GUIDED MEDIA (WIRED)
Guided media includes everything that ‘guides’ the transmission. That usually takes the form of some sort of a wire. Usually copper, but can also be optical fiber.
TYPES OF PHYSICAL WIRE
TWISTED PAIR CABLE
COAXIAL CABLE
FIBER OPTIC CABLE
1. TWISTED PAIR CABLE
Twisted pair cable consists of a pair of insulated wires twisted together. It is a cable type used in telecommunication for very long time. Cable twisting helps to reduce noise pickup from outside sources and crosstalk on multi-pair cables.
There are two types of twisted-pair cable
(i) SHIELDED TWISTED PAIR CABLE (STP)
(ii) UNSHIELDED TWISTED PAIR CABLE (UTP)
(i) SHIELDED TWISTED PAIR CABLE
Shielded Twisted-Pair cable and STP cable was first developed by IBM for Token Ring networks. It consists of two individual wires wrapped in a foil shielding that helps provide more reliable data transmission.
Shielded twisted pair cable is available in three different configurations:
Each pair of wires is individually shielded with foil.
There is a foil or braid shield inside the jacket covering all wires (as a group).
There is a shield around each individual pair, as well as around the entire group of wires (referred to as double shield twisted pair).
(ii) UNSHIELDED TWISTED PAIR
Unshielded Twisted Pair, a UTP cable is a cable used in computer networking that consists of two shielded wires twisted around each other. The image shows various network cables, including UTP.
2. COAXIAL CABLE
Commonly known as coax carries a signal at much higher frequencies than twisted pair. Instead of having two wires, there is a primary ‘core’ wire in the center, with an insulator, and an outer conductor that serves as a shield and insulator. Cable TV uses Coaxial Cable.
There are a few standards:
1. RG-8: Used in Thick Ethernet.
2. RG-9: Used in Thick Ethernet.
3. RG-11: Used in Thick Ethernet.
4. RG-58: Used for Thin Ethernet.
5. RG-59: Used for TV.
3. FIBER OPTIC CABLE
Fiber optic data transmission systems send information over fiber by turning electronic signals into light. It is very expensive wire more than those
Light refers to more than the portion of the electromagnetic spectrum that is near to what is visible to the human eye.
Only a very small part of it is perceived by the human eye as light.
Fiber Optics Transmission
Low Attenuation
Very High Bandwidth (THz)
Small Size and Low Weight
No Electromagnetic Interference
Low Security Risk
Elements of Optical Transmission
EE4367 Telecom. Switching & Transmission Prof. Murat Torlak
Electrical-to-optical Transducers
Optical Media
Optical-to-electrical Transducers
Digital Signal Processing, repeaters and clock recovery
Types of Optical Fiber
1.Multi-Mode:
(a) Step-index – Core and Cladding material has uniform but
different refractive index.
(b) Graded Index – Core material has variable index as a function
of the radial distance from the center.
2. Single Mode
– The core diameter is almost equal to the
EE4367 Telecom. Switching & Transmission Prof. Murat Torlak
Single Mode
– The core diameter is almost equal to the
wave length of the emitted light so that it propagates along
a single path.
