The different rays arriving at a receiver location create constructive and destructive interference patterns. This is known as the multipath effect. This together with the shadowing effects caused by building obstructions lead to channel fading. In many wireless applications, the total received power by the receiver is all that matters. In some others, the angle of arrival of the rays as well as their polarization are of immense interest. A fully polarimetric, coherent ray tracer like EM.Cube's Shooting-and-Bouncing-Rays (SBR) solver lets you compute and resolve all the rays received by a receiver including their power levels, time delays and angles of arrival.
[[File:manuals/emagware/emcube/modules/propagation/wireless-propagation-primer/the-need-for-wireless-propagation-modeling/urban.png]]
== A Wireless Propagation Primer ==
=== The SBR Method ===
EM.Cube's [[Propagation Module ]] provides an asymptotic ray tracing simulation engine that is based on a technique known as Shooting-and-Bouncing-Rays (SBR). In this technique, propagating spherical waves are modeled as ray tubes or beams that emanate from a source, travel in space, bounce from obstacles and are collected by the receiver. As rays propagate away from their source (transmitter), they begin to spread (or diverge) over distance. In other words, the cross section or footprint of a ray tube expands as a function of the distance from the source. EM.Cube uses an accurate equi-angular ray generation scheme to that produces almost identical ray tubes in all directions to satisfy energy and power conservation requirements.
When a ray hits an obstructing surface, one or more of the following phenomena may happen:
=== SBR As An Asymptotic EM Solver ===
EM.Cube's SBR simulation engine can be used as a versatile and powerful asymptotic electromagnetic (EM) solver. If you compare EM.Cube's [[Propagation Module ]] with its other computational modules, you will notice a lot of similarities. While other modules group objects primarily by their material properties, [[Propagation Module ]] categorizes the types of obstructing surfaces. Besides sharing the same ray-surface interaction mechanisms, all the objects belonging to a surface group also share the same material properties. [[Propagation Module ]] offers similar source types and similar observable types as the other computational modules. For instance, the Hertzian dipole sources used in a SBR simulation are identical to those offered in PO, MoM3D and Planar modules. The plane wave sources are identical across all computational modules. [[Propagation Module]]'s sensor field planes, far field observables (either radiation patterns or RCS) and Huygens surfaces are all fully compatible with EM.Cube's other computational modules.
As an asymptotic EM solver, the SBR engine can be used to model large-scale electromagnetic radiation and scattering problems. An example of this kind is radiation of simple or complex antennas in the presence of large scattering platforms. You have to keep in mind that by using an asymptotic technique in place of a full-wave method, you trade computational speed and lower memory requirements for modeling accuracy. In particular, the SBR method cannot take into account the electromagnetic coupling effects among nearby radiators or scatterers. However, when your scene spans thousands of wavelengths, an SBR simulation might often prove to be your sole practical solution.
An EM.Cube propagation scene typically consists of several elements. At a minimum, you need a transmitter (Tx) at some location to launch rays into the scene and a receiver (Rx) at another location to receive and collect the incoming rays. A transmitter and a receiver together make the simplest propagation scene, representing a free-space line-of-sight (LOS) channel. A transmitter is one of EM.Cube's several source types, while a receiver is one of EM.Cube's several observable types. A simpler source type is a Hertzian dipole. A simpler observable is a field sensor that is used to compute the electric and magnetic fields on a specified plane.
An outdoor propagation scene may involve several buildings (modeled as impenetrable surfaces) and an underlying flat ground or irregular terrain surface. An indoor propagation scene may involve several walls (modeled as thin penetrable surfaces), a ceiling and a floor arranged according to a certain floor plan. You can also build mixed scenes involving both impenetrable and penetrable blocks, possibly along with irregular terrain surfaces. Your sources and observables can be placed anywhere in the scene. Your transmitters and receivers can be placed outdoors or indoors. A complete list of the various elements of a propagation scene is given in the '''Physical Structure''' section of [[Propagation Module]]'s Navigation Tree as follows:
* Impenetrable Surfaces
[[File:PROP14(1).png]]
Figure 1: The Navigation Tree of EM.Cube's [[Propagation Module]].
=== The Various Types Of Surfaces & Blocks ===
* They represent a specular interface between two media of different material compositions for calculating the reflection, transmission and possibly diffraction coefficients.
