Hello, in the last 45 lectures we have talked about various microwave components and circuits. Today and in the next few lectures we will talk about antenna fundamentals and several other antennas. So, let us start with the fundamentals of the antennas. So, first of all we actually look at the radiation pattern of the antenna. So, antenna radiation pattern is defined in three dimensional 3D radiation pattern of the different antennas are shown over here. So, this is the radiation pattern for isotropic antenna. Basically an isotropic antenna will radiate equally in the sphere ok. So, it will radiate equally in all the directions. However, I want to tell you there is a no isotropic antenna in the real world. So, this is basically speaking a reference antenna for the other antennas. So, for this reference antenna we say directivity is equal to 1 which corresponds to 0 DBI. This is the radiation pattern of omnidirectional antenna. Majority of the time we say lambda by 2 dipole antenna or any small dipole antenna will have a omnidirectional radiation pattern. In fact, there are many other antennas which also have omnidirectional radiation pattern for example, loop antenna, monopole antenna, slot antenna. So, to understand in a very simple manner. So, just think about this particular pen. So, if I see this pen from this side or from this side or from this side, we will see the full length of the pen. But as we move from here and we move to the top of this particular thing here and if we look from here, we basically see a tip of the pen. In fact, you can understand the radiation pattern of dipole antenna in this simpler manner. So, what is the radiation pattern of the dipole antenna? Well it is 0 in this direction and it is maximum in this direction and then it is going back to 0 here. So, here color red implies maximum radiation and as we move along color green here implies lower radiation and minimum radiation is present in this particular direction. So, this is what is omnidirectional about. So, it is omni in this particular direction and it is directional in this particular direction that is how the name omnidirectional antenna comes into picture. You can also understand this in another simpler manner. Let us say if we have a current carrying conductor, then how will be the magnetic field? Magnetic field will be uniform in this particular direction. So, that is what we have we have a current carrying dipole antenna and we have a uniform field in this particular direction. The third type of the antenna which is known as directional antenna, here I have given an example of a microstrip antenna array. You can see that there are several elements of microstrip antennas are there in this direction as well as in this particular direction. So, this is a planar microstrip antenna array. The reason why I am showing you this this particular antenna has a directivity of 500 which is about 27 dbi. How do we get this? You take 10 log 500 which is 27 dbi. Compare this directivity with the directivity of omnidirectional dipole antenna which is only 1.64 corresponding to 2.1 dbi. So, you can see that by using arrays of the elements we can increase the gain significantly. So, let us look at 2D cut of the antenna. So, here is a typical directional antenna. So, let us define various terms over here. So, this is a major loop and these are all the minor loops are there. Minor loops are classified again in 2 parts and that is side loops and then back loop. So, back loop is in the backside of the main beam and side loops are along the side of the main beam. So, we define certain quantities over here. So, one of the quantity which we define is half power beam width. So, half power beam width is defined where beam maxima reduces to half of its value. So, this angle here is half power beam width and then if you see this pattern goes through the null and then there is a side loop. So, beam width between the first null is defined as f and b w. Now, generally speaking beam width between first null which is f and b w is approximately equal to 2.25 multiplied by half power beam width. However, if you read different books they actually say this is approximately 2 times, but I have checked for different antennas I have found this number gives better result for f and b w. Then these side loops generally should be less than 20 dB for satellite and high power application. I just want to mention here these are actually negative value. So, do not get confused actually speaking side loop levels are minus 20 dB below the main beam ok, but generally speaking we still write as side loop level less than 20 dB. So, what 20 dB less implies it implies 1 by 100. So, just think about a high power application if we are transmitting let us say 1 kilowatt of power 1 by 100 of that will be 10 watt power going in the undesired direction. For some of the defense application power transmitted may be 1 megawatt pulse power. So, in that particular case 1 by 100 will be 10 kilo watt of pulse power going in this particular direction and that may create lot of harm to the people or to the equipment in that particular region. Hence for high power we definitely want side loop level should be much less than minus 20 dB. Similarly for satellite application also we would like side loop levels to be low because if we are looking at this particular satellite and if the side loop is high then it may pick up the signal from the other satellite also. Generally speaking we want front to back ratio also known as f by b to be greater than 20 dB. So, this is the front this is the back. So, the ratio of the two should be generally greater than 20 dB. Now how do we define directivity of the antenna? Well directivity of the antenna is defined as maximum radiation intensity divided by average radiation intensity. So, just think about this is the spherical pattern for which we have mentioned directivity is equal to 1 and this is the let us say pattern for a given antenna. So, directivity is defined as maximum value in this particular direction divided by the average value which is u 0. So, that is how we define u max divided by u 0. So, now u 0 can be represented in terms of p radiated divided by 4 pi. Why this expression? Because if we assume that power is radiated equally in all the direction. So, we know that the area of the sphere is equal to 4 pi r square. So, if we take r as 1 then we can say average radiation intensity will be p radiated divided by 4 pi. So, this directivity expression is simplified to 4 pi divided by this is known as capital omega a. So, capital omega a is beam solid angle and this particular thing can be approximated as product of theta e theta h. What is theta e? Theta e is the half power beam width in the e plane and theta h is half power beam width in the h plane. Generally speaking this e and h planes are perpendicular to each other. So, suppose if we talk about this as e plane then this will be h plane. Now of course, there is a longer expression for this particular term over here. So, this particular expression is used when we calculate e theta and e phi. We will show you in the next lecture how to calculate these e theta and e phi for a given antenna. But right now we will use this particular expression over here. So, you can see that this is relatively simpler expression. So, let us see now how this particular expression can be used further. So, directivity of small antenna is given by this particular thing over here. Now you might wonder earlier we had theta e and theta h in radian. Here theta e and theta h are in degree. So, what do we do? We simply convert pi radian equal to 180 degree. So, if you just do the conversion you will get this particular number. Now this particular expression is good generally for small antenna, but for larger antenna directivity is given by this particular expression here. You can see that this number is slightly smaller than this particular number here. The reason for that is for large antenna there will be many side lobes. So, lot of power will be going to these side lobes and hence directivity decreases. Hence, we use this particular expression for directivity. Directivity is also defined in terms of 4 pi a divided by lambda square where this is effective area of the antenna. So, larger the antenna larger will be the directivity. You can also see that it also depends upon lambda. Lambda is given by c by f. So, that means, higher the frequency smaller will be lambda. So, that means, for smaller value of lambda directivity will increase. So, remember it is not the physical dimension which is important it is actually the normalized value which is important. For example, if we have a rectangular aperture then area effective will be something like L multiplied by W. So, now you can think about L by lambda and W by lambda or if we have a circular aperture then area will be pi R square. So, again we can write as R by lambda and R by lambda. We also define another quantity which is gain. Gain is given by efficiency multiplied by directivity. So, we will see some of these things as we move forward. The next thing which we are going to define is polarization of antenna. So, there are 3 different types of polarization linear polarization, circular polarization, electrical polarization. So, how do we get these polarization? So, one has to see a total electric field may have E theta component and E phi component. So, this is E theta component this is E phi component and between the 2 components there may be a phase change which is given by alpha. Now, we will take 3 special cases if alpha is equal to 0 or pi then what will happen? This expression will become cos omega T. So, that means, this one here and this one they are kind of varying or you can say these are in the same phase. So, you can see there this is E theta this is E phi. So, as E theta increases E phi increases. So, hence there is a linear polarization. In case when alpha is plus minus pi by 2 and E theta is equal to E phi then what will happen? This is E theta and this term will be equal to this term over here and then we can say omega T now is plus minus pi by 2. So, this expression will become sin omega T. So, this is cos omega T, this is sin omega T and if you plot that we will get circular polarization. If E theta is not equal to E phi in that particular case we will get elliptical polarization. So, from here we define axial ratio of the antenna. So, axial ratio is defined as major axis divided by minor axis. So, if axial ratio is equal to 1 then it is circular polarization. If axial ratio is between 1 and infinity then it is elliptical polarization and if axial ratio is infinity that will be linear polarization. You can actually think about that for linear polarization if this is the major axis what is minor axis that is equal to 0. So, major