Propagation Effects Handbook for Satellite Systems - DESCANSO ...

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(typically below 3 to 5 dB at 11.7 GHz). This effect is believed to contribute to the poor correlation between the excess attenuation and the cross-polarization discrimination at these low values of attenuation. In Austin, TX (Vogel-1978, 1979) ice depolarization was associated with either thunderstorms during the summer months or with clouds in the presence of polar air masses during the winter. An example of the percentage of time that XPD was less than or equal to the abscissa given that the excess attenuation was less than or equal to 1 dB is shown for the 18 month period from 12 June 1976 to 31 January 1978 and the period February 1978 to January 1979 in Figure 6.6-5. This curve shows that during 1976-78 45 per cent of the time that the XPD was less than or equal to 35 dB, there was less than 1 dB of attenuation; 24 per cent of the time that the XPD =30dBtheA= 1 dB and 12 per cent of the time that XPD = 25 dB the A ; 1 dB. In contrast, using the rain depolarization relation for 1 dB yields XPD = 40 dB. Therefore systems requiring 30 dB or more XPD should expect a significant number of depolarization events due to ice. Also, it has been observed (Shutie, et al-1978) that at 30 GHz ice crystals yield a constant value (typically 90 degrees) of the relative phase angle between the crosspolar and copolar signals as a function of XPD as shown in Figure 6.6-6. The corresponding polar plot for a heavy rain event is shown in Figure 6.6-7. In this case the XPD was reduced by signal attenuation and the signal to noise ratio of the relative phase measurement decreased as the XPD decreased. This effect appears to increase the scatter of the phase angle with decrease in XPD. English investigators have also noted that rapid changes in relative phase and XPD are observed in thunderstorms and are associated with realignment of the ice crystal orientation by the electrostatic fields. In electrically-active storms~ these 6-116 ‘
-. 50 40 30 20 10 0 . T(XPD < ABCISSA I A < ldB) T(XPD < ABCISSA) x 100 12JUN1976- 31 JAN 1978 0 FEB 1078- JAN 1979 10 15 20 25 30 35 CROSS POLARIZATION DISCRIMINATION – dB Figure 6.6-5. Contribution of Ice Depolarization to all Depolarization Events 6-117
Page 1 and 2:
1 6.1 INTRODUCTION 6.1.1 purpose CH
Page 3 and 4:
,s Table 6.1-1. Guide to Sample Cal
Page 5 and 6:
I . . 6.1.4 Other Propagation Effec
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. . collisions at normal atmospheri
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D 1000 100 10 1 U.S. Standard Atmos
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Frequency (GHz) 10 15 20 30 40 80 1
Page 13 and 14:
If PW is not available from local w
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. . The equivalent heights for oxyg
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m t TEMPERATURE rC) o 5 10 15 20 25
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6.3 PREDICTION OF CUMULATIVE STATIS
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LSTATION LOCATION AND ELEVATION STE
Page 23 and 24:
The models require the following in
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I z za E 100 g w ~ z z K 50 a) ALL
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B . . . t- I I I I I 1 11/1 - . . .
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.- . 9 s@EQ - If Z S D, compute the
Page 31 and 32:
1 0.02 0.05 0.2 0.5 4. Compute D: U
Page 33 and 34:
I . ,. . ~ q 8 H v ~ 1.0 0.8 0.6 0.
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Step 6 Calculate the attenuation ex
Page 37 and 38:
m I : STEP 1 SELECT CLIMATE ZONE FR
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9 10.OOOO 1.0000 0,1ooo 0.0100 0.00
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1 6.3.3 Estimates of Attenuation Gi
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● We now proceed exactly as in th
Page 45 and 46:
STEP 1 GIVEN: STATION PARAMETERS SA
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. B . . . 4. Repeat the process for
Page 49 and 50:
. . ● 100 10 1.0 .1 .01 . . RAIN
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not normally available~ but empiric
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● The intensity-duration-frequenc
Page 55 and 56:
- GIVEN: STATION PARAMETERS OPERATI
Page 57 and 58:
m I s 70 2(J I 10 0 a) BY SEASONS
Page 59 and 60:
.“ ● change in rain rater the r
Page 61 and 62:
m To x o 6 x(n wux!- (5 zawwvxw x 1
Page 63 and 64:
● ✎ ✎ ✎ 10 1 0.1 0.01 0 . -
Page 65 and 66: ● ✎ ✎ ✎ appears to be gener
Page 67 and 68: 6.4.2.3 Statistics of Microwave Eff
Page 69 and 70: ● For each hour’s observations,
Page 71 and 72: Plots of noise temperature and atte
Page 73 and 74: .- I where Lf is the fog extent~ in
Page 75 and 76: than a minute and on spatial scales
Page 77 and 78: . . . 022 = angle-of-arrival varian
Page 79 and 80: B . . Figure 6.5-2 represents the a
Page 81 and 82: - . . , 1 I t , 3 , I 1 # 1 1 aJ 0a
Page 83 and 84: I . . -. % i ! ~ * 76.00 I h 60.00
Page 85 and 86: I where the constants are the same
Page 87 and 88: .U . . \ Table 6.5-1. Fading Data P
Page 89 and 90: o -5C \ A — . \ \ \ \ N- ● ●
Page 91 and 92: I 1 \ 0,, FADE DEPTHS I 1 l.d 0.1 1
Page 93 and 94: 9 m ELEVATION ANGLE [DEGREESI ELEVA
Page 95 and 96: Figure 6.5-12 is an example for thi
Page 97 and 98: equal. The fade distributions resul
Page 99 and 100: m . ANTENNA BEAMVVID~ (DEG) d o 0 w
Page 101 and 102: . . 6.5.5.2.2 Spatial Diversity. Pa
Page 103 and 104: fluctuation power at 1 Hz is on the
Page 105 and 106: develops (Pruppacher and Pitter-197
Page 107 and 108: .8 where: f = frequency, in GHz r =
Page 109 and 110: B . k 11.7 26 \ QHz DATA, CTS A VPl
Page 111 and 112: \ for the 11.7 GHz CTS beacon at 50
Page 113 and 114: ● these do not correlate well wit
Page 115: . However the XPD dependence on ele
Page 119 and 120: 9 electrostatic fields discharge ra
Page 121 and 122: , f w m I
Page 123 and 124: . XPD 2 = XPD1 - 20 lo91~ f ~ 1 0.4
Page 125 and 126: ● 3.0 14 0.6 0.3 0,1 0.0s 0.03 0.
Page 127 and 128: where, for example, for the frequen
Page 129 and 130: L .- . ., not appear to be sufficie
Page 131 and 132: D ‘1 may be considered to be rece
Page 133 and 134: D - 0 m a 80 60 40 20 0 -20 \ — i
Page 135 and 136: m I s 1 \\ I , t Frequency (GHz) Fi
Page 137 and 138: -. Table 6.8-1. Cumulative Statisti
Page 139 and 140: D - The propagation margin is then
Page 141 and 142: 1- * w -180 -190 -m -21 / ---+---4~
Page 143 and 144: - . . 6.9 UPLINK NOISE IN SATELLITE
Page 145 and 146: 280 260 240 220 200 180 160 140 120
Page 147 and 148: 6.10 REFERENCES Ahmed, I.Y. and L.J
Page 149 and 150: ● International Telecommunication
Page 151 and 152: Atmospheric Emission observations,
Page 153 and 154: 8.6 and 3.2 mm Radio Waves by Cloud
Page 155 and 156: I Strickland, J.I. (1974), “Radar
Page 157: D Wulfsberg, K.N. (1964), “Appare
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