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[[Image:Splash-prop.jpg|right|800px720px]]

[[Image:Tutorial_icon.png|40px30px]] '''[[EM.Cube#EM.Terrano_Tutorial_Lessons | EM.Terrano Tutorial Gateway]]'''

[[Image:Back_icon.png|40px30px]] '''[[EM.Cube | Back to EM.Cube Main Page]]'''

[[EM.Terrano ]] is a physics-based, site-specific, wave propagation modeling tool that enables engineers to quickly determine how radio waves propagate in urban, natural or mixed environments. [[EM.Terrano]]'s simulation engine is equipped with a fully polarimetric, coherent ray tracing solver based on the Shooting-and-Bouncing-Rays (SBR) method, which utilizes geometrical optics (GO) in combination with uniform theory of diffraction (UTD) models of building edges. [[EM.Terrano ]] lets you analyze and resolve all the rays transmitted from one ore more signal sources, which propagate in a real physical site channel made up of buildings, terrain and other obstructing structures. [[EM.Terrano ]] finds all the rays received by a receiver at a particular location in the physical site and computes their vectorial field and power levels, time delays, angles of arrivaland departure, etc. Using [[EM.Terrano ]] you can examine the connectivity of a communication link between any two points in a real specific propagation site.

Since its introduction in 2002, [[EM.Terrano ]] has helped wireless engineers around the globe model the physical channel and the mechanisms by which radio signals propagate from transmitters to receiversin various environments. [[EM.Terrano’s Terrano]]’s advanced ray tracing simulator finds the dominant propagation paths at each specific physical site. It calculates the true signal characteristics at the actual locations using physical databases of the buildings and terrain at a given site, not those of a statistically average or representative environment. The earlier versions of [[EM.Terrano]]'s SBR solver relied on certain assumptions and approximations such as the vertical plane launch (VPL) method or 2.5D analysis of urban canyons with prismatic buildings using two separate vertical and horizontal polarizations. In 2014, we introduced a new fully 3D polarimetric SBR solver that accurately traces all the three X, Y and Z components of the electric fields (both amplitude and phase) at every point inside the computational domain. Using a full 3D CAD modeler, you can now set up any number of buildings with arbitrary geometries, no longer limited to vertical prismatic shapes. Versatile interior wall arrangements allow indoor propagation modeling inside complex building configurations. The most significant recent improvement development is an entirely new a multi-core parallelized SBR simulation engine that takes advantage of ultrafast k-d tree algorithms borrowed from the field of computer graphics and video gamingto achieve the ultimate efficiency in geometrical optics ray tracing.

[[Image:Tutorial_iconInfo_icon.png|40px30px]] Click here to access learn more about the '''[[EM.Cube#EM.Terrano_Tutorial_Lessons Basic Principles of SBR Ray Tracing | EM.Terrano Tutorial GatewayBasic SBR Theory]]'''.

[[Image:PROP250AManhattan1.png|thumb|left|720px420px|A large urban propagation scene featuring lower Manhattan.]]

[[EM.Terrano ]] is the ray tracing '''Propagation Module''' of '''[[EM.Cube]]''', a comprehensive, integrated, modular electromagnetic modeling environment. EM.Teranno shares the visual interface, 3D parametric CAD modeler, data visualization tools, and many more utilities and features collectively known as [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD ]] with all of [[EM.Cube]]'s other computational modules.

With the seamless integration of [[EM.Terrano ]] with [[EM.Cube]]'s other modules, you can now model complex antenna systems in [[EM.Tempo]], [[EM.Libera]], [[EM.Picasso]] or [[EM.Illumina]], and generate antenna radiation patterns that can be used to model directional transmitters and receivers at the two ends of your propagation channel. Conversely, you can analyze a propagation scene in [[EM.Terrano]], collect all the rays received at a certain receiver location and import them as coherent plane wave sources to [[EM.Tempo]], [[EM.Libera]], [[EM.Picasso]] or [[EM.Illumina]].

