hi friends, once again welcome back in our educational channel that is precise electronics. Friends, in today's video lecture, we are going to study the first type of modulation, and that is amplitude modulation. Friends, we know modulation. What is modulation? It is the process in which amplitude, frequency, phase, and pulse, one of the characteristics from these four, is varied with the instantaneous value of the modulating signal. Mechanical pointer, amplitude, frequency, phase, pulse, carrier. Carrier means what? A signal which has very high frequency, which is used to carry the information, carry the instantaneous value of the modulating signal. In case of amplitude modulation, it is the process in which the amplitude of the carrier signal, the high-frequency signal, is varied with the instantaneous value of the amplitude of the modulating signal. The modulating signal, it is the information. The information, it may be the audio signal, it may be the video signal, takes a cell data cell, it may be the picture sky yourself, that is. But in this case, the frequency, phase, and pulse, these three parameters, these three characteristics, remain constant. That is amplitude modulation. That is a waveform of high frequency.

carrier high frequencies so that is a high-frequency carrier signal can enter up into three waveform buckwheat. That's a modulating signal which has a low-frequency current signal like this for abcd coming in. The amplitude of the high-frequency carrier is given as an upper marker amplitude that is a while the amplitude of the amplitude modulating signal carrier sampled upon [Music]. But amplitude gets varied from minimum to its maximum value then returns back to its minimum value exactly the procedure the workings [Music] of the modulating signal is zero therefore resultants are not the resultant amplitudes or say it remains the same that is same as it remains putting a metal as the modulating voltage increases in the positive direction from a to b. Modulating signals at a to b resultant the results amplitude as modulating voltage increases in the positive direction from a to b. The amplitude of resultant modulated carrier also increases a a plus b putting from point b to c. From point b to c amplitude of the modulating signal decreases and returns

backs to its original level method over there b201 when moderating voltage changes from c to d the c to the image of the change the amplitude of moderating signal increases but in negative direction method that is changes from a plus so a plus b but b is negative so we are getting a minus b a minus b uh once again the amplitude of modulating signal increases from minimum to maximum level so once again the amplitude of resultant resultant carrier that means modulated signal is also varies from a to b amplitude a 2 a plus b a plus b a then it changes to a plus b that means from this we can conclude that in this case the amplitude of resultant varies from a to a plus b and a to a minus b in the resultant amplitude very easily happened it is known as the amplitude modulation the amplitude of result absolute drop carrier signal varies with the instantaneous value of amplitude of modulating signal i thought let's say expression buckets actually expression applied derivative expression of resultant is given by v

mod v that is the voltage and modulate modulated so voltage that is given by vc sine 2 pi fc. It is the one factor vc sine 2 pi fc t plus mavc by 2 m abc by 2 cos 2 pi fc plus fm t. What is fc? That is frequency of carrier and fm frequency of modulating signal t minus mavc by 2 cos 2 pi fc minus fm into t. Here's the expression that is the final expression of our modulated wave. The expressions are minus fm and the third method factors method that in fact where fc is a carrier frequency and fc plus fm is known as the upper side frequency and fc minus fm is known as lower side frequencies frequency model happen then upper sideband frequency and loads lower segment bandwidth minus fm and fc where fc carrier frequency fc plus fm upper side frequency fc minus fm lower cell frequency. That means frequency presence in frequencies and a pair of two sideband frequencies fc plus fm and fc minus fm. This equation shows that the amplitude

of USB upper sideband and lower sideband is equal to the A that is given by M ABC by 2. What is MA is known as a modulation index. We see that is an amplitude of carrier signal. So it is MAVC by 2 mappings of MATLAB. This amplitude of sidebands never exceeds the carrier amplitude carrier [Music]. That is given by VC voltage of carrier. Then we are getting upper side frequency LC value only FC plus FM whose amplitude is MAVC by 2. Similarly, we are getting the lower sideburn frequency frequency lower side bandwidth up and down frequency FC minus FM and the amplitude of this lower sideband is MAVC sorry it is MAVC by 2. That is known as the frequency spectrum of amplitude modulation at the importance and lower sideband. It is FC minus FM and amplitude is MAVC by 2. Information information when modulation takes place the amplitude of carrier does not remain constant but varies with time above and below the peak value of our modulated.

carrier elevation spectrums that is of each sideband is equal to mavc by two that don't side bend sample you don't see one fixed it is m a b c by two for the next point up on both way spectrum applied displacement in am is an amplitude variation of carrier due to which the sidebands are very important sidebands important guy can include various alignment carriers the sideband shows the variation of audio signal on both side of carrier wave plus fm lower 70 ta it is fc minus fm so fc plus fm minus in bracket fc minus fm fcfc cancels with the fm plus 0 minus minus becomes positive so we are getting 2fm so the bandwidth monthly there is a highlight korea so bandwidth of fm bandwidth of this modulation is 2f8 is 2f the useful power is only in sidebands in case of hundred percent modulation only one third of total power is carried by both side bands and due to which the efficiency of am is low.

happen hundred percent modulations value basically, and because of this, the efficiency of amplitude modulation is very low. I mean, that's why the amplitude modulation is not used. Instead of that, we are going for the frequency modulation. Can amplitude modulation what is drop action hydraulics up and put challenges into the study camera. So friends, that is sorry bandwidth bandwidth of fm bandwidth and sorry bandwidth and bandwidth distance bandwidth camera. It is nothing but the difference between the upper side frequency and lower frequency spectrum spectrum. The spectrometer highest frequency range and lowest frequency range. Yeah, it's also different one that is a frequency spectrum map and voice frequency modifier frequency spectrum. That is 300 hertz to three kilohertz minus three hundred kilowatt hours of difference. That is a bandwidth of that spectrum. A bandwidth is nothing but a difference between the upper side frequency and lower side frequency. Upper sideband and lower side upper side bench frequency. That is fc plus fm lower solvency fc minus fm. So we are getting fc plus fm.

minus in another bracket. We are getting fc minus fm at the fc. Fc cancel within fc plus fm minus fc minus minus become positive. So fm assumption fc. Fc cancels. So the bandwidth is given by 2fm. So bandwidth of amplitude modulation is 2fm. Numericals we have to find out the bandwidth of frequencies a particular frequency and lower cell frequency. Then by using this formula we have to find out the bandwidth of amplitude modulation. So bandwidth of ample modulation is twice that of fm. So friends that is amplitude modulation. I metal up and amplitude modulation monday in amplitude modulation. The amplitude of carrier signal carrier signal climate will happen a signal having high frequency which is in range of megahertz or gigahertz depends on the quickly communication use core to open up spectrum so that carriers can happen. The amplitude of carrier signal varies with the instantaneous value of amplitude of modulating signal and in this case the frequency phase and pulse remain constant. So friends that is amplitude modulation. But in our next lecture we are going to

study modulation index, uh, upper sideband, lower surface, uh, and fluids is activatedly happen. That is m abc by 2. That m a is known as modulation index. So friends, thanks for watching this video lecture. Bye, take care, see you again.

AM i.e. variation of the amplitude of a carrier wave in accordance with the amplitude of signal

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