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Old 07-23-2008, 06:14 AM
ImranSabir ImranSabir is offline
Join Date: Feb 2008
Location: Pakistan
Posts: 48

On obstructed paths, the Longley-Rice irregular terrain algorithm estimates the loss using the weighted average of the smooth earth loss and the loss of a double knife edge. The weighting factor is based on empirical data and considers the following parameters:

terrain roughness effective antenna heights
frequency horizon angles

For smooth paths, the loss approaches the smooth earth value. For very rough paths the loss approaches the double knife edge value. The Pathloss automatic diffraction algorithm defaults to irregular terrain when the path cannot be characterized as a single or multiple isolated obstacle(s).
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