In this article we will study about electronic communication in which we will learn about elements of a communication system, IEEE spectrum, different types of wired media such as twisted pair cables, coaxial cables, optical fiber cables, and different types of wireless media such as radio wave, microwave, and satellite communication systems.
We are very well aware about the word communication it is the process of exchanging information communication between two human beings can be verbal, nonverbal, via body language or written words etc. Nowadays we use different modes of communication such as mails, SMS, video calls etc.
Communication always takes place from a source to a destination and in between them there are various elements present. So let’s see the elements of communication systems, basic elements of any communication system are the transmitter, receiver and in between them is a communication channel.
Elements of communication System:
Now the detailed block diagram of a communication system has five basic blocks the different stages of a communication system. Our input signal, input transducer, transmitter, communication channel or medium noise, receiver output transducer and the output. Let’s see each block one by one
First is an input signal the message to be transferred acts as an input to a communication system. This signal can be in any form like a sound signal, picture, speech data, video file etc
The second block is an input transducer before transmitting the input signal it is first converted into an equivalent electrical signal from its original form the device which converts an input signal of any form into an electrical signal is called as an input transducer. Input transducers like microphones are very commonly used in communication systems.
The third block is a transmitter this block increases the power of the signal and transmits it via the communication media available. A transmitter is a combination of different circuits like an amplifier mixer oscillator etc.
The next block is a communication channel it is a medium used for the transmission of a signal from one place to another. Communication medium can be wires optical fibers cables etc
The next stage is noise which is an unwanted signal which gets added with the information signal due to noise the quality of the signal degrades. Once added noise cannot be separated from the information signal thus noise is a big problem in the communication system.
The fifth stage is the receiver the operation of a receiver is exactly opposite to the transmitter. Receiver block contains different circuits such as an amplifier demodulator detector mixer etc.
The next stage is an output transducer the output transducer converts the received electrical signal to its original form that is sound picture video data etc. The examples of output transducer are speakers computer monitor etc.
The last stage is the output where we receive the signal in its original form.
Next we learn about IEEE spectrum the information signal is first converted into an electromagnetic signal or AM signal and then it is transmitted. These AM waves are also known as a radio frequency waves. The frequency of this AM wave can vary from very low to a very high frequency the entire range of frequencies of e/m waves is called as electromagnetic spectrum or AM spectrum. These frequencies were decided by the Institute of Electrical and Electronics Engineers which is an association of engineers known as IEEE. The following table represents different frequency spectrums along with their applications.
Let’s see different transmission media now communication media is the medium over which information travels from the sender to the receiver. This media is mainly divided into two types such as wired media and wireless media different types of wired media are:
- Twisted pair cables
- Coaxial cables
- Optical fiber cables
While different types of wireless media are:
- Radio wave
- Satellite communication
In wired media the signal is guided within solid wires like coaxial cables, twisted pair cables, optical fibers etc.
Twisted pair cable:
We will start with the twisted pair cables in this type of wired media two wires are twisted around each other. We have two types of twisted pair cables such as unshielded twisted-pair cable and shielded twisted pair cable. The only difference between these two types of cables is extra shield is provided in the shielded twisted pair cables. The applications of twisted pair cables are in telephone lines in digital subscriber lines DSL local area networks LAN.
Now a question may arise in your mind that why do we need to twist the wires? Twisting reduces the effect of noise or any other external interference number of twists per unit length determines the quality of the cable. Hence the more the number of twists means a better quality cable.
Second type of wired media is a coaxial cable. it consists of two Concentric conductors separated by a dielectric material the external conductor is a metallic jacket used for shielding. The practical coaxial cable looks as shown such cables are frequently used to connect set-top boxes or TV sets applications of coaxial cables are cable TV digital transmission fast lands traditional lens analog telephone networks.