=== Advantages & Limitations of EM.Terrano's SBR Solver === [[Image:Info_iconEM.png|30pxTerrano]] Click here 's SBR simulation engine utilizes an intelligent ray tracing algorithm that is based on the concept of k-dimensional trees. A k-d tree is a space-partitioning data structure for organizing points in a k-dimensional space. k-d trees are particularly useful for searches that involve multidimensional search keys such as range searches and nearest neighbor searches. In a typical large radio propagation scene, there might be a large number of rays emanating from the transmitter that may never hit any obstacles. For example, upward-looking rays in an urban propagation scene quickly exit the computational domain. Rays that hit obstacles on their path, on the other hand, generate new reflected and transmitted rays. The k-d tree algorithm traces all these rays systematically in a very fast and efficient manner. Another major advantage of k-d trees is the fast processing of multi-transmitters scenes.  [[EM.Terrano]] performs fully polarimetric and coherent SBR simulations with arbitrary transmitter antenna patterns. Its SBR simulation engine is a true asymptotic &quot;field&quot; solver. The amplitudes and phases of all the three vectorial field components are computed, analyzed and preserved throughout the entire ray tracing process from the source location to learn more about the basic functionality field observation points. You can visualize the magnitude and phase of '''all six electric and magnetic field components at any point in the computational domain. In most scenes, the buildings and the ground or terrain can be assumed to be made of homogeneous materials. These are represented by their electrical properties such as permittivity &epsilon;_r and electric conductivity &sigma;. More complex scenes may involve a multilayer ground or multilayer building walls. In such cases, one can no longer use the simple reflection or transmission coefficient formulas for homogeneous medium interfaces. [[Building_Geometrical_Constructions_in_CubeCAD | CubeCADEM.Terrano]]calculates the reflection and transmission coefficients of multilayer structures as functions of incident angle, frequency and polarization and uses them at the respective specular points.  It is very important to keep in mind that SBR is an asymptotic electromagnetic analysis technique that is based on Geometrical Optics (GO) and the Uniform Theory of Diffraction (UTD). It is not a &quot;full-wave&quot; technique, and it does not provide a direct numerical solution of Maxwell'''s equations.SBR makes a number of assumptions, chief among them, a very high operational frequency such that the length scales involved are much larger than the operating wavelength. Under this assumed regime, electromagnetic waves start to behave like optical rays. Virtually all the calculations in SBR are based on far field approximations. In order to maintain a high computational speed for urban propagation problems, [[EM.Terrano]] ignores double diffractions. Diffractions from edges give rise to a large number of new secondary rays. The power of diffracted rays drops much faster than reflected rays. In other words, an edge-diffracted ray does not diffract again from another edge in [[EM.Terrano]]. However, reflected and penetrated rays do get diffracted from edges just as rays emanated directly from the sources do. <table><tr><td> [[Image:Multipath_Rays.png|thumb|left|500px|A multipath urban propagation scene showing all the rays collected by a receiver.]]</td></tr></table>

Buildings/blocks with arbitrary geometries and material properties including multilayer walls and user defined macromodels</li>

Buildings/blocks with impenetrable surfaces or penetrable surfacesusing thin wall approximation</li>

Terrain with arbitrary material properties including lossy multilayer ground, user defined macromodels or an empirical soil modelMultilayer walls for indoor propagation scenes</li>

Native terrain generator Penetrable volume blocks with terrain catalog arbitrary geometries and user defined equation-based surface profiles including random rough surface terrainmaterial properties</li>

Import of shape shapefiles and STEP, IGES abnd STL CAD model files for scene construction</li>

Import of digital elevation map (DEM) terrainTerrain surfaces with arbitrary geometries and material properties and random rough surface profiles</li>

Penetrable volume blocks with arbitrary material properties or based on fog, rain or Weissberger vegetation Import of digital elevation map (DEM) terrain models</li>

Easy construction Python-based random city wizard with randomized building locations, extents and orientations</li> <li> Python-based wizards for generation of indoor scenes using arbitrary penetrable surfaces parameterized multi-story office bulidings and several terrain scene types</li> <li> Standard half-wave dipole transmitters and receivers orinted along the principal axes</li> <li> Short Hertzian dipole sources with thin wall definitionsarbitrary orientation</li> <li> Isotropic receivers or receiver grids for wireless coverage modeling</li>

Triangular surface mesher mesh generator for discretization of arbitrary block geometries</li>

Ray reflection, edge diffraction and ray transmission through multilayer thin walls and material volumes</li>

User defined macromodels for reflection and transmission coefficients Incredibly fast frequency sweeps of blocks and terrain (imported from other modules or external files)the entire propagation scene in a single SBR simulation run</li>

Real-time superposition of synchronized transmitters</li> <li> Incredibly fast frequency sweeps of the entire propagation scene</li> <li> Parametric sweeps of scene elements like building properties, or radiator heights and rotation angles, or superheterodyne transmitter and receiver parameters</li>

Remote simulation capability</li> <li> Both Windows and Linux versions of SBR simulation engine availablePolarimetric channel characterization for MIMO analysis using orthogonally polarized isotropic radiators</li>

A typical propagation scene in [[EM.Terrano ]] 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. In [[EM.Terrano|EM.TErrano]], a transmitter represents a point source, while a receiver represents a point observable. Both a transmitter and a receiver are associated with point objects, which are one of the many types of geometric objects you can draw in the project workspace. Your scene might involve more than one transmitter and possibly a large grid of receivers.