axis can have any finite value, but minor axis is equal to 0. So, that will give us axial ratio equal to infinity. This is the typical axial ratio plot of circularly polarized microstrip antenna. When I talk about microstrip antenna we will give you little bit more detail, but over here you can see that this is axial ratio versus frequency. I have drawn a line at 3 dB. So, generally speaking axial ratio bandwidth is defined for axial ratio less than 3 dB and in this particular case we can say that bandwidth is equal to 380 megahertz which is 13 percent. So, I just want to tell you perfect circular polarization is defined for AR equal to 1. However, up to AR less than 3 dB it is acceptable as circular polarization. Let us now look quickly at input impedance and VSW or of antenna these things have been covered earlier also. So, let us just go through it quickly. So, input impedance can be RA plus JXA where RA represents power loss from the antenna and XA gives power stored in the near field of antenna. Now, RA can be divided into two terms one is RR, second one is RL. RR is the useful resistance which represents radiated power from the antenna. RL represents losses in the antenna these can be conductor losses or dielectric losses. So, we define radiation efficiency as RR divided by RA which is nothing, but equal to RR divided by RR plus RL. It is better that we design RL to be as small as possible or we can say other way that RR must be much greater than RL. So, that we can get high efficiency. Now, reflection coefficient is given by this particular expression and VSWR is given by this expression. Now, majority of the time for antennas we define VSWR bandwidth for VSWR less than or equal to 2. However, for some stringent application this could be less than 1.4 or 1.5 ok. So, depending upon the application you have to design the antenna accordingly. So, let us take an example of a microstrip antenna which we had designed at 5.8 gigahertz. So, when we talk about microstrip antenna later on I will talk about this antenna in a more detail, but today I just want to tell you what are the VSWR bandwidth and radiation pattern for a given antenna. So, this antenna was designed at 5.8 gigahertz. So, just to tell you quickly. So, what we have here this is a ground plane and this is on top of the ground plane a rectangular patch. So, just think about a ground plane here and a patch on top of that. We have already talked several microwave circuits. So, it is very similar to that and this one here is the feed point. So, we have used a coaxial feed to feed the antenna such a way that at the desired frequency input impedance should be around 50 ohm. So, this is the plot on the Smith chart as frequency changes impedance changes. This is the reflection coefficient plot and you can see that as frequency changes reflection coefficient is varying and in this particular case we define bandwidth for S 11 less than or equal to minus 10 dB it is approximately equivalent to VSWR less than 2. So, bandwidth in this case is about 85 megahertz which is 1.5 percent. In fact, microstrip antennas are known to have smaller bandwidth. However, later on I will talk about several broadband techniques where we can increase the bandwidth of the microstrip antenna. So, these are the radiation pattern gain and efficiency of this particular antenna. So, you can see that the radiation is in the broad side direction and the back radiation is relatively small and for this particular antenna we can actually calculate half power beam width in the E plane which is shown with the black teller that is 80 degree half power beam width in the H plane is 88 degree and this is the gain plot with respect to frequency and I have drawn a line which is about 1 dB below this generally 1 dB gain variation is acceptable. So, in this particular case we can say bandwidth is about 126 megahertz. Now, one can see here radiation efficiency shown by purple colour. So, that is what is the radiation efficiency. So, radiation efficiency you can see is very high that is about 85 percent or so. Now, this is the total antenna efficiency. Now, this antenna efficiency is changing it is very similar to the change in the reflection coefficient. Now, let us see how we can increase the gain of the antenna. We can increase the gain of the antenna by using large number of elements. So, here is an example of 8 by 8 electromagnetically coupled microstrip antenna array. I just want to tell you what is electromagnetically coupled. So, basically here there is a one patch we put another patch on top of that. So, these two patches resonate at nearby frequency and this whole thing is done to increase the bandwidth of the antenna. As I mentioned in the previous slide the bandwidth was very narrow, but by using electromagnetically coupled antennas we can get bandwidth of 15 percent or even 20 percent. So, for this 8 by 8 array I just want to show you. So, this is where the feed network is there. So, recall we had discussed about power divided. So, you can think about this is nothing, but a 2 way power divider another 2 way power divider and then there is a connection here. So, if you look from here this becomes like a 4 way power divider and this is the central point. So, you can see that from this central point all these power divider networks are spreading and feeding all the 8 by 8 elements which comes out to be 64 element. So, really speaking this is an example of 1 is to 64 power divider. So, this is the top layer of the fabricated antenna and I have just shown here gain plot. You can see that the gain has increased significantly compared to the gain of a single element. Here the gain is around 24 dB, numeric value of that is 250 and again for 1 dB gain variation. If you look at the bandwidth that is huge bandwidth which is equivalent to 5.4 gigahertz, but at millimeter wave frequency. I just want to mention that 5G communication may take place in the millimeter wave band. So, this kind of an array would be extremely useful for 5G and IOT applications. Here I have shown radiation pattern of 8 by 8 MSA array. So, this is the Cartesian plot this is polar plot. So, this is you can see here there is a main beam is in this direction these are the side lobe levels. Let us see the Cartesian plot. So, in Cartesian plot we basically show the angle along the x axis and this one here is the normalized value of the gain. So, you can see that here everything is normalized to 0 dB ok. So, from 0 dB you can see there is a variation over here. So, this is main lobe these are the side lobes and this one here is the cross polar component. Generally speaking we would prefer cross polar component to be as small as possible and you can see that along the main beam direction cross polar level is very very small. So, let us see what are the half power beam widths in the 2 plane for this 8 by 8 array. Since this is a symmetrical 8 by 8 array half power beam width in E plane and H plane is equal to 8.8 degree. In this case first null beam width is equal to 20 degree. So, if we take the ratio of the 2 that comes out to be 2.27. Now, we can use the directivity expression to find out the directivity. So, see this particular expression I have used 32400 value which is valid for larger array. You can see that 8 by 8 array is relatively a larger array. So, half power beam width in E and H plane is 8.8 degree. So, we substitute that value and this comes out to be 26.1 dB i whereas, simulated directivity is 25.8 dB i. So, you can see that this is the very simple calculation predicts the value of the directivity within a very small fraction of error. Now, in the next lecture I will talk about various antennas. We will start with dipole antenna I did mention what is a dipole antenna today. So, you can think about a dipole antenna like this and we had also talked about the radiation pattern of the dipole antenna. It is omni in this particular direction and it is varying like a figure of 8 in this particular direction. So, this is known as E plane radiation pattern. This is known as H plane radiation pattern. Monopole antenna is half of the dipole antenna. So, whatever things are applicable to dipole they can be modified to monopole antenna. We will see that loop antenna. We will see that small loop antenna is equivalent to magnetic dipole antenna. So, whatever is applicable for dipole antenna all you have to do it is make E plane as H plane and H plane as E plane. Slot antenna is complementary antenna of dipole antenna. So, again whatever is E plane it will become H plane and H plane will become E plane. Then we will talk about linear and planar arrays. So, basically linear array is antennas arranged in the linear fashion planar arrays will be antennas arranged in the plane. So, there may be different elements now planar array can be your rectangular array it can be triangular array it can be circular array. So, basically we use arrays to increase the gain of the antenna. I did show you an example of a microstrip antenna today. We will talk in detail about these microstrip antennas later on. Then we will talk about helical and horn antennas. So, helical antenna is nothing, but you take a wire and a wrap it around ok that forms the shape of helix. So, that is that is what is a helical antenna. A horn antenna can be a pyramidal horn antenna or conical horn antenna. So, typically there are different types of horn antennas that could be in rectangular shape or it can be in the shape of circular. So, generally speaking in the rectangular shape we will talk about H plane sectoral horn antenna, we will talk about E plane sectoral horn antenna and pyramidal horn antenna. In case of circular we will talk about codical horn antenna. Then we will talk about three different types of antenna here. Yagi Uda antenna is known by the name of the inventors. So, Yagi Uda antenna is generally used to increase the gain of a dipole antenna. Log periodic antennas are generally used to realize very broadband antenna. We can even design antennas with the bandwidth ratio of 1 is to 10 or even more. So, that means, one log periodic antenna can cover a bandwidth of 3 to 30 gigahertz or 1 to 10 gigahertz or 300 megahertz to 3 gigahertz. Then we will talk about reflector antennas. In reflector antennas we will first talk about corner reflector antenna and then we will talk about parabolic reflector antenna. In fact, reflector antennas can give much larger gain than any of these antennas. In fact, reflector antennas can give gain of 40 dB, 50 dB, 60 dB and even up to 70 dB. Just think about 60 dB gain corresponds to 1 million ok. So, you cannot realize an antenna with a gain of 1 million by using reflector antennas. So, these various antennas will start discussing one by one starting from next lecture. So, thank you very much.


