Question

Explain in short six characteritics of Transmission Media.

List any six characteristics of transmission media.

Explain the following characteristic of transmission media:

Bandwidth

Explain the following characteristic of transmission media:

Band usage

Explain the following characteristic of transmission media:

Attenuation

Explain the following characteristic of transmission media:

E.M.I.

List characteristics of Transmission Media.

Answer 1

Characteristics of Transmission Media are as follows:

1. Bandwidth: 
   • Bandwidth refers to the capacity of a communication medium to carry data.
   • Data transmission rate is defined as the number of bits sent per second.
   • The bandwidth of a cable is influenced by the length of the cable.
   • A shorter cable can support higher bandwidth than a longer one; therefore, maximum cable lengths are specified for different cable designs.
   • If these limits are exceeded, high-frequency signals may weaken, leading to errors in data transmission.
2. Band usage: 
   • The bandwidth is shared so that maximum usage is obtained.
   • There are two transmission modes, base band and broad band transmissions.
   • Baseband devotes the entire capacity of the medium to one communication channel.
   • Broadband enables two or more communication channels to share the bandwidth of
     communication medium.
   • The base band and broad band transmission modes are shown in following figure.
     
3. Attenuation: 
   • Attenuation refers to the extent to which a signal loses strength as it travels through a transmission medium.
   • When a signal passes through a medium, a portion of it is absorbed, weakening the signal.
   • Attenuation helps determine the maximum cable length; when the signal strength drops below a certain level, noise may appear at the receiving end.
   • Repeaters are used to restore and strengthen weakened signals.
4. Immunity from electromagnetic interference (EMI):
   • Electromagnetic interference (EMI) refers to external electromagnetic noise that disturbs signals travelling through a transmission medium.
   • EMI disrupts signal transmission and makes it difficult for computers to interpret the received signals correctly.
   • A common example of electromagnetic interference is crosstalk, which occurs when a signal from one wire is unintentionally received by another wire.
   • In computer networks, a large number of cables are placed close to each other, making crosstalk a major issue in such networks.
5. Cost of media: 
   • One major factor in the purchase decision of any networking component is its cost.
   • For a new fast technology, the cost is also higher.
   • The decision depends upon the application and the standard of the resources.
   • Therefore, the network designer must settle for something which is cheaper and more robust.
6. Installation requirement:
   • Some transmission media require skilled labour to install. This increases the cost of the network, and it may cause a certain delay.
   • Before installation, we need to prepare the actual physical layout of the network.