A computer network is consisted of two or more computers that are linked together using a communication medium in order to share files and resources.
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Computer network is used to transfer data between two more devices with the help of signals. Therefore, a signal is an electronic voltage or current which varies with the time, which is used to transfer data from one end to another. A signal can be divided into two categories called Analog and Digital. Amplitude, Frequency, Wavelength and Phase are known as the properties of a signal. If we look at the type of the medium that data is transmitted, it can either be guided(wired) or unguided(wireless). Twisted pair, coaxial and fiber optics are some examples for guided medium while, infrared, radio waves and satellites can be kept under unguided medium. When considering the data transmission, there are some technical words we should know.
Latency: Network latency refers to, the time it takes for a unit of data to travel from one end to another.
Bandwidth: Bandwidth refers to the maximum amount of data transmitted within a given period of time.
Noise: Noise is a received signal that makes no sense.
Attenuation: Attenuation refers to the reduction of signal's energy as it travels through a given medium.
Topology: Network topology refers to the way in which the devices are connected within a network.(for more information see page_4_)
Just like the transmission medium, there are transmission modes too. Simplex, Half-duplex and Full-duplex are those. With the advancement of the technology, these modes were developed respectively. Let's zoom in a little bit more into these modes.
Simplex: This was the oldest mode of transmission which is also known as an undirectional mode. In this mode, a sender can only send data thus, this was the worst performing mode. Keyboard and monitor can be referred as simplex mode.
Half-duplex: This is a two directional mode(one at a time) thus, sender can send and receive data one at a time. This mode can be considered as a better version of simplex. Hubs and walky-talkies are some examples for this mode.
Full-duplex: The best version which is also two directional(simultaneously). A sender can send and receive data simultaneously. Switch, telephone and router comes under this mode of transmission.
Sometimes it is needed the signals to be converted into another form, this is called as modulation, described as follows.
Ø Amplitude modulation, Frequency modulation and Phase modulation are the techniques used to transfer a signal from analog to analog with the use of carrier signal.
Ø PCM (Pulse Code Modulation) is used to convert an analog signal to digital.
Ø Amplitude shift key, Frequency shift key and Phase shift key are the techniques used to convert a digital signal to an analog signal.
