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| The '''[[ITU]] Terrain Loss Model''' is a [[radio propagation model]] that provides a method to predict the [[median]] [[path loss]] for a [[telecommunication]] link. Developed on the basis of [[diffraction]] theory, this model predicts the path loss as a function of the height of path blockage and the First [[Fresnel zone]] for the transmission link.<ref name="seybold">{{cite book|last=Seybold|first=John S.|year=2005|title=Introduction to RF propagation|publisher=John Wiley and Sons|pages=144–146}}</ref>
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| ==Applicable to / under conditions==
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| This model is applicable on any terrain.
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| This model accounts for obstructions in the middle of the telecommunication link, and therefore, is suitable to be used inside cities as well as in open fields.
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| ==Coverage==
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| Frequency: Any
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| Distance: Any
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| ==Mathematical formulation==
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| The model is mathematically formulated as:
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| : <math>A \; = \; 10 \; - \; 20 \; C_N </math>
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| : <math>C_N \; = \; \frac{h} {F_1}</math> | |
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| : <math>h \; = \; h_L \; - \; h_O</math>
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| : <math>F_1 \; = \; 17.3 \; \sqrt{\frac{d_1d_2}{fd}}</math>
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| Where,
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| : <math>A \; </math> = Additional loss (in excess of free-space loss) due to diffraction (dB)
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| : <math>C_N \; </math> = [[Normalization (statistics)|Normalized]] terrain clearance
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| : <math>h \; </math> = The height difference (negative in the case that the LOS path is completely obscured) (m)
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| : <math>h_L \;</math> = Height of the [[Line-of-sight propagation|line-of-sight]] link (m)
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| : <math>h_O \; </math> = Height of the obstruction (m)
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| : <math>F_1 \; </math> = Radius of the First Fresnel Zone (km)
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| : <math>d_1 \; </math> = Distance of obstruction from one terminal (km)
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| : <math>d_2 \;</math> = Distance of obstruction from the other terminal (km)
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| : <math>f \; </math> = Frequency of transmission (GHz)
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| : <math>d \; </math> = Distance from transmitter to receiver (km)
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| To use the model, one computes the additional loss to each path obstruction (A). These losses are summed and then added to the predicted line of sight path loss which is calculated using [[Friis transmission equation]] or a similar theoretical or empirical model.
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| ==Limitations==
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| This model is considered valid for losses over 15 dB and may be valid for losses as low as 6 dB. In the event that the loss is less than 6 dB or is negative (i.e., gain), this A-value should be discarded.
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| This model's output is only as good as the data on which it is based and the LOS model it is used to correct.
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| ==See also==
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| * [[Egli Model]]
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| * [[Radio propagation model]]
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| * [[Longley–Rice model]]
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| ==References==
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| <references/>
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| {{DEFAULTSORT:Itu Terrain Model}}
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| [[Category:Radio frequency propagation]]
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Oscar is what my wife enjoys to contact me and I totally dig that title. Bookkeeping is what I do. Years ago we moved to North Dakota and I love each working day residing right here. One of the extremely very best issues in the globe for me is to do aerobics and now I'm trying to make money with it.
my weblog at home std testing