Now the third type of wired media is an optical fiber cable. Optical fibers are used to guide light rays hence while using optical fibers the information signal is first converted into a light signal using LEDs or lasers and that light signal is then transmitted through optical cables. Optical fibers have two main parts of a cable such as a core and cladding. Every fiber consists of a glass core surrounded by a glass cladding of different refractive index core and cladding a covered with a protective coating.
let’s study the propagation of light through the fiber. Light follows the principle of total internal reflection when it travels through an optical fiber core when light travels from one medium having a higher refractive index to another medium having a lower refractive index it gets reflected as well as refracted as the angle of incidence theta 1 increases angle of refraction theta 2 also increases. when the angle of incidence reaches 2 the value of critical angle theta 1 equals theta C the angle of refraction becomes 90 degrees these are two is equal to 90 degrees with respect to the boundary of the two media and the ray of light travels parallel to the boundary when incident light exceeds this critical angle light no more gets refracted and the entire incident light gets reflected back into the same medium this
phenomenon is called as the total internal reflection. Total internal reflection can occur only if the following conditions are satisfied refractive index of the glass core must be greater than the refractive index of cladding. The angle of incidence must be greater than the critical angle optical fibers find applications in almost all major fields such as medical defense telecommunications networking commercial etc.
Now we will see wireless media the basic principle of wireless communication is a transmitter converts the information signal into an electromagnetic wave and transmits it using a transmitting antenna at receiver a receiving antenna receives these waves and again converts them into their original form to obtain the information signal. wireless communication is basically divided into three different types such
as radio wave transmission, microwave transmission, and satellite communication.
We will only see basics of satellite communication that takes place between the transmitter and the receiver via a satellite is called a satellite communication. A satellite receives a signal from one earth station transmitting end amplifies it improves the signal quality and radiates it back to the earth to the second earth station receiving end. A signal transmitted to the satellite is called as uplink and a signal received from a satellite is called as downlink.
Simplex communication is basically one way communication. When we are communicating such that the transmitter is sending the data and receiver is receiving the data. But it is not possible for the receiver to send information to the transmitter.
For example in television we can accept video signal or information that we are watching on the television. The television is only receiving the data. But it is not possible for the television to send that information to other devices. So this particular type of communication is known as simplex communication. It will always receiving the signal.
Duplex communication is basically two way communication for example mobile or telephone. In mobile if I calling someone then at both ends we can transmit and receive the data. So the exchange of data is from the both ends from the calling and receiving end. So that particular type of communication is known as duplex communication.
Base band communication:
A baseband means two different things in the networking field. One baseband is related to digital signal transmission where the entire bandwidth with baseband system carries only one data signal at a time. In other words every single signal would it require an exclusive use of the shared media.
When I use the media for example no one else could be able to use it they must wait their turns Ethernet is an example of the baseband system regardless of their different versions where their early Ethernet fast Ethernet or 10 Gigabit Ethernet they all contain the word base they are baseband also refers to the original range of analog signal before it is modulated to a different frequency range. For example an audio signal may have a baseband range from 20 to 20,000 Hertz. When the transmitted on a radio frequency it is modulated to a much higher frequency range AM and FM are two comma modulated technologies in radio broadcasting
Broad band communication:
Now let’s talk about a broadband the term a broadband technically refers to any type of signal transmission technique that it carries two or more different types of data in separate channels broadband signals can share one media is like a multi-lane highway two or three vehicles can share the highway side-by-side at the same time.
Broadband is also used as marketing term for internet access this meaning is only distantly related to original technical meaning in popular usage broadband internet refers to any high-speed Internet connection such as DSL cellular cable modem or satellite however the broadband definition differs from country to country in North Korea the broadband may not be qualified as the broadband in USA in summary basement is related to digital signals while broadband is related to analog signals baseband system does not allow a digital signals to share one media. Simultaneously while broadband system can transmit a different data side by side at the same time for analog signals frequency division multiplexing or OFDM is used to make analog signals share one common media for digital signals. In a baseband system time division multiplexing or TDM is used to chance me the different uses data over one common media. TDM divides time into slots or intervals and assign them equally to these users in this way everyone has an equal share in general baseband system is a chance meeting less amount of data than our broadband system.