9. UTP Categories
• Cat 1
– Used for audio frequencies, speaker wire, etc. Not for
networking.
• Cat 2
– Up to 1.5Mhz, used for analog phones, not for networking
• Cat 3
– EIA 568-A Spec from here on up
– up to 16MHz
– Voice grade found in most offices
– Twist length of 7.5 cm to 10 cm
• Cat 4
– up to 20 MHz
– Not frequently used today, was used for Token Ring
10. UTP Categories Cont.
• Cat 5
– up to 100MHz
– Twist length 0.6 cm to 0.85 cm
– Commonly pre-installed in new office buildings
• Cat 5e “Enhanced”
– Up to 100Mhz
– Specifies minimum characteristics for NEXT (Near End Crosstalk) and
ELFEXT (Equal level far end crosstalk)
• Coupling of signal from one pair to another
• Coupling takes place when transmit signal entering the link couples
back to receiving pair, i.e. near transmitted signal is picked up by
near receiving pair
• Cat 6
– Proposed standard up to 250Mhz
• Cat 7
– Proposed standard up to 600Mhz
13. protective coating
glass cladding
optical fiber core
Optical FiberOptical Fiber
An optical fiber is a thin (2 to 125µm), flexible medium capable of guiding an optical ray.
Preferable because of,
• Large bandwidth, light weight, and small diameter
• Nonconductivity (no EMI & RFI)
• Longer distance signal transmission with lesser attenuation
• Security & greater repeater spacing
• Designed for future applications needs
14. Optical FiberOptical Fiber
Five basic categories of application have become important for
optical fiber:
• Long-haul trunks
• Metropolitan trunks
• Rural exchange trunks
• Subscriber loops
• Local area networks
15. Basic fiber optic communication systemBasic fiber optic communication system
16. Transmission WindowsTransmission Windows
• Optical fiber transmissions uses wavelengths in the near
infrared portion of the spectrum
• Both Lasers and LEDs are used to transmit light through fibers
• Lasers are used for 1310 nm or 1550 nm single mode
transmissions
• LEDs are used for 850- or 1300 nm multimode applications
21. Fiber Optic TypesFiber Optic Types
• Step-index multimode fiberStep-index multimode fiber
– the reflective walls of the fiber move the light pulses to
the receiver
• Graded-index multimode fiberGraded-index multimode fiber
– acts to refract the light toward the center of the fiber
by variations in the density
• Single mode fiberSingle mode fiber
– the light is guided down the center of an extremely
narrow core
Three basic types of optical fibers are used in communication
systems
