What is Modulation and demodulation ? this is very interesting topic. If you want to know hidden concept in simple way. Then you are at right place. Because i am going to explain modulations and demodulation in easiest way. So that you can’t forget it.
Hence it is important for telecommunication in your real life. Because you use and listen this term daily. if you are found of radio program. Then you commonly listen 93.5FM, 92.7FM,and 90.4FM. Do you know ? what are these ?.
So in this topic you will get all answer. As well as the important hidden concept of modulation and demodulation, and what is modulation ? why modulation is needed ? . So all questions and doubts, are going to clear in simple way. Hence you need to read complete post. After learning this post, I ensure that you will never forget modulation and demodulation. So lets start.
What is difference between modulation and demodulation ?
What do you mean by modulation ?
What is modulation ?Well this is a mode of communication. Now you will ask, what is mode of communication ? So lets understand it by a practical example. suppose you want to go to your friend home, and your friend home is 500m distance.
Then what travelling communication you are going to use. What is your opinion ? probably by walking or by cycle. Now again suppose if your friend home is 30km. Then what do you think ? Which travelling communication you are going to use.
So in this case probably by bike or car. Am i right or not ? Again take a next case, if your friend home is 500km. Now tell me, what are you going to choose for travelling, probably by car, bus or train.
Suppose if your friend home is 2000km. Then what is your mode of communication probably by train or flight. Now again suppose, if your friend home is 25000km, which communication you will choose. It may be by flight only.
What is Modulation and its real example ?
So from these examples. what is your observation ? Well as the distance increases, mode of travelling is changing. Hence in similar way modulation is mode of communication. In which data are sent in efficient time, without error.
Therefor here your mode of travel like cycle, bike, car, bus, train and aeroplane is just carrier frequency/ carrier signal. And you are original data/modulating signal. now you are going to your friend home.
Hence it means modulating signal, you are welcome in your friend room. But your carrier signal (cycle, bike, car, bus, train and aeroplane) is not allowed to enter in room . So it is discarded. But think without carrier signal, you are not able to reach your friend home. So that is why modulation is required. Now i hope, you got the point, what i mean to say.
What is modulation and its types?
now come to human body, audible frequency range is 20hz to 20khz. So below and above this frequency range human body can’t listen. Whenever we normally talk, then our frequency is 3.4khz. And when you listen music, then frequency is about 14khz.
But when do you listen FM, in this case frequency is 98.3Mhz. So here frequency is in megahertz, about 4000 times above our maximum range. Now can you tell me, how do you are listening music on FM.
Hence it is clear that 98.3Mhz is carrier signal. which is carrying original song/modulating signal. So as much of higher frequency. Whenever you are using, then its means, you are using fast mode of travel.
For example if 98.3Mhz frequency, then it is like train. And if 900Mhz frequency, it is just like equivalent to Aeroplane. So that your signal can reach timely and efficiently. As i have already mentioned, at destination point carrier signal is discarded.
Only modulating signal is receive. But carrier signal is only use for carrying modulating signal. Hence modulating signal is superimpose upon carrier signal. Therefor now i hope, you are understand concept of modulation.
Why modulation is needed ?
If you want to know concept, Why modulation is needed ? Then you refer my previous topic Telecommunication fundamental . And i am going to explain here, see below diagram.
when you talk on microphone. Then your voice is first converted into electrical signal. And that electrical signal again comes into the modulator. So in modulator higher carrier signal frequency is mixed. With Original voice electrical signal (modulating signal).
By using some technique called AM (Amplitude modulation ), or FM (Frequency modulation). ) So in the modulation process signal is made with wave high frequency. And this resultant wave is amplify means bust high power.
Hence then transmitted through transmitting antenna. Such as in the form of electromagnetic wave in the space. Now other side receiving antenna detect or receive this electromagnetic wave and send to demodulator.
where mixed signal carrier is removed. And after that original electric signal becomes weak . So again it is amplify, and bust this electric signal reaches to loudspeaker. Then converted into voice signal in audible frequency range.
So this is the basic process of modulation and demodulation. Hence this is important to know. why modulation and demodulation is needed. Therefore you see the reason of modulation. For this refer the below picture.
What is modulation easy language ?
whenever you transmit electromagnetic wave. And if its frequency is very low. In other words it is having very large wavelength. Then it has very low energy. So if transmit with high frequency wave. Therefore its wavelength is short.
But it has very high energy, and its directional quality is improved. If you transmit with very large wavelength, then wave signal energy is distracted, and so at receiving antenna energy transfer is very low.
which is not detected with receiving antenna. So this is one of the reason, that we mixed high frequency carrier signal. Because at receiving antenna reach maximum transmuted energy. So that receiving antenna can detect.
And it has also some directional quality. Hence this is second reason and very important. So there are mainly two type of antenna. which is generally use for transmitting wave signal. Well are many type of antenna.
But mostly we use for transmitting purpose, only two antenna. So one is dipole antenna, and other is mono pole antenna. As you know that, dipole antenna has two pole, this dipole antenna is transmit or receive electromagnetic wave.
Hence it depends upon the length of antenna. Such a way that, electromagnetic wave wavelength must be half of the length of antenna.
Formula is given as , Antenna length ≤ (electromagnetic wavelength)/2 ≤ ? /2 .
Why modulation is required to transmit signal wave ?
Therefore for mono pole antenna.
Antenna length ≤ (electromagnetic wavelength)/4 ≤ ? /4 .
Now take an example. when you talk, then your voice frequency is around 300- 3100 hz. So suppose you speak with a sound frequency at 3000hz.
Then sound wave is generated, with the same frequency electrical signal. Which is generated by microphone. And you want to transmit this electrical signal. With without modulation as electromagnetic wave.
So you just calculate wavelength of this electromagnetic wave. Therefore you know that speed of light is electromagnetic wave. And its formula is c = ?? .
here ? = frequency = 3000 and c = 300000000 put in above equation ? = c/? = 300000000/3000 = 100000 = 100km .
? = 100km now to detect this wavelength signal. You need to made Antenna length = ?/2 = 100km/2 = 50km . So for mono pole 25km. which is physically and economically not feasible and sufficient .
But when you modulate signal. Then its frequency is increases and its wavelength is very short. So you need to made antenna short length. And this is practically feasible and economical. Hence this is second very important reason. Why you need modulation.
If you want to learn more about Telecommunication. Then refer my previous post, link is given below.