Dear students, I hope all of you are fine. Today, we are in the lecture number 23 of the database management system course and you know the course code is CS403. In the lecture number 22, the previous lecture, we were discussing the physical database design. This is the stage when we are at the stage of implementing our logical database design. We have got our normalized logical database design. We have passed through all the phases, say initial study, then conceptual database design, then logical database design, then normalization. But now is the stage when we are going to implement our design, our database practically. At this stage, our concern is to include the efficiency factor in it. See normalized relations, they give you an efficient design, fine. They give you an accurate, a technically sound design, that is fine. But when you are at the stage of implementing that design, now you think once again that now practically the implementation stage has come. At this stage, if you say you want to make it efficient, you have to negate it. Why? Dear students, I also mentioned in the previous lecture that this stage that we are studying nowadays that we are studying in this lecture, here you will get different options and mind it, they are options. No one will ask you to adopt a particular option. It has to be your own decision, your own analysis. You use the requirements base, the working of the database, you decided what particular option to adopt. For example, we studied one thing as coding. Coding is an option. No one will ever ask you adopt the coding or you should adopt the coding at this particular field or this particular attribute. No one will ask you. It has to be your own decision. If there is a significant difference between the storage that has been consumed by the database, then rather than storing the attributes as a whole value, you store the course. Again, the situation is that the domain of that field should be relatively small. So, this means that the things that you will see in the future, please do not get confused about what we are doing. You are just studying different options and the advantage of them is that they are studying. At every stage, when you are designing a particular database, you should look at every stage and see if you should implement that step in the physical database design. What difference will it make? What situation should we do? So again, this is your decision that you have to make. And in this, with the passage of time, with experience, you will feel very easy in making this decision. This is not a dangerous thing to be afraid of. But at this stage, it is important to know that there are different options that you can adopt at different stages. In the previous lecture, in the physical database design, we studied data volume and usage analysis. And secondly, we studied how we design fields. And on that, we studied how to allocate and assign the data type. And in addition, we studied the implementation of different integrity control. Today, we will see where we will start. Physical records and denormalization. For example, I said that you have got your logical database design, rather you have got your normalized database design. Now from here, when you are implementing it, when you are practically defining the record into some tool, into some DBMS, then these will be your physical records. So here, on a bus stage, you will adopt a concept, a practice, that is denormalization. It is strange that just at the previous stage, there was normalization, where you normalized the tables. Why? To get a smart and efficient design. At this stage, we are saying that now we are going to denormalize them. Again, mind it, two things. Efficiency purposes, where we feel that things will become efficient by denormalizing them. And secondly, again it is an option. No one is asking you to do that. Mind it. Now denormalization means that you denormalize and unnormalize the tables. Why? How? Let us see. In logical database design, we group things logically related, accessed through the same primary key. The basic approach was that we combined those things in the form of a relation, or in the relationship. And those things were normally accessed through the primary key. So now, in physical database design, fields are grouped as they are stored physically and accessed by DBMS. What is the difference? There is a link between logical and relationship. Those things are accessed through the primary key. That is the main concern. And you group those things. Here, you have to store them physically. In that way, you will combine them. And in that combination, in some cases, you will deviate from that that what you designed in logical database design, in some cases, not in most of the cases. What are the situations? When we deviate from that routine, that approach, why? For the efficiency purposes. In some cases, for the efficiency purposes, we have to denormalize the relations. Process of transforming normalized relations into unnormalized physical record specifications. What is denormalization? It is its definition. Process of transforming normalized relations into unnormalized physical record specifications. So, you will adopt this process during your physical database design. In general, it may decompose one logical relation into separate physical records and combine some and both. What will happen in denormalization? In logical database design, when you have created your own relations and normalized them, you have got no different relations. Thus, 15, 20, 50, 100, whatever depending on the size of your system. So, you have different number of relations. Now, the way you related them to their functionality and logic, you have divided them into different relations. What will happen in denormalization? You will mix some of them together. When you mix the normalized relations together, they are basically in an unnormalized form. So, you have denormalized them. Similarly, you may have got a single relation which will decompose the logical database design. So, you have denormalized them. Or there will be a combination of the two. You will break some of them together. This is how you will do this activity in denormalization. Again, I am telling you again and again that this is an option. You are not forced to do that. You will not be asked to do that. You will feel that if I do this, the efficiency will increase. The symbol of efficiency or data processing efficiency is not a complex thing. You can simply understand that if user queries are being responded relatively quickly, in less time, if the user queries can be processed, you will say that it is okay. It has become efficient. Even if you have to do more work as a developer as a developer, but if the response time for the user is increased, it means that you should take that decision. Now, here you will see three different situations where we should think that let us denormalize the thing. For example, merge two entity types into one with one-to-one relationship. For example, it is written that we have two entity types. We are talking about the conceptual database design. When we transformed them into the logical database design, you will remember that when there is a one-to-one relationship, what happened is that the participating entity types became relations. And the primary key of any one was added in the other form. We have already read which key it was. Even if one of the entity types is optional, so joining can lead to wastage of storage. However, if two access together very frequently, then merging might be a wise decision. You have one-to-one relationship. You have made two tables in normalized form. The compulsory side you had, the primary key was added in the optional form as a foreign key. Now, you had two normalized relations. Here, they are saying that you should merge them in that place. The two of them are one-to-one relationship. You should merge the two relations. The relations that were formed because of one-to-one relationship, you should merge the two entity types and form one relationship. What will happen is that if you have an optional, a compulsory one, like in most of the situations, then the option that you have when you merge them will be in the cases in which the optional side does not exist. In those cases, you will have empty fields with null values. When there are null values, it means there is a wastage of storage. But it is said that if there is a lot of joining between them, then combining them is an efficient decision, a good decision. Why? That is why, when you have accessed a table, now you want to access the related data that is stored in another table. In that case, you have accessed a table in memory. Now when you have to pick the related data, you will have to perform another read. You will have to go to another table. You will go there and pick it. Then you will find the related data and access it there. Then you will display them together. As you can see in the example. But if you join them, merge them, the advantage of that is that both fields are accessing them in the same record, in the same table. This will happen. The other thing is that the related attributes you do not need to find them in two separate tables. Rather they are there in the same table. So based on these two advantages, your efficiency increases in the access of the data. For example, in front of you, in the slide, you are saying a one-to-one relationship. There are two entity types here. Student or scholarship application. The scholarship application side is one option here. This means that in the real-life situation, not necessarily every student will apply for the scholarship. So this side is optional. And obviously the application should be linked with some student. So that side is compulsory one. In this situation, obviously if you want the student's data and also the application data. For example, if you want student's address and its application date and qualification. In this case, when you implement it practically in these two separate tables, as you have done it in the normalized tables, that you have made these two tables, the problem will be that when you want student's address, his qualification and application address, you will have to go to the student table and read one, pick the data from there, and then you will have to read the student's ID and then go to another table. You will have to go to another table. From there, you will read the table