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12-4 Propagation Effects for Vehicular and Personal Mobile Satellite Systems A( P, θ , f ) = A( P, 20 ° , f ) (12-9) In Figure 12-1 is a family of cumulative fade distributions at 1.5 GHz for elevation angles ranging from 20° to 60° calculated using the above formulation. Percent of Distance the Fade > Abscissa 100 10 1 f = 1.5 GHz 60 55 50 45 40 35 30 25 < = 20° 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Fade (dB) Figure 12-1: Family of cumulative fade distribution curves derived from application of the EERS model at 1.5 GHz. 12.3.2 Effects of Foliage Systematic measurements of the effects of foliage have been made for mobile-satellite scenarios at UHF (870 MHz) and K-Band (20 GHz). The empirical relations are: At f = 870 MHz, 1% ≤ P ≤ 80% A( foliage) = 124 . ⋅ A( no foliage) (12-10) At f = 20 GHz, 1 ≤ A( no foliage) ≤ 15 dB ( 1% ≤ P ≤ 50%) A( foliage) . . [ A( no foliage)] . = 0 351+ 6 825⋅ 0 578 (12-11) where A foliage A no foliage ( ), ( ) are the equal probability values of the foliage and nonfoliage attenuations expressed in dB, respectively. The expression (12-11) is identical to
Summary of Recommendations 12-5 that of the static run except that the range of validity is different in percentage and attenuation ranges. 12.3.3 Suggestions for Future Efforts The EERS formulation has been validated at 870 MHz, 1.5 GHz, 3 GHz and 20 GHz. It is recommended that further validation be applied at 5, 10, and 15 GHz. This formulation should be further extended to frequencies in excess of 20 GHz for systems where appropriate fade margins are available. 12.4 Signal Degradation for Line-of-Sight Communications (Chapter 4) Cumulative fade distributions are presented for land-mobile satellite scenarios where multipath is the dominant cause of signal degradation. The multipath environment may be due to roadside trees, utility poles, terrain, or a nearby body of water and is generally dependent on the antenna beamwidth characteristics. 12.4.1 Empirical Multipath Model The following empirical multipath model is valid at frequencies between 870 MHz and 20 GHz and elevation angles between 8° and 60°. For 1% ≤ P ≤ 50% or 0. 6 ≤ A ≤ 4. 6 dB P = 9437 . ⋅ exp( −9863 . ⋅ A) , (12-12) where P is the percentage of the distance driven over which the attenuation A (dB) is exceeded, assuming only multipath conditions. The model distribution uncertainty is approximately within ± 1.5 dB of 12 measured distributions at equal percentages greater than 2%. Between 1% and 2%, it is within ± 3 dB. The model (12-12) includes scenarios that correspond to: (1) canyons at 870 MHz and 1.5 GHz for 30° and 45° elevations, (2) rolling hills and mountains at 1.5 GHz for elevation angles of 10° to 14°, (3) roadside tree measurements at 870 MHz and 1.5 GHz for elevation angles from 10° to 60°, (4) roadside tree measurements at 20 GHz for an elevation angle of 38°, (5) open fields and near-water at 20 GHz for elevation of 8° for which the vehicle shielded reflections from the water. The formulation (12-12) does not apply to scenarios where multipath reflections from nearby bodies of water may exist and are not filtered out by the antenna gain characteristics. Such measurements gave fades as high as 14 dB at the 1% level. Maritime multipath models described in Section 12.9 (and Chapter 9) should be used when receiving multipath reflections from a nearby body of water. Multiple type antennas were used for the above-described measurements. These included the following: (1) UHF and L-Band measurements at elevations between 30° and 60° for canyons and tree-lined road scenarios were executed using an antenna beamwidth of 60° (15° to 75° in elevation and azimuthally omni-directional). (2) Low elevation L-Band
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A2A-98-U-0-021 (APL) EERL-98-12A (E
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Table of Contents 1 Introduction __
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10 Optical Methods for Assessing Fa
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Table of Contents 1 Introduction __
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1-2 Propagation Effects for Vehicul
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Table of Contents 2 Attenuation Due
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Chapter 2 Attenuation Due to Trees:
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Attenuation Due to Trees: Static Ca
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Table of Contents 3 Attenuation Due
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Figure 3-23: Fade distributions at
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3-4 Relative Signal Level (dB) 5 0
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3-10 Percent of Distance the Fade >
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3-12 Propagation Effects for Vehicu
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3-14 3.4.3 Austin, Texas at K-Band
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3-20 Relative Signal Level (dB) 5 0
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3-24 Percentage of Distance Fade >
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3-26 and where 1 2 Propagation Effe
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3-28 Percentage of the Time Fade >
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3-32 3.7.5 Comparative Summary of M
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Chapter 4 Signal Degradation for Li
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Table of Tables Table 4-1: Summary
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4-4 Percentage of Distance Fade > A
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4-14 Percentage of Distance or Time
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Table of Contents 5 Fade and Non-Fa
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Chapter 5 Fade and Non-Fade Duratio
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Fade and Non-Fade Durations and Pha
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Table of Contents 6 Polarization, A
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Chapter 6 Polarization, Antenna Gai
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Polarization, Antenna Gain and Dive
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Table of Contents 7 Investigations
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7-6 7.3 Belgium (PROSAT Experiment)
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7-10 Probability Fade > Abscissa (%
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7-14 Percentage of Time Fade > Absc
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7-24 Probability (%) > Abscissa 100
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Chapter 8 Earth-Satellite Propagati
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Table of Figures Figure 8-1: Maximu
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Chapter 8 Earth-Satellite Propagati
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Earth-Satellite Propagation Effects
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Chapter 9 Maritime-Mobile Satellite
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Figure 9-7: Fading depth versus pat
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9-6 Roughness Parameter, u (Rad) 28
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9-8 Cθ = ( θo − 7) / 2 dB for
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9-10 Fading Depth (dB) 6 5 4 3 2 1
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9-12 Fading Depth (dB) 6 5 4 3 2 1
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9-18 Mean Fade Occurrence Interval,
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9-20 Mean Fade Duration, T D (sec)
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9-22 Fade Depth (dB) 7.0 6.5 6.0 5.
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Table of Contents 10 Optical Method
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Chapter 10 Optical Methods for Asse
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Optical Methods for Assessing Fade
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