Propagation Effects Handbook for Satellite Systems - DESCANSO ...

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—“~ 232”= : ~ ERROR LIMITS /~ 5 - - 5 z 232352z ~ 10- -= ATS-6 4-SEC AVERAGE DAY 270,1974 ROSMAN, NC ~ 23’42’Z -.72 -.s4 -.38 -.18 0 +.18 +.36 +.64 +.72 GHz FREOUENCY DEVIATION FROM 20 GHz CARRIER Figure 6.7-1. Selective Fading Near 20 GHz -6 ~ -.72 -.s4 $ ERROR LIMITS TO -25 dB ERRORSINCREA8E BELOW-’6dB ATS-8 4-SECAVERAGE DAY 270,1074 ROSMAIU,NC _-uL 2“4=2 +.18 +.38 +.S4 +.72 GHZ FREOUENGYDEVIAIION FROM’”GHZCARRIER Figure 6.7-2. Selective Fading Near 30 GHz 6-128
L .- . ., not appear to be sufficiently accurate for deep fades because the signal levels approach the noise floor of the receiver. For one-minute averages~ no measurable selective fading was observed (WEC-1975). The cross-correlation of 4 and 6 GHz signals due to low angle fading in the Canadian arctic was found to be lCJW (Strickland, et al-1977) . During a 2.5 hour period on the day when the fading was most severe the correlation coefficient was 0.34 since the 6 GHz signal experienced 55% more fades than the 4 GHz signal. This would indicate significant dispersion was present, but the mechanism for this effect is tropospheric refraction and not rain. Frequency selective fading may be significant at low elevation angles. 6.7.1.2 Phase Variations. Phase measurements have not yielded significant results for frequencies above 10 GHz. The phase coherent sidetone signals on ATS-6 showed only minor variations across the 1.44 GHz bandwidths. These variations were most evident for the shorter (one and four second) averaging periods compared to the one-minute period (WEC-1975). Phase measurements have been attempted for the one degree elevation a“ngle satellites observed from the arctic (Strickland et al-1977) . Unfortunately, no significant fade events occurred and no differential phase variations were recorded. Phase effects are produced by the molecular absorption mechanism along with amplitude effects. Large values of phase dispersion would therefore be expected in the absorption bands. 6.7.2 Ionospheric Effects on Bandwidth Coherence 6.7.2.1 AmDlitude Variations. Ionospheric attenuation at microwave frequencies is inversely proportional. to the frequency squared (Flock, 1987) and is generally less than 0.001 dB at 15 GHz and an elevation angle related to cosecant 8 . 0 = 90°. The variation is approximately The attenuation is therefore usually less 6-129
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
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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
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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
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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
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1 0.02 0.05 0.2 0.5 4. Compute D: U
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I . ,. . ~ q 8 H v ~ 1.0 0.8 0.6 0.
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Step 6 Calculate the attenuation ex
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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
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STEP 1 GIVEN: STATION PARAMETERS SA
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. B . . . 4. Repeat the process for
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. . ● 100 10 1.0 .1 .01 . . RAIN
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not normally available~ but empiric
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● The intensity-duration-frequenc
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- GIVEN: STATION PARAMETERS OPERATI
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m I s 70 2(J I 10 0 a) BY SEASONS
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.“ ● change in rain rater the r
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m To x o 6 x(n wux!- (5 zawwvxw x 1
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● ✎ ✎ ✎ 10 1 0.1 0.01 0 . -
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● ✎ ✎ ✎ appears to be gener
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6.4.2.3 Statistics of Microwave Eff
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● For each hour’s observations,
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Plots of noise temperature and atte
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.- I where Lf is the fog extent~ in
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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 and 116: . However the XPD dependence on ele
Page 117 and 118: -. 50 40 30 20 10 0 . T(XPD < ABCIS
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: where, for example, for the frequen
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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