again. And then you will search for the relevant data in this table. There are techniques that make the search very efficient. In one-to-one cases, the searching becomes quite efficient. But still, you have to go to the second table and you have to read that. Now if we merge these two, we will do we make a single table. In this table, we add a single relation of 2k. In this, we put the student ID as primary and campus address, application date and qualifications. Now the application ID here, if we need it as a data, then we can store it. But if it was being used only for the identification of the application, in that case, you don't need to store the application ID. So it's up to you or it's up to the requirement that now in this case, when you have merged these two relations, in this case, you don't need the application ID. In other cases, the student ID was used as the primary key and the rest of the data and the rest of the attributes of the scholarship application were made into a single table. What is the loss of this? The loss is because it was the situation that not every student applies for the scholarship. This means that when you enter the data, to those students in this merge table, those students who have not applied for the scholarship, for them, the attributes related to the scholarship application, they will be null. So this is a wastage of storage. Fine. Agreed. But see the advantage. Advantage is that when you want to access both of them together, the student data and the scholarship application data, both are there in the same table. Now where do you see what species you will make this decision? The first thing is that if those people who do not apply for the scholarship, their number is very low. You say that the students who apply for the scholarship, they are too much, or most of the students apply for the scholarship. This means that in this case, the null values of yours will be very low. For example, if we have thousands of students who we have data stored in, and 700, 750, 800 people who apply for the scholarship. This means that most of them, they are applying. So the data wastage is not there. That is not that much. Okay. There is a loss, but there are so many records where the null is not there. This is the situation. In this situation, we should consider merging them together. One thing. Secondly, if both of them, the student data and the application data, if they are accessed very frequently in many applications together, in that case, even if your wastage is too much, even then, you can think of merging them into the same table. Why? Because your maximum application, which is running in many applications, and they are accessing them together, they become efficient at the expense of storage. If this is not a big story, or even too much, if it matters, and even feels satisfied with the customer, and the customer will not tell you directly that you can spend money on it, or calculate it, or you can take feedback from it, in any case, if you feel it counts, its values, or on what basis, that both of them are accessing in many applications, then go for joining them. I hope you understood this situation. Let us go ahead. Let us see what is the second situation where denormalization is recommended or is suggested. Many to many binary relationships mapped to three relations, queries needing data from two participating data types joining of three relations, that is expensive. Let us see one thing, that when we will read about query processing at some stage, then we will see what is the cost of executing different operations. We have read about joins. What joins is that from two different tables, the data is combined with the related data, and the relationship is established on the basis of the same value of the common attribute between two tables. This is a join operation. A join operation, from the execution point of view, is an expensive operation. It takes time. It takes resources. Why? First, you have a table of a student, and against that, we have courses. This is the courseman role. If we talk about two tables, what will happen in that case? If you have stored the foreign key, the primary key, you will first take a record of the foreign key, and with the foreign key, you will try to match it from the other table. In this way, you have to access the other table and search for the value. It takes time. In bigger tables, it can be quite expensive time-wise. In this way, a general rule is that a join is an expensive operation. It takes resources and time. Now suppose that we have a many-to-many relationship. As I was reading the rule of mapping, the participating entity is in the binary case. We transform the participating entity into the relations. We also implement the relationship of the relationship as a relation. Generally, the primary key of both the relations is used as a primary key of this third relation. The first thing we have is that we have a student course, and there is a relationship of many-to-many. Now you have three relations. First, we want which student needs the student's name, and which courses are enrolled in. Again, student, courses, many-to-many relationship. We have transformed the student's relationship, the course's relationship, and the relationship of many-to-many between them. Let us say, an enrolled relation. We have three relations. We need student name and the course's name. Now what is happening? How will this happen? First, you will take the student's ID from the student table. After that, you will join it with the enroll. In enroll, the records in which the student's ID and enroll records are found, you will identify them first. After accessing them, you will get the courses ID from the enroll. Because courses ID, and enroll is a relationship table, which was made by the relationship. There will be both the primary key, both the students and the course. Now, the courses in which the student's ID and the course are both present in the enroll. So, first, you will take the courses from the student. Then, you will take every course and merge it with the course. So, you take the course ID from the enroll, and merge it with the course. Then, you will get the course's name. This means you will have to join three tables. Students with enroll and enroll with the course. So, you will have to join these three tables. This situation is a recommendation to avoid it. How? The relationship created against a relationship is merged with one of the relations created against participating entity types. As I just told you, the third relationship you created which we have enrolled, you merge it with one of them. What is the advantage of this? The advantage would be that rather than joining between three tables, you will have to join two of them. Now, you will have to join just once, between two tables. Because we have not got three tables now. Now, we have got two tables. And you will have to join between these two tables. This difference is made in this situation. But, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, but, against, we created the third table, work. Because we need work, we have got the situation that one employee can work on many projects, on one project, many employees work. So, this was made into many to many, and that many to many relationship against your work table was created. As you can see, the employee ID and project ID are primary key of work, and date hired or salary. These are the descriptive attributes of this work table. This is our normalized relation. And this is the same situation that when you want a certain employee name or a certain employee to work on which project and which date was hired. Now for this thing, you need to merge three relations, two joints that are involved. When we denormalize it then the rule is that you merge the work relation with one of the two relations. In this case, we have a small project relation, and since there is a repetition in this, we merge this with the work relation with the project relation. With that, you will have two relations. One will be your employee and the other will be the project. Now, the employee's data came into this, the work data came into this. What is your table? Your project table has project ID, project name, employee ID, date hired or salary. And this table, which is your project table, now the primary key for this table will be project name and employee ID. And if I ask you which normal form this relation is violating, clearly second normal form. Why? Because your project name is being determined by the project ID only. What does this mean? You have that violation of second normal form so we can say this is an unnormalized table. What is the benefit of this? The benefit of this is that the time you want that the employee is working on which project and what is the name of the project and which date was hired on that project. You simply take the ID of the project from the employee table and you take the join yet you merge it with the project. Now the project table contains the project data also the hiring detail of the employee on that project. So you will get two things from this table. The name of the project and the employee who was hired and salary what is the benefit? The benefit is that now you have to join two tables rather than three tables. So that efficiency is of great use. What is the loss? The loss is that whatever second normal form anomalies were, now they are there. There is redundancy in this because the project name is being repeated. This means that if on a project 100 employees are working, then the project name is being repeated 100 times. The inefficiency is there. But look at the advantage. The advantage is that the very frequent queries on which the employee is working on which project and which date was hired and what is the salary. Now that is being retrieved very efficiently. There is redundancy, insertion normally there is, deletion normally, updation normally but if you see the situation that normally updation is not frequently done. For example, the project name, you say that it is not frequently changed. So if it is done then you know that you have to do it all. Similarly, if you see that this issue has come forward, a very serious thing is that you cannot enter a project into this table unless an employee is assigned to the project. So knowing the drawbacks then you see that the advantage does it outweigh the drawbacks? If the advantage is more and drawbacks is less then