A more complicated propagation scene usually contains several buildings, walls, or other kinds of scatterers and wave obstructing objects. You models all of these by drawing geometric objects in the project workspace or by importing external CAD models. [[EM.Terrano ]] does not organize the geometric objects of your project workspace by their material composition. Rather, it groups the geometric objects into blocks based on a common type of interaction with incident rays. [[EM.Terrano ]] offer the following types of object blocks:

Impenetrable surfaces, penetrable surfaces, terrain surfaces and penetrable volumes represent all the objects that obstruct the propagation of electromagnetic waves (rays) in the free space. What differentiates them is the types of physical phenomena that are used to model their interaction with the impinging rays. [[EM.Terrano ]] discretizes geometric objects into a number of flat facets. The field intensity, phase and power of the reflected and transmitted rays depend on the material properties of the obstructing facet. The specular surface of a facet can be modeled as a simple homogeneous dielectric half-space or as a multilayer medium. In that respect, all the obstructing objects such as buildings, walls, terrain, etc. behave in a similar way:

In [[EM.Terrano]], all the geometric objects associated with the various scene elements like buildings, terrain surfaces and base location points are grouped together as blocks based on their common type. All the objects listed under a particular group in the navigation tree share the same color, texture and material properties. Once a new block group has been created in the navigation tree, it becomes the "Active" group of the project workspace, which is always displayed in bold letters. You can draw new objects under the active node. Any block group can be made active by right-clicking on its name in the navigation tree and selecting the '''Activate''' item of the contextual menu.

It is recommended that you first create block groups, and then draw new objects under the active block group. However, if you start a new [[EM.Terrano ]] project from scratch, and start drawing a new object without having previously defined any block groups, a new default impenetrable surface group is created and added to the navigation tree to hold your new CAD object. You can always change the properties of a block group later by accessing its property dialog from the contextual menu. You can also delete a block group with all of its objects at any time.

{{Note|You can only import external CAD models (STEP, IGES, STL, DEM, etc.) only to the CubeCAD module. You can then transfer the imported objects from CubeCAD to [[EM.Terrano]].}}

You can move any geometric object or a selection of objects from one block group to another. You can also transfer objects among [[EM.Cube]]'s different modules. For example, you often need to move imported CAD models of terrain or buildings from CubeCAD to [[EM.Terrano]]. To transfer objects, first select them in the project workspace or select their names in the navigation tree. Then right-click on them and select <b>Move To &rarr; Module Name &rarr; Object Group</b> from the contextual menu. For example, if you want to move a selected object to a block group called "Terrain_1" in [[EM.Terrano]], then you have to select the menu item '''Move To &rarr; [[EM.Terrano ]] &rarr; Terrain_1''' as shown in the figure below. Note that you can transfer several objects altogether using the keyboards's {{key|Ctrl}} or {{key|Shift}} keys to make multiple selections.

[[Image:PROP MAN6.png|thumb|left|480px360px|A set of buildings on an undulating terrain without elevation adjustment.]]

[[Image:PROP MAN7.png|thumb|left|480px360px|The set of buildings on the undulating terrain after elevation adjustment.]]

Most outdoor and indoor propagation scenes include a flat ground at their bottom, which bounces incident rays back into the scene. [[EM.Terrano ]] 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 &epsilon;_r and electric conductivity &sigma;. By default, a rocky ground is assumed with &epsilon;_r = 5 and &sigma; = 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 '''&quot;Include Half-Space Ground (z&lt;0)&quot;''' 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.

Alternatively, you can use [[EM.Terrano]]'s '''Empirical Soil Model''' to define the material properties of the global ground. This model requires a number of parameters: Temperature in &deg;C, and Volumetric Water Content, Sand Content and Clay Content all as percentage.

