 on SSB SE generation by phase shift method in communication system. So, these are the learning outcomes the students will be able to describe the phase shift method of SSB modulation in communication system here. So, now, just recall in the previous lecture what which methods are there for the generation of an SSB. So, which method was studied in the previous lecture here. So, in the previous lecture we have seen the filter method to generate an SSB technique here. So, you know that that is in SSB we are going to suppress the carrier signal as well as the one of its sideband because the sideband contains same information in LSB and USB here. Then, so one more method is there in SSB generation that is a phase shift method here. As we know that there is some disadvantage of using an filters. So, in filters we have to do the frequency boosting. So, that is known as an upconversion. So, to remove that disadvantage. So, we have to make use of an phase shift method here. So, today so we are going to have the phase shift method here. So, we will study now phase shift method here. So, in the previous lecture we have studied the filter method. Now, this will be phase shift method here. Okay. So, in this method, so we are going to make use of two balance modulators and two phase shifting networks here. Okay. So, this method does not require any filter to generate an SSB signal here. So, that the disadvantage of using an upconversion or the balance mixer has been removed in this method that is known as an phase shift method here. So, now we will draw the block diagram for SSB transmitter with SSB modulator using phase shift method here. Okay. So, as we know that for each and every modulation you are required the modulating signal as well as the carrier signal here. Okay. So, this will be baseband amplifier. So, which is X of t modulating signal here. Okay. So, you require one that is balance modulator 1 and balance modulator 2. So, this is given directly here. One more block is there that is phase shifter by 90 degree pi by 2 which is given directly. Okay. So, this will be carrier signal phase shifter carrier. Okay. So, arrows are important in this block diagram. So, this will be an carrier signal. Okay. And this output of these two are given to adder that is given to linear amplifier to generate SSB signal. Okay. This is an output V0 here. So, now we will see that modulating signal for BM1 is directly given. So, it will be X of t that is sin omega m of t. Here X of t is phase shifted here. So, the input for modulating signal will be sin omega m of t plus pi by 2 here. Okay. So, next for this carrier signal is given directly. So, it will be sin omega ct plus only. Here the carrier is phase shifted. Okay. So, that is why it will be sin omega ct plus pi by 2. And this output will be added here and given as an SSB generation here. Okay. So, the modulating signal will be that is sin omega m of t and carrier signal will be sin omega ct. Okay. And now we will solve this equation by trigonometrical equations. So, we will see the input for BM1 what is there for and BM2 what is there here. Okay. So, for BM1 input to BM1 will be we will consider as an V1 as an output. It will be sin omega ct plus pi by 2 into sin omega m of t. So, as we have seen in this block diagram, the carrier is phase shifted by 90 degree and modulating signal is given directly here. So, that is the equation used for that. So, by trigonometrical ratio that means using the equation that is sin a into sin b. So, it will be half cos omega ct plus omega this will be plus pi by 2 minus omega ct cos omega ct plus pi by 2 plus omega m of t. Okay. So, which can be written as in half cos omega ct minus omega m of t plus pi by 2 minus cos omega ct plus omega m of t plus pi by 2. This is the equation 1. Okay. So, the first term is lower side band and second term is your upper side band. Okay. And the same way input to BM2 that will be V2 will be carrier signal is given directly omega ct into and it is given phase shifted by plus 90. Okay. So, these two equations are there. So, if you solve this equation, so it will be half cos omega ct minus omega m of t minus pi by 2 minus cos of omega ct plus cos of omega m plus t. So, this is equation 2. The first term is same here the lower side band and this will be an upper side band here. Okay. So, now if you have an output that is V0 which is adder as shown in the block diagram V1 plus V2. If you add this two signal that is equation 1 and 2. So, you will get an output that is cos. So, you are going to consider only positive value. So, that is why more and cos omega ct plus omega m of t plus pi by 2. So, which can be written as a minus omega ct plus omega m of t. Okay. So, this is the final equation. Okay. So, you are going to have the USB signal at the output here. Okay. So, the both valence modulator produces an output consisting of the both the side bands here. Okay. In both the cases that is USB leads by the carrier signal by 90 degree and you are in phase at the adder and hence they do not producing SSB. Okay. That is an USB. Okay. So, now if you want to produce the lower side band here. So, there is one change in the diagram what we have to do. So, instead of connecting the carrier signal here. So, you are going to consider the carrier signal at this position means for BM 1. So, modulating signal will be given directly and the carrier signal is also given directly here. And for BM 2 it will be phase shifted carrier signal as well as the phase shifted by the modulating signal here for BM 2 always it will be an phase shifted here. Okay. So, now, so what we are going to consider we are going to consider the advantages and disadvantages of phase shift methods. There is no need of an upconversion frequency at this stage here. Okay. And it is easy to generate and the side bands here. Okay. And but what is the difficulties is there disadvantage in this case we have to do the phase shifting for the modulating signal as well as for the carrier signal here. So, that is the one disadvantage of using the phase shift method. So, one disadvantage of an the upconversion has been removed from the filter method to phase shift method. But there is some practically problems that we have to phase shifted both the signal here carrier as well as the modulating signal. So, that disadvantage has been removed in your third method in SSB technique in which the modulating signal is not phase shifted only carrier signal is phase shifted here. Okay. So, right now you just remember that in third method there is no phase shifting of an modulating signal. There is only a phase shift shifting of an carrier signal here. Okay. So, thank you.