you should go for that. So this was the second situation in which we should do the denormalization. Let us go ahead. Denormalization is situation 3, reference data. One to many situation when the entity type on one side does not participate in any other relationship then many side entity type is appended with reference data rather than the foreign key. This situation which we have mentioned here is from the class that we have read about coding it also covers the coding situation which we are going to negate. And this very frequently happens in the normal logical database design. You do that instead of having a table on many side on one side you repeat the value of the table on one side and put it on many side as a foreign key and it also covers the reference. So in some cases you can see that if your reference table is not involved in any other relationship and its purpose is to work as a reference in your table in that case you can put that reference table through id and put the data into the main table. You can see the student and the hobby as an example. We have already seen that if you have got a student table and one student can have one hobby, so one hobby can be obtained and can be acquired by many students. So this is one to many relationship. First we have done this routine, we have talked about coding. We have said instead of placing the hobby there we were placing just their codes. Now we will reverse this because we will have to balance that what is the drawback in coding? That we have to access two tables and then we have to join them to find the value. So here we will do that we place the value straight away. Now the loss is that your storage wise is getting wasted because the values take more space as compared to the advantage that rather than accessing two tables and merging them to get the required information, you get all the information, all the data in the same table. So this is the situation where we merge one to many. Dear students, we have studied different options of the denormalization. I will say again that always see what are the advantages, what is the benefit that you are getting from the denormalization and also calculate the drawback, the extra work the possible types of error that could happen due to this denormalization. Now compare both of them. If you are getting benefits from this denormalization, if it is more and its cost in terms of extra processing, in terms of extra storage or in terms of risk storage, it is fine that you will manage extra space in that but the extra risk of this inconsistency, that you have to manage. There is a duplication drawback, partially operation, all those are drawbacks of denormalization because an unnormalized relation may always introduce the inconsistency. Efficiency is a very important factor in any system development. But before that, that factor that is accuracy, the consistency. You cannot say that on the cost of consistency, you introduce the efficiency. No, it is useless. If the system is not working well, what happens if it is efficient? That is why always keep this thing in your mind that your system should work well. After that it should be as efficient as possible. That is why denormalization is a possibility in which you have seen three situations. And you should see in which case you should denormalize. Do not say that in every case you are going for the denormalization. No, analyze the situation. Let us move on. Partitioning. Partitioning can also be thought of as a form of denormalization. But what you used to do was that you used to merge the tables. Here it will be that you will divide the same table and partition it. See what happens in this? Denormalization leads to merging different relations whereas partitioning splits same relations into two. In this, that factor that duplication is taking place will not happen. But in this table when it breaks, we will see the reasons why two types are possible. Horizontal partitioning and vertical partitioning. First of all, what is partitioning? Partition means you can call it in simple words parts. Parts. You divide one table from one to two or more than two tables. You divide one table from one to more than two parts. First if we had one table, it would be two or three or whatever you want to partition it. Partitioning is that you divide the same table into different tables. There are two possibilities for this. Horizontal and vertical. Horizontal means you are doing it row wise and vertical means column wise. Table is split on the basis of rows. If you have a table on the basis of rows, you have to make a record of one lakh. If you make a partition of one lakh, you have to make a partition of 30,000 to 30,000. If you make two, you have to make a partition of 50,000 to 50,000. You don't have to make a partition of 40,000 to 60,000. Horizontal partitioning brings efficiency. It brings efficiency and it takes less time to process a large table to process a small table as compared to a large table. To process a small table, you have to do any operation, you have to join, you have to do any selection, you have to do any searching. There will be less time as compared to a large table. The second thing is that you have to see if partitioning is possible and you have to make a general rule that a small table that matters both the size and the width and the width that matters both the size. A general rule is that processing a small table and doing some searching is efficient because it is a general rule. After that, every partitioning has further requirements. On its basis, you will decide which type you should partition. The idea is that it is more efficient to process a table with a smaller number of rows than a large table. It also helps in the maintenance of tables like security, authorization, and backup. Security is that if you want we have to give some tables access and some on the other table. So, in this way you have to first say that we have 1 lakh records. Some of them we have users who just have to first say that we have to give them access rather than placing them all in the same table you have to multiply them and give them access to that partition where you have to record the other group by placing the other partition you have to give them access. Security wise, another thing is in case of failure if you have a large table if you have a flop or damage you get a bigger loss.  If you look at authorization if you talk about the user access partition wise it will be easier to manage their authorization. Then this is about backup you can also take the backups I will read the backups in detail later so you can take the backups more efficiently even can be placed on different disks to reduce disk contention as I said we have to first we have 1 lac record and at the same time we have to first access 15 users simultaneously this means 15 different users are trying to access the same disk so the response time or the utility of the disk increases so the rush on the disk the contention situation to reduce it you can also do that you create the partitions and place different partitions on different disks the curiosity of the users instead of going on the same disk nor they can be divided on to different disks this can also benefit the partition the horizontal partitioning can be on different types here I am mentioning some general types partitions and this varies depends on whether it is dbms or dbms it is possible that if you have a tool that varies but this is general which is generally found in dbms on the other hand there is a range partitioning this is straight forward you can also fix the range the range is you place a check you place a condition on the value of some attribute because the horizontal partitioning will always be row wise horizontal partitioning means row wise you will divide the rows of a table in different partitions the range partitioning means whatever data you have you place a check on any attribute and generally you implement this check or there can be other ways but you place a condition that the value of this attribute the value of this range will come in this partition the value of this range will come in this partition you have to define two partitions you have to do three or four partitions so it is totally up to you the advantage of that when you give the range partition the different rows that you have in different partitions the partition of individual table has reduced but at the same time if you want a query that spans over the entire table you have a query so most of the applications will say these 30,000 will run on this 30,000 to 40,000 so for that you partitioned them but there is a query that spans upon all these rows it runs on 1,000,000 records so there is no problem whenever you want in such a situation you can view them as a single table the idea is to create a table and also define its partition and if the partition is based on the range then the range will be defined now when you will apply a query on the table when you give the table it will automatically join and it will run on the entire partition but when you want to apply a query and an application and a particular partition just name it so this is called range partition this can be an example for example if you talk about student ID you say that the students whose ID is from 1 to 1,000 they come to partition 1 whose is from 1,000 and from 2,000 they come to partition 2 and first they come to partition 3 if your student ID ranges from 1,000 to 3,000 so in this way you will create 3 partitions so DBMS automatically will identify that this is the key value which you have determined based on that the DBMS will automatically place it into the appropriate partition another example of this can be age you can say that the people in the age group of let's say 15 to 20 they are in one partition people from 21 to 25 and like that the range partition whenever you enter the record you do not need to worry in which partition it is going you simply enter the values the DBMS will automatically place it into the appropriate partition and if you want to do it on all simply the table on it it will automatically span on all the partitions dear students I hope you have cleared the range partition in the range partition the problem whose chances are that your partitions they may become unbalanced if you do not have control that what is your data enter from what nature from what style then you may have a problem that your one partition