EM.Cube has generalized the concept of '''Block''' as any object that obstructs and affects radio wave propagation. Rays hit the facets of a block and bounce off the surface of those facets or penetrate them and continue their propagation. Rays also get diffracted off the edges of these blocks. In EM.Cube's [[Propagation Module]], blocks are grouped together by the type of their interaction with rays. EM.Cube currently offers three types of blocks for use in a propagation scene:
# '''Impenetrable Surfaces:''' Rays hit the facets of this type of blocks and bounce back, but they do not penetrate the object. It is assumed that the interior of such blocks or buildings are highly absorptive.
# '''Terrain Surfaces:''' These blocks are used to provide one or more impenetrable, ground surfaces for the propagation scene. Rays simply bounce off terrain objects. The global ground acts as a flat super-terrain that covers the bottom of the entire computational domain.
EM.Cube's [[Propagation Module ]] allows you to define block groups of each of the above three types. Each block group has the same color or texture and its members share the same material properties: permittivity e<sub>r</sub> and conductivity s. Also, all the penetrable surfaces belonging to the same block group have the same wall thickness. You can define many different block groups with certain properties and underneath each introduce many member objects with different geometrical shapes and dimensions. The table below summarizes the characteristics of each block type:
{| class="wikitable"
[[File:PROP14(2).png]]
Figure 1: [[Propagation Module]]'s Impenetrable Surface dialog.
Under an impenetrable block group, you can draw any of EM.Cube's native solid or surface objects or you can import external model files like STEP, IGES or STL. You can change the properties of an impenetrable surface. In the property dialog of the surface group, click on the table that list the properties to select and highlight a row. Then, click the '''Add/Edit''' button to open up the "Edit Layer" dialog. In this dialog, you can change the name of the material and its permittivity and electric conductivity. The box labeled "Specify Loss Tangent" is unchecked by default. If you check it, you can specify the '''Loss Tangent''' of the material, which, in turn, updates the value of electric conductivity at the center frequency of the project. You can also use EM.Cube's Material List, which will be explained later.
[[File:PROP23.png]]
Figure 2: [[Propagation Module]]'s "Edit Layer" dialog corresponding to impenetrable surfaces.
=== Penetrable Surfaces For Indoor Scenes ===
[[File:PROP15(1).png]]
Figure 1: [[Propagation Module]]'s Penetrable Surface dialog.
Under a penetrable surface group, you can draw any of EM.Cube's native solid or surface objects or you can import external model files like STEP, IGES or STL. You can change the properties of a penetrable surface group including its default thickness. In the property dialog of the surface group, click on the table that list the properties to select and highlight a row. Then, click the '''Add/Edit''' button to open up the "Edit Layer" dialog. Similar to the case of impenetrable surfaces, from this dialog, you can change the material properties (permittivity and electric conductivity) as well as '''Thickness''', which is expressed in the project units. You can also use EM.Cube's Material List, which will be explained later.
[[File:PROP25.png]]
Figure 2: [[Propagation Module]]'s "Edit Layer" dialog corresponding to penetrable surfaces.
You can construct several thin walls and arrange them as rooms. A regular room can be built by placing four vertical wall objects together with an optional horizontal wall at the top for the ceiling. Alternatively, you may use EM.Cube's hollow box objects or boxes with one or two capped end(s). '''Keep in mind that all the penetrable surfaces belonging to a group have the same wall thickness, which is initially set to 0.5 project units by default. Also, note that solid CAD objects belonging to a penetrable surface group are treated as air-filled hollow structures.''' The thickness of penetrable surfaces is implied and not visualized when displaying objects in the project workspace.
[[File:PROP15.png]]
Figure 1: [[Propagation Module]]'s Domain Settings dialog.
Most outdoor and indoor propagation scenes include a flat ground at their bottom, which bounces incident rays back into the scene. EM.Cube's [[Propagation Module ]] provides a global flat ground at z = 0. The global ground indeed acts as an impenetrable surface that blocks the entire computational domain from the z = 0 plane downward. It is displayed as a translucent green plane at z = 0 extending downward. The color of the ground plane is always the same as the color of the ray domain. The global ground is assumed to be made of a homogeneous dielectric material with a specified permittivity e<sub>r</sub> and electric conductivity s. By default, a rocky ground is assumed with e<sub>r</sub> = 5 and s = 0.005 S/m. You can remove the global ground, in which case, you will have a free space scene. To disable the global ground, open up the Global Ground Settings Dialog, which can be accessed by right clicking on the '''Global Ground''' item in the Navigation Tree and selecting '''Global Ground Settings... '''Remove the check mark from the box labeled '''"Include Half-Space Ground (z<0)"''' to disable the global ground. This will also remove the green translucent plane from the bottom of your scene. You can also change the material properties of the global ground and set new values for the permittivity and electric conductivity of the impenetrable, half-space, dielectric medium. '''Do not forget to disable the global ground if you want to model a free space propagation scene.'''
