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+.. contents::
+   :depth: 3
+..
+
+Link Calculator
+===============
+
+The ‘Link calculator’ analyzes the microwave propagation measurements of
+the wireless links. It can be accessed through the Network Map by
+clicking on the ‘link calculation’ button available in microwave links.
+
+View
+----
+
+The app includes two view possibilities. If it is accessed via the menu,
+the view provides a form table and a blank information table. The form
+table offers inputs for latitude and longitude values of the two points
+of a link. By entering this geographical information the data in the
+information table gets updated.
+
+The information table contains the calculation inputs and outputs. If
+the Link Calculator is accessed through the ‘calculate link’ button,
+only this table with pre-filled geographical locations is shown.
+Currently, input variables of the link calculation include Polarization,
+Frequency, Rain Model, and Rainfall Rate. Outputs of the calculation are
+Free Space Loss and Rain Loss. The results will be visible upon clicking
+the ‘Calculate’ button at the bottom of the table.
+
+Average Mean Sea Level
+~~~~~~~~~~~~~~~~~~~~~~
+
+Denotes the ground elevation of the sites on each end.
+
+Antenna Height Above Ground
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Is the height at which the antenna is mounted from the ground.
+
+Distance
+~~~~~~~~
+
+The distance in the information table is auto-filled when the microwave
+link is selected and the calculator is accessed through the ‘calculate
+link’ button in the Network Map. If the points are entered manually, the
+distance is calculated after clicking the ‘Calculate’ button.
+
+Polarization
+~~~~~~~~~~~~
+
+A selection of Vertical and Horizontal polarization is possible.
+
+Frequency
+~~~~~~~~~
+
+A selection of known and regulated microwave bands is possible.
+
+Rainfall Rate
+~~~~~~~~~~~~~
+
+Rainfall rate can be entered in the field, however if the local
+information is not available, the digital map and rainfall values of
+ITU-R P.837-7  [1]_ is used. The latitude grid is from -90 North degrees
+to +90 North degrees and the longitude grid is from -180 degrees East to
++180 East. For this calculation, the pre-computed R_0.01 map is used. A
+selection is possible through the Rain Model drop-down list. When the
+ITU model is selected, the rainfall rate will be shown in the rainfall
+rate field after clicking the ‘Calculate’ button.
+
+Calculations
+------------
+
+Wireless signal attenuation is calculated based on ITU Recommendations
+for Propagation. At the moment these calculations include the free space
+loss and rain loss.
+
+Free Space Loss
+~~~~~~~~~~~~~~~
+
+Calculates the Free Space Path Loss for a point-to-point non-terrestrial
+link using the recommended formula in ITU-R P.525-4  [2]_. The output is
+shown in dB hence the distance is attributed in the calculation.
+
+Rain Loss
+~~~~~~~~~
+
+Calculates the rain induced attenuation on microwave signal. The
+calculation is based on the recommended formula in ITU-R P.838-3  [3]_,
+taking into account the polarization of the signal, rainfall rate, and
+distance. The manual calculation is also possible if ‘Specific Rain’ is
+selected as rain model. After selecting the inputs, rain loss will be
+calculated by clicking the ‘Calculate’ button.
+
+--------------
+
+.. [1]
+   Radiocommunication Sector of International Telecommunication Union.
+   ITU-R P.837-7: Characteristics of precipitation for propagation
+   modelling 2017.
+
+.. [2]
+   Radiocommunication Sector of International Telecommunication Union.
+   ITU-R P.525-4: Calculation of free-space attenuation 2019.
+
+.. [3]
+   Radiocommunication Sector of International Telecommunication Union.
+   ITU-R P.838-3: Specific attenuation model for rain for use in
+   prediction methods 2005.