is heavily loaded there are a lot of records and there are few for example if you say that we have an employer range from 1 to 30,000 partition 1 from 30,000 to 60,000 partition 2 and 60,000 on and 1,000,000 in partition 3 you may have from 30,000 to 60,000 in that there are 25,000 records that you have entered so many records there were 2 records because you have no control on the input of data which flow is entering the flow has become in that partition there are many but the other partitions from 1 to 30,000 it may be 2,000 and the next one from 60,000 to 1,000 it may be less so this is a possible problem with this range partition is that it may make, it may turn the partitions unbalanced so it will not give you overall efficiency because the applications you are are heavily loaded on the partition will slow down and the ones with less records you will get the answer quickly so this is the drawback and again you have come to know what are the advantages but also what is the drawback now see what are the other types of partition there is another type of horizontal partition in this you have the drawback of the range partition that your partitions can be unbalanced in terms of volume in terms of load to balance it we have a hash partition you might have studied about it in the data structures but if you do not read the hash the idea is that you have an attribute on a value that you apply an algorithm some programs apply an algorithm from that algorithm you get a value randomly based on that you make a different decision you place things you identify them the idea of hash partition is that rather than defining a range in this range in this partition what you do is you do hash partition what you do is you define an attribute that you identify a particular field that you will partition it but when partitioning is a type that is not the range partitioning rather it is hash partitioning and dbms itself now you do not know you do not need to know what is the hashing algorithm how does this hash apply in dbms you do not need to know simply you have this attribute you partition it and hash partition dbms will apply an algorithm and based on that algorithm dbms will decide which partition should go during this placement when dbms is placing the record the different partition the dbms is also taking care of the balance of the partitions your partitions will not have much unbalance they will have almost the same number of record mind it do not think that they are placing one by one or they will always be exactly balanced like 15, 20, 30, 40, 100 there will be a huge difference but there is not much difference in efficiency as much as you have range partitioning that is 25,000 and 1,000 now this is too much difference so your hash partitioning there is no such difference there will be no such difference rather it will keep it balanced and you will get an advantage your performance different partitions will be almost balanced it will not be unbalanced like there is possibility in range partitioning third is list partitioning list partitioning is that you to specify the range of hash use specify certain values that this attribute that this value comes in this partition in this specifically for every partition specify certain values that these values come in this partition list partitioning in this as you see as you can define a range then you cannot give range you do not need to give range on the other hand you talk about color you say if we talk about vehicles we talk about car colors we say red and black they come in this partition in which vehicles are doing vehicle color we have a category vehicle color red and black partition 1 and if it is white and gray partition 2 first if it is blue partition 3 in this you have specified a list for every partition that is called the list partitioning now we had 3 types of partitioning and some dbms their different combinations they also support when you use particular tool then you will see which type of partition they support but again this is now your job that you have decided the first question is that we should not partition so that is the situation when the table size is too large and when it is slow on different application and you have a possibility that you can divide it horizontally if you can place different partitions then you will say you should partition further decision can be made if I can I can place different partitions on different disk then it will control the disk convention so the first thing you have to see I should not partition this is the first question after that you have got different partition types that as we have seen range or hash list or any combination then you have to see how is the data flow how is it coming then you will decide if you know that the data is evenly distributed then you can go and plus you have got a form of range you can specify the range based on that the flow and data is even then you can arrange it but as we have discussed that you cannot give range then you have got the hash possibility and also you have got the list possibility to specify a range in case of individual values then you can see that these are all decisions and this is the efficiency of your ultimate data process so this is the decision you have to make as a developer as a designer Dear students in today's lecture we are discussing physical data based design one is denomalization and other is horizontal partitioning in denomalization you have seen the normalized relations that you got after denomalization you denomalize them or split them although the accurate approach is that they should be normalized but for efficiency purposes we have merged them and the second thing is partitioning partitioning means that you split the same table horizontally and the vertical partitioning we will see in the next lecture but the last thing is that all these are different options and you have to select whether you should do this or not that is all thank you for watching see you next time bye


V zelo se je zelo skupnjeni objezovati, da je to zelo skupnjeni objezovati. V Markovoj izgleda je objezovati, da je to zelo skupnjeni objezovati. S tem, da je to zelo skupnjeni objezovati. In je to zelo, da vzgledajte, da se je ovo početno skupnno, vzgledajte na vzgledajte, in do gvrstvenosti, vzgledajte vzgledajte, a zelo vzgledajte, in da se je zelo vzgledajte. da bomo se pošličiti na učenju za vzvečenjem tudi, in se vidimo na tukaj. Mamo na pomečnje, da je zelo tudi zvačenje. In vzvečenje je, da se vzvečenje je svačenje. Ovanč dominancele su utvojo. Kaj psih in glibaj savesboardi, k 그런데 t adore. Masih t smo vličinati, ta sebrina pri applianceskih upfront zelo o n BENE za tvojee in debtski spivil. zgodno. But usually we have someone that decides that it is the time to switch to something else for the same custom, and one answer is in the office. So looking at the protocol, usually they start from here where I am learning on the final pattern. Zato, da se pričeš, da se najbolj načinjamo, da se najbolj načinjamo na kratk, da je vse delo, ker je načinjamo, da se pričeš, da se pričeš, da se pričeš, da se pričeš, ...in kako se jaz način igreš. ...a to je danes problega.  Srednji jaz se odi načilo, da je začela inest, da se daje zelo načo, bo načo v Izraelu to je testov in panto, da je zelo veliko načo. In je zelo malo dificil zelo, da so vse sveto srečno in očilo. to je dodaprej dano zredn gentleov, poločne zrednje. Tako, nekaj mi ovo tudi razližočenih, je to sranjsko izjavljena v nekaj pajor, je to zelo tudi podobne, shovebo nekaj imo v pajor. Vse možete, da možete izgledati v svoj počke, zato ne musete izgledati z vsej pizdi, in boš izgledati svoj počke, da se predajte. Vse možete izgledati, da se predajte, da se predajte, da se predajte, da se predajte, da se predajte, da se predajte. tako. The step is exactly the same, but it's important to also to use the proper name for a step. Going back to the deployment, to the technical part, it's possible to deploy on the graph, it's a good idea to be able to use it, Zvukam o konfiguracijenju do vsehoj polizije, zato, da je tudi prišljala, da vsehoj vsehoj vsehoj vsehoj vsehoj vsehoj vsehoj vsehoj vsehoj. izgleda in vse. Zgleda, nekako je tudi izgleda, zelo to je nekaj, in ta je bila najbolj, nekaj nekaj nečo, nekaj nečo, nekaj nečo, nekaj nečo, nekaj nečo, nekaj nečo, nekaj nečo, tk. na konfiguraciji, tako da poživajte v tega inibrafizu. Zdajte, da, s premonizacijem, da poživajte v tega inibrafizu, da je tako, da jazem v tega inibrafizu in prihledaš menev, začačaš naši cašnih informacijih, začalš po vzivnih vziv, kjer se preddajila vzivno, in došla v žeši patrički, z vzivnimi vzivnih naši vzivnih naši, In Jale Van was from Nauha. The good policy objective are really simple. I don't know if you already have seen a good policy objective. We are talking about two fights. One, all the fights are in XML. We have one fight that is the destruction of your policy. And the other one is for the language. So it's not complex to create this fight. You need to know which are the key that you need to add in file. But in Jale, we already have all these key, even in our advanced configuration in the library. If you try to have a look under the tools options in the library. There is a nice button. I can show you a little bit of the screen. Sorry for the confusion. We have to do this in the program. It would be nice if we have an advanced configuration. Here you can find all the key that is available in the library. Some keys are the same that you can find when you try to configure the library manually. So you decide that your default font is which one, et cetera. But from this menu you can also find the other configuration that is available from the user interface. The advantage of this massive configuration is that everything that you define on the interface. And what you define, the other policy is located for the user. So if you decide that the user can see a particular menu, the user can access that menu. The button could be there, but it's gray and it's disabled. So in general, with group policy, you can avoid that the user, for example, try to change the user interface, or try to modify a particular option that we decided to add. From the technical side, when you try to administrate something via policy, you have something like this one, and the different options are classified in the folder. So everything you see is a folder, and on the right side you can see the detail of this policy. So