[[File:PROP4.png]]
Figure 2: [[Propagation Module]]'s Global Ground Settings dialog.
=== Terrain Surfaces vs. Global Ground ===
[[File:PROP16.png]]
Figure 1: [[Propagation Module]]'s Terrain dialog.
You can change the properties of a terrain surface group from its property dialog. Click on the table that list the properties to select and highlight a row. Then, click the '''Add/Edit''' button to open up the "Edit Layer" dialog, which is identical to the case of impenetrable surfaces. You can also use EM.Cube's Material List, which will be explained later. When a new terrain type is created, its node on the Navigation Tree becomes active. Under this node you can create and add new terrain objects. When a terrain node is active for drawing, all CAD object creation tools are disabled. You have three options for creating a new terrain object, which will be described in detail in the next sections of this manual:
[[File:PROP18.png]]
Figure 1: [[Propagation Module]]'s Terrain Generator dialog.
Some surface types have an additional shape factor called '''Alpha''' that is identical to the alpha parameter in the surface generator. For example, a Gaussian Hump is defined as exp(-r<sup>2</sup>/(2a<sup>2</sup>)), where r is the polar radius. For a Super-quadratic Hump, the input parameter a defines the degree of the super-quadratic surface. a = 2 corresponds to an ellipsoid. Larger values of a get close to a rectangular base with rounded corners. An undulated sinusoidal surface is defined by cos(pax/D<sub>x</sub>)*cos(pay/D<sub>y</sub>), and an undulated sinc is defined by D<sub>x</sub>*D<sub>y</sub>*sin(pax/D<sub>x</sub>)*sin(pay/D<sub>x</sub>)/(2pxy), where D<sub>x</sub> and D<sub>y</sub> are the X and Y dimensions, respectively. Terrain Generator creates a unit cell based on the specified surface type. From the same dialog, you can also produce an array arrangement of such unit cells. Simply enter any number of elements along the X and Y directions in the boxes labeled '''Array'''.
=== Importing & Exporting Terrain Models ===
You can import two types of terrain in EM.Cube's [[Propagation Module]]. The first type is "'''.TRN"''' terrain file, which is EM.Cube's native terrain format. It is a basic digital elevation map with a very simple ASCII data file format. The resolution of the terrain map in the X and Y directions is specified in meters as STEPS. The (x, y, z) coordinates of the terrain points are then listed one point per line. The other type of terrain format supported by EM.Cube is the standard '''7.5min DEM''' file format with a '''.DEM''' file extension.
To import an external terrain model, first you have to create a terrain group node in the Navigation Tree. Right click on the name of the terrain group in the Navigation Tree and select either '''Import Terrain...''' or '''Import DEM File...''' A standard Windows '''Open Dialog''' opens up, with the file type set to .TRN or .DEM extensions, respectively. You can browse your folders and find the right terrain model file to import.
You can also export all the terrain objects in the project workspace as a terrain file with a '''.TRN''' file extension. You can even import a DEM terrain model from an external file and then save and export it as a native terrain (.TRN) file. To export the terrain, select '''File''' > '''Export...''' from [[Propagation Module]]'s '''File Menu'''. The standard Windows Save Dialog opens up with the default file type set to '''.TRN'''. Type in a name for your new terrain file and click the '''Save''' button to export the terrain data.
[[File:manuals/emagware/emcube/modules/propagation/terrain/importing-external-terrain/prop_manual-12_tn.png]]
Most of the time, your outdoor propagation scene consists of simple buildings made of single-layer walls with standard material properties (e<sub>r</sub> and s). In the case of a single-layer impenetrable surface, the specular interface is an infinite dielectric half-space, which reflects the impinging rays. Single-layer penetrable surfaces, on the other hand, involve finite-thickness dielectric walls, which both reflect and transmit the incident rays. Similarly, most of your indoor propagation scenes involve simple single-layer penetrable walls with the specified material properties e<sub>r</sub> and s. A thin wall acts like a finite-thickness dielectric slab that both reflects and transmits incident rays. In the case of the global ground or terrain objects, only ray reflection off the ground surface is considered.
