 Hello everyone. Welcome to the session. I am Mr Praveen Alapakumbar. Today we want to see system design examples. The learning outcome of this topic is, at the end of the session, students will be able to explain the concept of system design in satellite communication. The contents of this topic are first introduction, second system design example. The following system designs demonstrate the ideas can be applied to the design of satellite communication system. This table shows KU band satellite parameters. For design of a satellite, we require KU band parameters. Whenever we design a satellite, we require uplink as well as downlink parameters. This is a transmitting KU band R station. This table shows the different parameters and their values. This table shows receiving KU band R station. This different parameters and their values are as follows. For designing of a satellite system, we require rain attenuation and propagation factors. And the different rain attenuation and the propagation factors for the uplink as well as for the downlink, their different parameters are shown in this table. Now we want to see system design example. Question. The design of a satellite communication link using a KU band geostationary satellite with band pipe transponder to distribute digital KV signals from an R station to many receiving stations throughout the United States. Now when you read this question, here we want to design a satellite communication link in the KU band in the US. Now we want to design the system. For design of the system, there are two steps we require. The first step is KU band uplink design and KU band downlink design. Now we see one by one KU band uplink design as well as KU band downlink design. First, KU band uplink design. For this KU band uplink design, we require design of uplink noise power budget, the antenna gain, the free space path loss, uplink power budget. For the KU band uplink design, when you calculate all these four things, then the uplink design is done. Uplink noise power budget. Everyone here pause the video and recall the noise power formula. The transponder noise power is equal to N, that's formula is N is equal to K plus TS plus B, that is equation number one, where K is a Boltzmann constant and that's value is minus 228.6, that's unit is dBVat per Kelvin per hertz. Where TS is the receiver system noise temperature, that's value is 500 Kelvin, that is the Kelvin is converted into the dB Kelvin and after the conversion of this 500 Kelvin into the dB Kelvin we get 27 dB Kelvin. B is the receiver IF noise bandwidth, that's value is 43.2 MHz that convert that MHz into the dBHz after the conversion of this MHz into the dBHz we get 76.4 dBHz. Now put these values into the equation number one, we get transponder noise power is equal to minus 125.2 dBVat. But whenever we receive the power at the transponder input that must be greater than the 30 dB than the noise power. Therefore we add this 30 dB into the equation number two, we get transponder noise power as minus 125.2 plus 30 is equal to minus 95.2 dBVat. Now we want to design the antenna gain, for that antenna gain the formula for the antenna gain is gt is equal to 10 log 0.68 into pi d by lambda bracket square. This is the equation number three, where d is the uplink antenna diameter that's value here for the design of this antenna gain we take here 5 meter. The wavelength is equal to lambda is equal to 2.120 centimeter, but now for when we design this antenna gain we convert this centimeter into the meter after conversion of this centimeter into the meter we get 0.0212 meter. Now put this value into the equation number three, we get the antenna gain is 55.7 dB. Now see the free space path loss that is Lp. Now the formula for that free space path loss Lp is equal to 10 log 4 pi r by lambda bracket square that is equation number four. After the putting the value of r and lambda we get Lp is equal to 207.2 dB. Now d, uplink power budget. The formula for the uplink power that is Pt is equal to gt plus gr plus Lp plus lant plus lm that is equation number five. Before solving this one we want to understand what is the meaning of the each term and what is the value of the each term. Now first that is a Pt that is a r station transmitted power that we want to calculate here. Gt is the r station antenna gain that is 55.7 dB. Gr is equal to satellite antenna gain that is 31 dB. Lp is the free space path loss that is minus 207.2 dB. Lant is equal to e by s on 2 dB contour that is minus 2 dB. Lm is the other losses that is value is minus 1 dB. After putting all these values into the equation number five we calculate r station transmitted power that is Pt is equal to minus 123.5 dB band. Now we want to design KU band downlink design. For the KU band downlink design we want to solve the first calculate the downlink that is c by n downlink. Second calculate the required received power. Third calculate the path loss. Now we want to calculate first calculate the downlink that is c by n downlink. Before the calculation of a downlink we know the formula 1 by c by n down is equal to 1 by c by n 0 minus 1 by c by n up. Where c by n 0 is overall c by n ratio that is 17 dB. After the conversion of dB into the normalized function we get that is value is 50. c by n up is equal to 30 dB. To convert this decibel into the normalized function after conversion of this dB into the normalized function we get 1000. Put this value into the equation number six we get 1 by cn down is equal to 1 by 50 minus 1 by 1000 is equal to 0.019. That is 1 by cn down. Now cn down calculated by 1 upon 0.019 that is 52.6. This normalized we again convert into the decibel after the conversion of this normalized into the decibel we get 17.2 dB. Now we want to calculate required received power. For that the formula is pr is equal to n plus 17.2 dB that is equation number seven. But before the calculation of this received power we want to calculate the first n. Where n is a transponder noise power and pr is the power at earth station receiver input. Now the before calculation of that one we want to calculate first n. The n is equal to k plus ts plus bn where k is a Boltzmann constant that's value is minus 228.6 dB per Kelvin per hertz. Ts is equal to 140 Kelvin after the conversion of this Kelvin into the decibel we get 21.5 dB Kelvin. Bn is a Boltzmann constant here 43.2 MHz the conversion of this MHz into the decibel hertz we get 76.4 dB. Now putting this value into the equation number eight we get n is equal to minus 130.7 dB. Therefore the received power pr is equal to n plus 17.2 dB. After the putting the value of n into the above equation we get pr that is received power is equal to minus 113.5 dB. Now we calculate the path loss. For the calculation of a path loss at 11.45 GHz the before the calculation of a path loss is this for this frequency. We know the first frequency is at the 14.15 GHz at that frequency path loss was 207.2 dB. From this frequency we can calculate the path loss at this frequency. For the calculation of for that frequency at 11.45 GHz path loss is Lp is equal to 207.2 minus 20 log base to the 10 14.15 divided by 11.45. That after the calculation of this thing we get path loss equal to 205.4 dB. Now downlink power budget the transponder is operated with 1 dB output back off. So therefore Pt is equal to 19 dB back minus 1 dB is equal to 18 dB back that is a downlink power. And the received power pr is equal to Pt plus Gt plus Gr plus Lp plus La plus Lm. Now where pr is the received power at transponder Pt is the satellite transponder output power that is 18 dB back. Gt is the satellite antenna gain that is 31 dB. Lp is the free space path loss that is minus 205.4 dB. La is the E by S on 3 dB counter of satellite antenna that is minus 3 dB. And the Lm is the other losses that is minus 0.8 dB. Therefore put this value into the above equation we get pr is equal to minus 160.2 dB. The references for this topic is thank you.