in the first version, and also the other one, in reality there are two main issues. The first one is that you have a list of possible options that the technical support should enable. And from my experience, it's better to have only the option that can be needed by finding this particular list via the optimization that we want to migrate. The other issue is that not only the option, but if the IT software is not so involved in the project, and maybe the risk is that there are some options that are completely unknown. And sometimes the other risk is that you could have some options that are not useful for the last version that you are employing. So instead of having this bigger number of configurations available, the idea is to create a set of policies that are modular. This approach is very valuable in the policy. It is not needed to change the installation, or to modify your Windows set for example in this modern way. What is changing is the way to write the policy. So it has that very public administration in general. Every entity that decided to migrate during the assessment phase decided which are the integrations that should be blocked on the GPU side. And after this assessment, the IT software will visit only the module that are needed. So the list of configurations that the IT software needs to modify are really short, and it is simple to manage the configuration and the evolution of this massive deployment. The other idea is to create extensions in particular to areas that are useful for every massive deployment. In particular, the extension is useful because for the public administration, there are a lot of extensions that are useful or require the government that needs to provide. So instead of finding every time the same test or start to be based on the required test in the government, the idea is to collect everything and then create the extensions that are up to the deployment of the test and then also the way that are useful for the innovations. So this one is less known what is the feedback from the Italian center for the massive deployment and migration to the graphics. We are going to question, and then we are going to answer the questions that the IT software needs to provide. So we are going to question what is the feedback from the IT software and what is the feedback from the IT software. So we are going to question


Hey everyone, welcome again to Higan Iruthil. We have a new announcement. This was actually announced yesterday, didn't have the time to Give this to you guys, but there is a limited beta Confirmed. So dear directors, it's time to meet again on planet Iruthil, but this beta Testing will only be in Singapore and Malaysia So take note for my Kababayans or for my fellow Filipinos who are eager to join this one I might say that probably we can't join this but again do comment in the comment section of this post Hopefully we can have more you know petitions for the Philippines to join and other Asian countries as well The players are actually excited to have this one, you know launch Again, hopefully by January, but again this one this December 1 to 14 would be would probably give them again a taste of What is to expect and probably excite them more? So again guys, if you are listening to me the devs for the game Please also open this up to other countries I know that would be a big scope for the for the beta test, but again It would also mean a lot to you know as public relations to your fans already The Asian community probably open it up to I don't know all of Asia or probably global because you already had a global beta test a while ago, but again guys Hopefully you can open this up to a lot of people to join Me myself, I'd like to be in it if you can you know, give me a chance. I would really you know do a lot more Content and probably have more reviews of the game even before launch I'm really itching to get my hands on this game and play this game So hopefully you guys if if you know if it's going to be Singapore and Malaysia Hope you guys that are there. Hope you can join this watch out for this This will be announced Probably real soon because it's already the 27th right now Definitely, they are going to give additional announcement on this either on the 28th 29th or the 30th So, please be sure if you're in Singapore and Malaysia Make sure that you watch out for this and there you go guys and I will see you in the next one


The NSA is spying and was spying and we had Snowden, we have a lot of documents to look at and there is some new research on how they used geolocation methods in mobile networks. It is done by the University of Hamburg and we have here Eric who will present this research to you and he has done this for the German government for the NSA Untersuchungsausschuss which we call NS-Auer which means like NS-Auch kind of. He is a PhD student and holds a master in physics so give him a warm applause and for those coming later please go to your seats and try to be quiet. Yeah, thank you. Hello, I am really happy to have you all here and I welcome you to my talk about... Hello, I think it's good that you are all here, welcome to my talk. I am Alexi, Eric Sy. I am a student here at the University of Hamburg. At the beginning I would like to explain why I am holding this talk. The German parliamentarian investigative committee has set up the NSA Untersuchungsausschuss in NS-Auer to find out how they are involved in the drone war. The government says that they do not know anything or they do not know any possibility. The government says that they have no idea or do not even know how to use a phone number to make a target drone. The committee did not really believe the statement and so they asked our research group at the University of Hamburg to give a report and we handed in that report and the one after what was also published by NetsPolitik.org, thank you for that and it contains technical methods and approximates the accuracy to localize the phone and it also points out which technical identifiers are required to do something like that. Now I give you my agenda for today. First of all, I would like to talk about the purpose of geolocation data and the reason why you need geolocation data, then different possibilities, how you can find someone via geolocations, then specifically about the methods with the drones and then I will talk about which technical identifiers we have for mobile network. And then I will make another summary. It is geolocation data is a technology that we can use to find everyone, for example who lives in the forest or who has already used Google traffic. They use it, for example, to monitor the traffic situation. But we can also use the privacy of a person who uses it to listen out. For example, if we observe an individual for a longer period of time and of course also to carry out targeted drone attacks, but I would like to point out that these data are not suitable to determine a person individually. If you make a drone attack based on this data, you are not sure who you are actually turning around. On the right side you can see a picture of such a crater that has caused a hellfire rocket. You can estimate that the explosion radius is about 120 meters. A targeted drone attack we would estimate something more precise than 20 meters. So the first, the first voguing that I want to show are time measurements. What you see here is a base station used to connect mobile phones with the network. You can see it from a fake station to log on to mobile phones. The method used to find a mobile phone is the triangulation of different masses. A signal moves mostly with the speed, the light speed. So if you have the difference of the different signals that come, you can estimate where the phone is. The accuracy for such a measurement is between 50 and 200 meters. It depends on the size of the cell. So then we have time difference like a round trip measurement. Then we have the difference of the time of the time difference and we have the improved observed time difference and the accuracy is between 50 and 125 meters. So the next method which I want to show you is angular measurements. If you want to determine the direction of arrival, then I would say you do a calculation which is called a triangulation of the position of the two base stations and also the direction of the antenna. The accuracy is approximately 100 to 200 meters from experiments and the difficulty of this method and the last sheet is that you don't always have a contact with the mobile phone to the base station. So the signal is destroyed and destroyed by buildings in between and the accuracy suffers from it.  GPS satellites broadcast their position and the actual time and the mobile phone triangulates these data to determine their own position. The accuracy varies, but that depends on the chipset of the mobile phone. The base station can then ask the mobile phone for the radio resource location service protocol. A further method to take over are, for example, the mobile phone networks, the SSID data that you have on your phone. These allow the accuracy of the position of less than 10 meters. It is definitely possible to cut this communication in order to determine the position of a person. Here in the first example, each of the Google Maps is used on a mobile phone. And that's 2008 from the Snowden archives. So there we see at least that it was possible at that time, we have evidence for that. There you can see that people used it to recognize the position of people. And if you want to determine the location with the SSID, it is necessary that you have a card on which it is shown where different Wi-Fi access points are positioned for example. And for that, we also have a proof that it was done by the NSA, that was the Mission Victory Dance, where they used the Wi-Fi fingerprint, that was in Yemen, where they did relatively a lot of drone shots. That was the next method. Signal system number seven is a protocol that is used to communicate between network providers. And network providers need to know in which cell a mobile phone is to enable the communication. The position of the mobile phone is saved in a local register and third parties, other people can ask this position. Here I refer to a lecture by Tobias Engel, who has been holding it for two years, who goes into detail on this method. And if you want, you can also ask commercial providers to ask this data. Now let's talk about drones. We have very good