In EM.Cube's [[Propagation Module]], you can define multilayer surfaces with both reflection and transmission properties. You can define multilayer impenetrable buildings, multilayer penetrable walls, and multilayer terrain, with an arbitrary number of layers having different material compositions. You define a multilayer surface in the property dialog of a block, whether impenetrable, penetrable or terrain. In the section entitled '''Surface Type''', two options are available: '''Standard Material''' or '''User Defined Model'''. For simple multilayer walls, select the '''Standard Material''' option. You can add new layers with arbitrary thickness and material parameters to the existing layers. To insert a new layer, deselect any items in the layer list, and click the '''Add/Edit''' button to open the "Add Layer" Dialog. Here you can enter a name for the new layer and values for its '''Thickness''', e<sub>r</sub> and s. You may also delete any layer by selecting and highlighting it and clicking the '''Delete''' button. You can move layers up or down using the '''Move Up''' and '''Move Down''' buttons and change the layer hierarchy.
You can also search EM.Cube's material database by clicking the '''Material''' button of "Add Layer" or "Edit Layer" dialogs. This opens the '''Materials''' Dialog. Inside the material list select and highlight any row and click the '''OK''' button. The selected material will fill out all the fields in the "Add Layer" or "Edit Layer" dialogs. Inside the Materials Dialog, you can type the few first letters of any material, and it will take you to the corresponding row of the list.
=== Transferring Objects From Or To Other Modules ===
When you start a new project in EM.Cube's [[Propagation Module ]] and draw a solid object like a box in the project workspace without having defined any surface groups, it is assumed to be of the impenetrable surface type. A default impenetrable surface group called Block_1 is automatically added to the Navigation Tree, which holds your newly drawn object. The default group has the material properties of "Brick" (e<sub>r</sub> = 4.4 and s = 0.001 S/m.) with a dark brown color. You can continue drawing new objects in the project workspace and adding them under this block node. Or you can define a new surface type with different properties. By default, the last surface group that was defined is '''Active'''. The current active surface group is always listed in bold letters in the Navigation Tree. When you draw a new object, it is always inserted under the current active surface group. Any surface group can be activated by right clicking its name in the Navigation Tree and selecting the '''Activate''' item of the contextual menu.
You can move any object from its current surface group into any other available surface group. First select the object, then right click on its surface and select '''MoveTo > Propagation >'''. A submenu appears which lists all the available surface groups where you can transfer the selected object. You can also move objects among surface groups by selecting their names in the Navigation Tree and using the contextual menu. In a similar way, you can transfer objects from [[Propagation Module ]] to EM.Cube's other modules or vice versa. '''Keep in mind that all the external model files such as STEP, IGES, STL, etc. are first imported to EM.Cube's CubeCAD, from which you can transfer them to other modules.''' First select the object, then right click and select '''MoveTo >'''. In the submenu you will see a list of all the EM.Cube modules that have at least one available group where you can transfer your selected object. You can select multiple objects for transfer. When using the keyboard's '''Shift Key''' or '''Ctrl Key''' for multiple selection, make sure that those keys are held down, when you right click to access the contextual menu.
== Defining Sources & Observables ==
Like every other electromagnetic solver, EM.Cube's SBR ray tracer requires a source for excitation and one or more observables for generation of simulation data. EM.Cube's new [[Propagation Module ]] offers several types of sources and observables for a SBR simulation. You can mix and match different source types and observable types depending on the requirements of your modeling problem. There are two types of sources:
* [[#Defining Transmitter Sets|Transmitter]]
=== Hertzian Dipole Sources ===
Earlier versions of EM.Cube's [[Propagation Module ]] used to offer an isotropic radiator with vertical or horizontal polarization as the simplest transmitter type. This release of EM.Cube has abandoned isotropic radiator transmitters because they do not exist physically in a real world. Instead, the default transmitter radiator type is now a Hertzian dipole. Note that before defining a transmitter, first you have to define a base set to establish the location of the transmitter. Most simulation scenes involve only a single transmitter. Your base set can be made up of a single point for this purpose.
To define a new Transmitter Set, go to the '''Sources''' section of the Navigation Tree, right click on the '''Transmitters''' item and select '''Insert Transmitter...''' A dialog opens up that contains a default name for the new Transmitter Set as well as a dropdown list labeled '''Select Base Set'''. In this list you will see all the available base sets already defined in the project workspace. Select the desired base set to associate with the transmitter set. Note that if the base set contains more than one point, then more than one transmitter will be created and contained in your transmitter set. After defining a transmitter set, the base points change their color to the transmitter color, which is red by default.
