The transmission medium is the physical pathway for signals in a communication system. It allows the propagation of electromagnetic or electrical signals carrying information. Factors like distance, bandwidth, signal quality, interference susceptibility, and cost determine the choice of medium. Wired and wireless mediums are often combined for optimal benefits. Consideration of transmission medium characteristics is crucial for designing reliable and efficient communication systems.
In guided media signals are transmitted in a narrow pathway by using physical links. It is also called Wired or Bounded transmission media. The physical links are the cables that are tangible or have physical existence. There are three common types of guided media used for the networks. Each of them has its own characteristics like transmission speed, effect of noise, physical appearance, cost, etc.
Twisted Pair Cable: Consists of pairs of insulated copper wires twisted together. It is commonly used for telephone lines and Ethernet connections.
This type of cable can block interference but it is vulnerable to external interference. It is mostly used fortelephonic applications. It is less expensive and easy to install.
This type of cable consists of a special coating to block external interference. It is used in fast-data-rate ethernet and also in voice and data channels of telephone lines.
Consists of a central conductor surrounded by insulation, a metallic shield, and an outer insulation layer. It is used for cable television (CATV), broadband internet, and other high-frequency applications.
Utilizes thin strands of glass or plastic fibers to transmit light signals. It provides high bandwidth, low attenuation, and immunity to electromagnetic interference. Optical fiber is widely used in long-distance telecommunications and high-speed data transmission.
Unguided media is also termed wireless or unbounded transmission media. As the name implies, it does not require a physical medium such as wire for the transmission of electromagnetic signals. There are three major types of Unguided Media.
Electromagnetic waves used for wireless communication. They are commonly used in applications such as broadcast radio, Wi-Fi, Bluetooth, and cellular networks.
Electromagnetic waves used for wireless communication. They are commonly used in applications such as broadcast radio, Wi-Fi, Bluetooth, and cellular networks.
Terrestrial microwaves have both stations having antennas on earth.
Communication signals transmitted to and received from satellites orbiting the Earth. It enables long-distance communication and global coverage.
Infrared light is used for signal transmission, with LEDs transmitting signals and light-receivers (photodiodes) receiving them. It operates at terahertz frequency but cannot penetrate walls or objects. Infrared communications establish short-range wireless links using line of sight. The choice of transmission medium depends on factors like distance, bandwidth, signal quality, interference susceptibility, and cost. Combining wired and wireless media optimizes benefits in modern systems. Consideration of transmission medium characteristics ensures reliable and efficient information transmission in communication system design.
Transmission impairments degrade signal quality in communication systems, impacting wired, wireless, and optical networks. They can cause errors, information loss, or degraded signal quality, leading to system performance reduction or failure. Common types of transmission impairments exist.
Attenuation refers to the weakening or loss of signal strength as it travels over a distance. It is caused by factors such as resistance, cable loss, and dispersion. Attenuation can lead to a reduction in signal power, resulting in a weaker and less reliable communication link.
Distortion occurs when the shape or integrity of the signal waveform is altered during transmission. This can be caused by factors like frequency-dependent attenuation, signal reflections, or signal dispersion. Distortion can lead to signal loss, waveform deformation, and difficulties in correctly interpreting the transmitted information.
Noise refers to unwanted variations that corrupt the original signal, caused by sources like electronic interference or external factors. It degrades the signal-to-noise ratio (SNR) and impacts data accuracy and reliability. Techniques like error correction coding, equalization, amplification, filtering, and modulation are used to address transmission impairments and improve signal quality and reliability.