evidence that the geolocation position recognition of drones is made. A proof for that is the Gilgamesh system. This is a method for active geolocation recognition on the Predator drones, which a MCCatcher describes. If one of you has more documents for something like that, it would be very cool to be able to see something about it. It was a call, if you have documents, give it on. The easiest method would be to ask the GPS coordinates. You just have to exchange the base location with the drone. And the method that is better, or where I think it is preferred, is the angular measurement. If our foreman looks at our report, you can see that we find the accuracy of this method and that it is between 5 and 35 meters from a height of 2 kilometers distance. And if you get closer to the mobile phone, it becomes even more accurate. It would be enough for a certain degree to make targeted drones a crime in the meantime. So while this report was handed over to the Bundestag, I have found other works that speak with a accuracy of 1 meter to 3 kilometer height. You have to know that these sensors to recognize the angle of the phone when the bigger plane becomes lighter to recognize the position. I also want to show that a single measurement can be sufficient to determine the position of the phone if we can assume that the phone is located on the ground. For example, if the phone is located in a building in Yemen, a measurement would be sufficient. So a low building in a high house would not be so good. The big advantage of this method is that nature has little influence. For example, if you don't see things. Now I'm going to talk about the identification and how the identifiers can be used to recognize the position. Every base station or IMSI location can send a request to the position and then get an IMSI or EMI back. An IMSI is like a unique description for a customer in a mobile phone network. And the EMI is a unique serial number for a device. If we include these methods in the Internet Traffic Minds, we can add a lot more identifiers. For example, an Apple ID or Google ID, a MAC address, cookies or user names. I'm really interested in that. Could you follow this link to the photo? There's a lot of interesting stuff about it. I'm coming to my last photo, to my summary. There are many different methods to determine the position of a mobile phone. I've also shown that a single drone can locate a mobile phone with a precision of a target drone attack. You said that the precision of these methods is not accurate enough. Then I've shown that the identifier of a mobile phone, the IMSI or EMI, can be used to determine the geoposition of a mobile phone. And the last information I want to give you is that geoposition can't be used to identify which person the device actually has. That means that they are not actually sure who uses the mobile phone. They only pay attention to the signal that the mobile phone sends. And they can also transfer the wrong person. Thank you for your attention. I thank my colleagues and my family and everyone. That was very nice. Thank you. That was the first lecture today where we can answer many, many questions. Come to the microphone, number one, number two, three, four. And ask your questions. It's your only chance to get an answer from this man. No questions. There's someone. No. Yeah. Sorry. No problem. Number four. Okay, the first question from number four. Hello. Do you know why we are in London right now? We are using Google Maps here. Can you ask again? Do you know why we are located in London? Yes, when we use Google Maps, we are in London. Do you know that? The Congress is located in London. Do you know why? I'm not aware. Okay. Can you please be quiet? We can't understand the questions unless you are quiet. Sorry. Okay, so on slide 12 you showed a different method. Is this a passive method or does it require an active target? It can be passive. As long as you just turn on the phone. So it has to be active in the sense that it is connected to the network. But you don't need an INSI catcher for it or something like that. You just call it and see what happens. You look at which phone is back and then you know which phone it is. I see that we have a question over there. Can you just ask a question, please? Yes, number eight, please. Thank you for the talk. I'd like to ask you a question. Can you tell us about the connection of mobile phones that are powered without electricity? Of mobile phones that are switched off. Can you elaborate on different methods? So from the user perspective. And what is it with which they took out their batteries? The answer, the answer. So to be honest, if you switch off your phone for several months, then you are sure. That's good to know. But actually, like if you have a base station and someone switches off his phone because he just wants to talk to someone privately. But if someone else, if you meet someone and he switches off his phone, then it can be suspicious. But then it really depends on whether I always look at these data or not. Thank you. Number eight again? A question from microphone number eight. I have a short question. You described, somehow, that we are dependent on the good will from, for example, the NSA. And I would like to know if there is any way to prevent that you send this information, if you use Google Maps, for example. That is fairly difficult. That's the answer. That is very difficult. I would guess that GPS phones are a little bit better for us to prevent something like that. Yes, for example, if you set up GPS buffing, because the network cells are very large and therefore it is more difficult to position yourself in the cell. And if you emit a physical signal, then the drone will always be able to localize where the signal came from. But the drone will always be able to find out where the signal comes from if you send it. It's just physically difficult. Number one thing. I have a question about the physicality of receiving or positioning of positions in a, for example, really deep-fledged region. If that is done by a drone that is 3 kilometers away, that would of course be more sensitive, that you have to be more sensitive about what your evaluation is. And then you have to be able to sort out better in the same time, with all the intelligence and so on. The answer. Normally, such a cell is between 200 and 3 kilometers big. That's why 3 kilometers in the height are not really high. So you assume that a drone meets a preliminary selection and only looks at a sub-frequency, because it, for example, knows which network you come from and in which cell you are. It depends on the region. In the urban environment, you have to reduce the size of a cell because otherwise you get too much information. But you can also have bigger cells in remote areas. Because of the remote areas, the drones are the size of a quadcopter or the size of a plane. Do you have the classic methods to observe something for a longer time while you fly over it to integrate it into your calculation? Those are the methods with which we get our high resolution radar pictures. Yes, you can use different measurements, but you can only use one if you already know where the target is. But that's not necessarily necessary. Thank you. One question from the internet. Yes, the internet wants to know if there are attributes that you can change from your phone to stop surveillance, for example the email address. The email, not the email. Yes, of course, you can fake the email or the IMSI. That's another reason why the mobile alone is not enough to prove who the person is. Another question from the internet is does the GSM network have a feature that allows everyone to ask the GPS data from a mobile phone? Yes, it would also be the Radio Resource Location Service protocol. The Radio Resource Location Service protocol is the answer. Thank you. Hello. You never, you worked to the NSA investigation office? They had an NSA investigation office and the Bundestag didn't say anything about it. Is there a statement from the NSA investigation office? Yes, the government said that. They said that they washed their hands clean. We did everything nice and nice because we added a disclaimer to the data. And then the disclaimer says that the NSA has to stick to the German law and then also to make sure that they stick to the German law and therefore the data cannot be misused. Another question from microphone 6. Hello. You specified that the accuracy is about 5 meters with two drones. How would it be if you used more than 10 drones? I think it's a misunderstanding. One drone is long enough. Okay, then you could use more than one drone? Yes, you can use as much as you want. Yes, of course. But do you improve the accuracy? Yes, if you go closer, then yes. But with the same distance, but with more drones? No, actually not. Another question. I'm talking about the accuracy. You went into experiments. Have you conducted these experiments yourself? Answer. Number two, please. Yes, here's a list of things in the references where it says. My question is about the fingerprinting of the mobile. For example, in the app, which requires the fingerprinting at any time that your app, for example, asks for the fingerprinting, is this to identify the person, whether they can connect it. Yes, but I think it depends on the GSM network and the other one is dependent on the operating system. Okay, so with the current technology, is it not possible to connect it? No. So my question is about the civil use of such data. You always say geodata. They are from Wi-Fi networks and so on. And you say, yes, that you use the database from Google or something like that. There was a lecture here in 2009. Back then, it was called Skyhook. And the speaker had this provocative question, should this Wi-Fi map not be public domain, be accessible to everyone and not only belong to Apple or Google as a proprietary system. So we have, so to speak, lost this gap. So we gave our first IDs to the public domain and they shouldn't be public domain because of that. Yes, should you be able to help people in emergency situations? I would like to say thanks for the lecture and the people who have the report. It was very helpful for us because I am an expert and the people from the secret services just don't give us any information. And we need it. So for the information for you, that was one of the session members there. Okay, thanks. The talk is over. This is from the office.