[[File:PROP18(1).png]]
Figure 1: [[Propagation Module]]'s Transmitter dialog with a short dipole radiator selected.
=== Defining Base Point Sets ===
[[File:PROP1.png]]
Figure 1: [[Propagation Module]]'s Base Set dialog.
Once a base set node has been added to the Navigation Tree, it becomes the active node for new object drawing. Under base sets, you can only draw point objects. All other object creation tools are disabled. A point is initially drawn on the XY plane. Make sure to change the Z-coordinate of your radiator, otherwise, it will fall on the global ground at z = 0. You can also create arrays of base points under the same base set. This is particularly useful for setting up receiver grids to compute coverage maps. Simply select a point object and click the '''Array Tool''' of '''Tools Toolbar''' or use the keyboard shortcut "A". Enter values for the X, Y or Z spacing as well as the number of elements along these three directions in the Array Dialog. In most propagation scenes you are interested in 2D horizontal arrays along a fixed Z coordinate (parallel to the XY plane).
</table>
Figure 1: [[Propagation Module]]'s Transmitter dialog with a user defined radiator selected.
=== Multiple Transmitters vs. Antenna Arrays ===
</table>
Figure 1: [[Propagation Module]]'s Receiver dialog.
=== Defining Field Sensors ===
[[File:PMOM90.png]]
Figure 1: [[Propagation Module]]'s Field Sensor dialog.
Once you close the Field Sensor dialog, its name is added under the '''Field Sensors''' node of the Navigation Tree. At the end of a SBR simulation, the field sensor nodes in the Navigation Tree become populated by the magnitude and phase plots of the three vectorial components of the electric ('''E''') and magnetic ('''H''') field as well as the total electric and magnetic fields defined in the following manner:
In a typical SBR simulation, a ray is traced from the location of the source until it hits a scatterer. The SBR method assumes that the ray hits either a flat facet of the scatterer or one of its edges. In the case of hitting a flat facet, the specular point is used to launch new reflected and transmitted rays. The surface of the facet is treated as an infinite dielectric medium interface, at which the reflection and transmission coefficients are calculated. In the case of hitting an edge, new diffracted rays are generated in the scene. However, only those who reach a nearby receiver in their line of sight are ever taken into account. In other words, diffractions are treated locally.
EM.Cube's [[Propagation Module ]] allows you to draw any type of surface or solid CAD objects under impenetrable and penetrable surface groups. Some of these objects have flat faces such as boxes, pyramids, rectangle or triangle strips, etc. Some others contain curved surfaces or curved boundaries such as cylinders, cones, etc. All the non-flat surfaces have to be discretized in the form of a collection of smaller flat facets. EM.Cube uses a triangular surface mesh generator to discretize the penetrable and impenetrable surface objects of your propagation scene. This mesh generator is very similar to the ones used in EM.Cube's two other modules: MoM3D and Physical Optics (PO).
You can build a variety of surface and solid objects using EM.Cube's native "Curve" CAD objects like lines, polylines, circles, etc. You can use tools like Extrude, Loft, Strip-Sweep, Pipe-Sweep, etc. to transform curves into surface or solid objects. '''However, keep in mind that all the "Curve" CAD objects are ignored by the SBR mesh generator and are therefore not sent to the simulation engine.'''
[[File:manuals/emagware/emcube/modules/propagation/discretizing-the-scene/customizing-prismatic-mesh/prop_manual-29.png]]
Figure 1: [[Propagation Module]]'s Mesh Settings dialog.
=== Special Discretized Object Types ===
== Running A SBR Simulation ==
EM.Cube's [[Propagation Module ]] offers three types of ray tracing simulations:
* Analysis
An SBR analysis is the simplest ray tracing simulation and involves the following steps:
# Set the unit of project scene and the frequency of operation. Note that EM.Cube's default project unit is millimeter. When working with the [[Propagation Module]], pay attention to the project unit. Radio propagation problems usually require meter, mile or kilometer as the project unit.
