TRANSMISSION MEDIA Department of CE/IT

Introduction Data is transmitted form one place to another using some transmission media. The transmission medium is the physical path between transmitter and receiver for the data communications signal energy. It is known by several alternative names such as transmission path, line, channel, trunk, link, circuit, et. The medium can be wire, air or vacuum, or optical fiber. Department of CE/IT

Characteristics of Transmission media Distance Bandwidth Attenuation Resistance Security Cast linkage Department of CE/IT

Types Transmission media can be broadly categorized into two types Guided Transmission Media Unguided Transmission Media Department of CE/IT

GUIDED MEDIA Department of CE/IT

Guided media Guided transmission media uses a ”cabling” system that guides the data signals along a specific path. The data signals are bound by the “cabling” system. Guided Media is also known as Bound Media. The three guided transmission media are as follows:  Twisted Pair Cable  Coaxial Cable  Optical fiber Department of CE/IT

Twisted Pair Cable Twisted-pair cable is a type of cabling that is used for telephone communications and most modern Ethernet networks. A pair of wires forms a circuit that can transmit data. The pairs are twisted to provide protection against crosstalk, the noise generated by adjacent pairs. Two basic types of twisted-pair cable exist:  unshielded twisted pair (UTP)  Shielded twisted pair (STP). Department of CE/IT

Twisted Pair Cable Department of CE/IT

Types Department of CE/IT

Common use Voice Telephony (including private branch exchanges) Digital Subscriber Line (DSL) in many flavors Department of CE/IT

Co-axial Cable Coaxial Cable consists of 2 conductors. The inner conductor is held inside an insulator with the other conductor woven around it providing a shield. An insulating protective coating called a jacket covers the outer conductor. The outer shield protects the inner conductor from outside electrical signals. The distance between the outer conductor (shield) and inner conductor plus the type of material used for insulating the inner conductor determine the cable properties or impedance. Department of CE/IT

Co-axial Cable Department of CE/IT

Common Uses: Cable TV (Old: RG-59; New: RG-6) Ethernet (RG-58: 10Base2; RG-8: 10Base5) Amateur radio Department of CE/IT

Fiber optic Cable Description: A thin glass core surrounded by cladding that reflects light into the core, surrounded by a protective plastic buffer/jacket. Example: Department of CE/IT

UNGUIDED MEDIA Department of CE/IT

Introduction Unguided media relates to data transmission through the air and is commonly referred to as wireless. The transmission and reception of data is carried out using antenna. These media can carry such electromagnetic signals as microwave, infrared light waves, and radio waves. Department of CE/IT

Unguided Media Department of CE/IT

Types Directional (in a beam) Omnidirectional (all around) Department of CE/IT

Laser Unidirectional High bandwidth Cannot penetrate thick fog or rain (Doesn't require an FCC license) Department of CE/IT

Infrared Mostly directional Cheap Do not pass through solid objects (so no license is required) Department of CE/IT

The End Department of CE/IT