Mission Design for the CubeSat OUFTI-1
Mission Design for the CubeSat OUFTI-1 Mission Design for the CubeSat OUFTI-1
CHAPTER 10to reach the receiver passing through the free space. The losses on this way arecalled space loss:L s [W ] =Sλ( )RIP [W ]22EIRP [W ] = 4π λ4πSd = =2 4πd( ) 2 c(10.4)4πdfwhere RIP is the Received Isotropic Power, λ the wavelength and S thepower per unit area at distance d.Passing in decibel, we have:L s [dBW ] = 20log (c) − 20log (4π) − 20log (d) − 20log (f) == 147.55 − 20log (d) − 20log (f)(10.5)The space loss contains the hypothesis of free-space propagation: in reality,the signal pass through the atmosphere and we would have therefore to take intoaccount the attenuation due to atmosphere and rain. As these attenuations areimportant only for high frequency wave (mainly in the SHF band and higher),they are practically are null in our case.Once the signal is received by the receiving antenna, its gain G R should beadded.In digital communications, the received energy-per-bit E b is equal to the receivedpower times the bit duration:E b = P R − 10log(R) (10.6)where P R = RIP + G R is the received power and R the data rate.The noise spectral density, N 0 , can be expressed as:N 0 = 10log(k) + 10log(T s) (10.7)where k = 1.38 · 10 −23 is the Boltzmann’s constant and T s the system noisetemperature.Hence, the total received noise is:where B is the bandwidth.N = N 0 + 10log(B) (10.8)Using the above mentioned equations, we can obtain the parameters we werelooking for:• the radio of received energy-per-bit to noise-densityE bN 0= EIRP + L s + G R − 10log(k) − 10log(T s) − 10log(R) (10.9)Galli Stefania 100 University of Liège
CHAPTER 10.COMMUNICATION SYSTEM• the signal-to-noise ratioSN = EIRP + L s + G R − 10log(k) − 10log(T s) − 10log(B) (10.10)This method has been applied OUFTI-1 in the most critical case: the satelliteis at the apogee and the ground station can see it at 5 ◦ elevation. Thesystem parameters are summarized in the table 10.1.Table 10.1: Communication system parametersGROUND SATELLITEPOWER P T [W] 20 0.5ANTENNA GAIN [dB] 13.4 (TX), 17.5 (RX) 0LINE LOSS [dB] -2 (TX), -1 (RX) -1.1The link budget gives the following results:Table 10.2: Link budget at 1200 Km altitude, 5 ◦ elevationDOWNLINK UPLINKEIRP [dBW] -4.1 24.4L s [dBW] -157.75 -148.26RIP [dBW] -161.8 -123.84E bN 0[dB] 20.01 43.16[dB] 19.04 42.19SNThis is en extremely simplified method to have an idea of the expectedsignal’s power at the receiving antenna. In fact, even if frequency has beenconsidered in the space losses, the dependence of some system parameter fromit has been neglected.A more detailed analysis, made by a telecommunications expert, is in figure10.2.Galli Stefania 101 University of Liège
- Page 49 and 50: CHAPTER 5.MISSION ANALYSISA four ye
- Page 51 and 52: CHAPTER 5.MISSION ANALYSISFigure 5.
- Page 53 and 54: CHAPTER 5.MISSION ANALYSISFigure 5.
- Page 55: CHAPTER 5.MISSION ANALYSISFigure 5.
- Page 58 and 59: CHAPTER 66.1 Pumpkin structureThe s
- Page 60 and 61: CHAPTER 6Figure 6.2: ISIS structure
- Page 62 and 63: CHAPTER 6Figure 6.3: P-POD: deploym
- Page 64 and 65: CHAPTER 77.1 Inertia propertiesBefo
- Page 66 and 67: CHAPTER 7I x = I x,cube + I x,M + I
- Page 68 and 69: CHAPTER 7This rough estimation is e
- Page 70 and 71: CHAPTER 7Otherwise, an orbit simula
- Page 72 and 73: CHAPTER 7only slow down the rotatio
- Page 74 and 75: CHAPTER 8order to prevent any failu
- Page 76 and 77: CHAPTER 8We have now the vector ˆN
- Page 78 and 79: CHAPTER 8Here we add an important h
- Page 80 and 81: CHAPTER 8Figure 8.5: Total power pr
- Page 82 and 83: CHAPTER 8Figure 8.8: Total power an
- Page 84 and 85: CHAPTER 88.4 Battery and operating
- Page 86 and 87: CHAPTER 99.1 Passive thermal-contro
- Page 88 and 89: CHAPTER 99.3 Nodes modelThe CubeSat
- Page 90 and 91: CHAPTER 9where c p is the material
- Page 92 and 93: CHAPTER 9We have now all the parame
- Page 94 and 95: CHAPTER 9A typical layout of a Ther
- Page 97 and 98: CHAPTER10COMMUNICATION SYSTEMThe co
- Page 99: CHAPTER 10.COMMUNICATION SYSTEMstre
- Page 103 and 104: CHAPTER 10.COMMUNICATION SYSTEMWe c
- Page 105 and 106: CHAPTER11TESTSThe launch and space
- Page 107 and 108: CHAPTER 11.TESTSof asking for some
- Page 109 and 110: CHAPTER 11.TESTSThe random vibratio
- Page 111 and 112: CHAPTER12FUTURE DEVELOPMENTSThe fea
- Page 113: CHAPTER 12.FUTURE DEVELOPMENTSspace
- Page 117 and 118: AcronymsAARACRACSADADCSASIAVUMBOLCC
- Page 119 and 120: BIBLIOGRAPHY[1] Wiley J. Larson, Ja
- Page 121: AcknowledgmentsI would like to than
CHAPTER 10.COMMUNICATION SYSTEM• <strong>the</strong> signal-to-noise ratioSN = EIRP + L s + G R − 10log(k) − 10log(T s) − 10log(B) (10.10)This method has been applied <strong>OUFTI</strong>-1 in <strong>the</strong> most critical case: <strong>the</strong> satelliteis at <strong>the</strong> apogee and <strong>the</strong> ground station can see it at 5 ◦ elevation. Thesystem parameters are summarized in <strong>the</strong> table 10.1.Table 10.1: Communication system parametersGROUND SATELLITEPOWER P T [W] 20 0.5ANTENNA GAIN [dB] 13.4 (TX), 17.5 (RX) 0LINE LOSS [dB] -2 (TX), -1 (RX) -1.1The link budget gives <strong>the</strong> following results:Table 10.2: Link budget at 1200 Km altitude, 5 ◦ elevationDOWNLINK UPLINKEIRP [dBW] -4.1 24.4L s [dBW] -157.75 -148.26RIP [dBW] -161.8 -123.84E bN 0[dB] 20.01 43.16[dB] 19.04 42.19SNThis is en extremely simplified method to have an idea of <strong>the</strong> expectedsignal’s power at <strong>the</strong> receiving antenna. In fact, even if frequency has beenconsidered in <strong>the</strong> space losses, <strong>the</strong> dependence of some system parameter fromit has been neglected.A more detailed analysis, made by a telecommunications expert, is in figure10.2.Galli Stefania 101 University of Liège