# Create the blocks and draw the buildings at the desired locations.
# Keep the default ray domain and accept the default global ground or change its material properties.
# Visualize the coverage map and plot other data.
You can access the [[Propagation Module]]'s run dialog by clicking the '''Run''' [[File:manuals/emagware/emcube/modules/propagation/running-a-sbr-simulation/simulation-setup/run_icon.png]] button of the '''Simulate Toolbar''' or by selecting '''Simulate > Run...''' or using the keyboard shortcut '''Ctrl+R'''. When you click the '''Run''' button, a new window opens up that reports the different stages of the SBR simulation and indicates the progress of each stage. After the SBR simulation is successfully completed, a message pops up and prompts the completion of the process.
[[File:PROP12.png]]
Figure 1: [[Propagation Module]]'s Simulation Run dialog.
=== SBR Simulation Parameters ===
[[File:PROP13.png]]
Figure 1: [[Propagation Module]]'s SBR Engine Settings dialog.
=== The Coverage Map ===
=== Plotting Other Simulation Results ===
Besides visualizing the coverage map and received rays in the EM.CUBE's [[Propagation Module]], you can also plot the '''Path Loss''' of all the receivers belonging to a receiver set as well as the '''Power Delay Profile''' of individual receivers. To plot these data, go the '''Observables''' section of the Navigation Tree and right click on the '''Receivers''' item. From the context menu, select '''Plot Path Loss''' or '''Plot Power Delay Profile''', respectively. The path loss data between the active transmitter and all the receivers belonging to a receiver set are plotted on a Cartesian graph. The horizontal axis of this graph represents the index of the receiver. Power Delay Profile is a bar chart that plots the power of individual rays received by the currently selected receiver versus their time delay. If there is a line of sight (LOS) between a transmitter and receiver, the LOS ray will have the smallest delay and therefore will appear first in the bar chart. Sometimes you may have several rays arriving at a receiver at the same time, i.e. all with the same delay, but with different power level. These will appear as stacked bars in the chart.
You can also plot the path loss and power delay profile graphs and many others from EM.CUBE's data manager. You can open data manager by clicking the '''Data Manager''' [[File:manuals/emagware/emcube/modules/propagation/running-a-sbr-simulation/plotting-other-simulation-results/data_manager_icon.png]] button of the '''Compute Toolbar''' or by selecting '''Compute [[File:manuals/emagware/emcube/modules/propagation/hybrid-simluations/illuminating-periodic-walls-using-sbr/larrow_tn.png]]Data Manager''' from the menu bar or by right clicking on the '''Data Manager''' item of the Navigation Tree and selecting Open Data Manager... from the contextual menu or by using the keyboard shortcut '''Ctrl+D'''. In the Data manager Dialog, you will see a list of all the data files available for plotting. These include the theta and phi angles of arrival and departure of the selected receiver. You can select any data file by clicking and highlighting its '''ID''' in the table and then clicking the '''Plot''' button.
=== Running A Frequency Sweep With SBR ===
By default, you run a single-frequency simulation in EM.CUBE's [[Propagation Module]]. You set the operational frequency of a SBR simulation in the project's '''Frequency Dialog''', which can be accessed in a number of ways:
# By clicking the '''Frequency''' [[File:manuals/emagware/emcube/modules/propagation/running-a-sbr-simulation/running-a-frequency-sweep-with-sbr/freq_icon.png]] button of the '''Compute Toolbar'''.
EM.CUBE's coverage maps display the received power at the location of all the receivers. The receivers together from a set/ensemble, which might be uniformly spaced or distributed across the propagation scene or may consist of randomly scattered radiators. Every coverage map shows the '''Mean''' and '''Standard Deviation''' of the received power for all the receivers involved. These information are displayed at the bottom of the coverage map's legend box and are expressed in dB.
In the [[Propagation Module]], when you ran a sweep simulation (frequency, transmitter or parametric), you also have the option to generate two additional coverage maps: one for the mean of all the individual sample coverage maps and another for their standard deviation. To do so, in the '''Run Dialog''', check the box labeled '''"Create Mean and Standard Deviation Coverage Maps"'''. Note that the mean and standard deviation values displayed on the individual coverage maps correspond to the spatial statistics of the receivers in the scene, while the mean and standard deviation coverage maps correspond to frequency, transmitter or variable sets defined for the sweep simulation. Also, note that both of the mean and standard deviation coverage maps have their own spatial mean and standard deviation values expressed in dB at the bottom of their legend box.
[[File:manuals/emagware/emcube/modules/propagation/running-a-sbr-simulation/statistical-analysis-of-propagation-scene/prop_run21_tn.png]]