As earlier, we discussed about Data Communication. Data Communication is the exchange of data in the form of Os and 1s between two devices via some form of transmission medium.

Now we will discuss about Data Transmission speed and data transmission media.

Data Transmission Speed:

  • Bandwidth


  • Baud



§  Bandwidth is defined as the amount of data that can be transmitted in a fixed amount of time.

§  For digital devices, the bandwidth is usually expressed in bits per second (bps) or bytes per second.

§  For analog devices, the bandwidth is expressed in cycles per second, or Hertz (Hz).

§  Bandwidth is used to describe network speeds, it does not measure how fast bits of data move from one location to another.


§  At slow speed, only one bit of information is encoded in each electrical change.

§  The baud, therefore, indicates the number of bits per second that are transmitted.

§  For example, 300 baud means that 300 bits are transmitted each second.

§  Basically, Baud is a unit of measurement of data transfer rate and measured in bits per second (bps).

Data Transmission Medium:

Transmission media is a pathway that carries the information from sender to receiver. We use different types of cables to transmit data.

Data is transmitted normally through electrical or electromagnetic signals.

Many Transmission media are used as Communication channel.

Data is represented by computers and other telecommunication devices using signals.

Signals are transmitted in the form of electromagnetic energy from one device to another.

Electromagnetic signals travel through vacuum, air or other transmission mediums to travel between one points to another.

Electromagnetic energy includes power, voice, visible light, radio waves, ultraviolet light, gamma rays etc.

Transmission medium is the means through which we send our data from one place to another.

Type of Transmission Medium:

  • Wired or Guided
  • Unwired or Unguided

Bounded or Guided Transmission

§  It is the transmission media in which signals are confined to a specific path using wire or cable.

§  Guided Transmission is the cables that are tangible or have physical existence.

§  Guided Transmission is limited by the physical geography.

§  This type of Transmission is called Wired Communication.

§  Popular bound transmission media in use are Twisted Pair CableCo-axial Cable and Fibber Optical Cable.

§  Each of them has its own characteristics like transmission speed, effect of noise, physical appearance, cost etc.

Unbounded or Unguided Transmission

§  Unbound Transmission Media are the ways of transmitting data without using any cables.

§  These media are not bounded by physical geography.

§  This type of Transmission is called Wireless Communication.

§  Nowadays Wireless Communication is becoming popular. Wireless LANs are being installed in office and college campuses.

§  This transmission uses Microwave,Radio WaveInfra Red are some of popular unbound transmission media.

Factors to be considered while choosing Transmission Medium:

  • Transmission Rate


  • Cost and Ease of Installation


  • Resistance to Environmental Conditions


  • Distance