Data Transmission Techniques

There are many ways of transmitting digital information through a medium. Making the choice between one technique and another is normally a question of comparison between performance, in terms of the speed and accuracy of transmission and cost.
There are two major obstacles to successful transmission : attenuation and noise. Noise can rise from a variety of sources in the environment and serves to distort the signal.
Attenuation is a measure of how much the strength of the signal is reduced in passing through the medium. It is proportional to the distance travelled.
For a particular medium, there will be a range of frequencies that can be transmitted through it.
In determining how much information can be sent through the cable, the most important aspect’ ; to consider is the width of this frequency range. This is known as the bandwidth of the medium.
Here there is a choice of baseband that carries a digital signal, or broadband that carries a radio frequency (RF) signal on the cable.
In baseband modulation, interfaces are relatively inexpensive as they require no special devices for generating the digital. Only one channel is available over the cable for communications and hence the signal can be transmitted at a single frequency at a time.