medium) as expressed in decibels.


    LOW LOSS... (2 of 3)

    Illustration of attenuation in optical fiber versus copper

    Attenuation Graph GIF


    LOW LOSS... (3 of 3)


    ELECTROMAGNETIC INTERFERENCE

    Electromagnetic Interference
    Electromagnetic energy (or electrical noise) originating externally that can disrupt with normal operations of electronic equipment.

    EMI 
illustration


    ELECTROMAGNETIC INTERFERENCE IMMUNITY


    Security


    Light Weight


    Small Size


    Saftey


    The Basic Wiring Virtual Lecture by L. Scott Freudenthal