{{Note|To model a free-space propagation scene, you have to disable [[EM.Terrano]]'s default global ground.}}

Transmitters act as sources in a propagation scene. A transmitter is a point radiator with a fully polarimetric radiation pattern defined over the entire 3D space in the standard spherical coordinate system. By default, [[EM.Terrano ]] assumes that your transmitter is a vertically polarized half-wave resonant dipole antenna. This antenna has an almost omni-directional radiation pattern in all azimuth directions. It also has radiation nulls along the axis of the dipole. You can override the default radiator option and select any other kind of antenna with a more complicated radiation pattern. For this purpose, you have to import a radiation pattern data file to [[EM.Terrano]]. You can model any radiating structure using [[EM.Cube]]'s other computational modules, [[EM.Tempo]], [[EM.Picasso]], [[EM.Libera]] or [[EM.Illumina]], and generate a 3D radiation pattern data file for it. The far-field radiation patter data are stored in a specially formatted file with a &quot;'''.RAD'''&quot; file extension. This file contains columns of spherical &phi; and &theta; angles as well as the real and imaginary parts of the complex-valued far-zoned electric field components '''E_&theta;''' and '''E_&phi;'''. The &theta;- and &phi;-components of the far-zone electric field determine the polarization of the transmitting radiator.

{{Note|By default, [[EM.Terrano ]] assume a vertical half-wave dipole radiator for your transmitter set. The radiation pattern data file of this radiator is called "DPL_STD.RAD" and it is located in inside the "EMAG &rarr; Models" sub-folder under the Documents folder.}}

Once you define a new transmitter set, its name is added in the '''Transmitters''' section of the navigation tree. The color of all the base points associated with the newly defined transmitter set changes, and an additional little ball with the transmitter color (red by default) appears at the location of each associated base point. You can open the property dialog of the transmitter set and modify a number of parameters including the '''Baseband Power''' in Watts and the broadcast signal '''Phase''' in degrees. The default transmitter power level is 1W or 30dBm. There is also a check box labeled '''Custom Power''', which is checked by default. In that case, the power and phase boxes are enabled and you can change the default 1W power and 0&deg; phase values as you wish. [[EM.Cube]]'s ".RAD" radiation pattern files usually contain the value of &quot;Total Radiated Power&quot; in their file header. This quantity is calculated based on the particular excitation mechanism that was used to generate the pattern file in the original [[EM.Cube]] module. When the "Custom Power" check box is unchecked, [[EM.Terrano ]] will use the total radiated power value of the radiation file for the SBR simulation.

Receivers act as observables in a propagation scene. The objective of a SBR simulation is to calculate the far-zone electric fields and the total received power at the location of a receiver. You need to define at least one receiver in the scene before you can run a SBR simulation. Similar to a transmitter, a receiver is a point radiator, too. However, unlike the transmitter case, [[EM.Terrano ]] assumes that your receiver, by default, is an isotropic radiator. An isotropic radiator has a perfect omni-directional radiation pattern in all azimuth and elevation directions. An isotropic radiator doesn't physically exist in the real world. But the assumption of a default, polarization-matched, isotropic receiver is a convenient choice to generate received power coverage maps of a propagation scene. You might also define a complicated radiation pattern for your receiver set. In that case, you need to import a radiation pattern data file to [[EM.Terrano]]. Note that you can simply use the data file "DPL_STD.RAD" for that purpose, which is also used by [[EM.Terrano ]] for the definition of the default vertical half-wave dipole transmitter.

{{Note| [[EM.Terrano ]] receivers, by default, are defined as polarization-matched isotropic radiators.}}

[[EM.Terrano]]'s Transmitter Set dialog and Receiver Set dialog both allow you to rotate an imported radiation pattern. In that case, you need to specify the '''Rotation''' angles in degrees about the X-, Y- and Z-axes. It is important to note that these rotations are performed sequentially and in the following order: first a rotation about the X-axis, then a rotation about the Y-axis, and finally a rotation about the Z-axis. In addition, all the rotations are performed with respect to the "rotated" local coordinate systems (LCS). In other words, the first rotation with respect to the local X-axis transforms the XYZ LCS to a new primed X^&prime;Y^&prime;Z^&prime; LCS. The second rotation is performed with respect to the new Y^&prime;-axis and transforms the X^&prime;Y^&prime;Z^&prime; LCS to a new double-primed X^{&prime;&prime;}Y^{&prime;&prime;}Z^{&prime;&prime;} LCS. The third rotation is finally performed with respect to the new Z^{&prime;&prime;}-axis. The figures below shows single and double rotations.

When your transmitters or receivers are located above a flat terrain like the global ground, their Z-coordinates are equal to their height above the ground, as the terrain elevation is fixed and equal to zero everywhere. In many propagation modeling problems, your transmitters and receivers may be located above an irregular terrain with varying elevation across the scene. In that case, you may want to place your transmitters or receivers at a certain height above the underlying ground. The Z-coordinate of a transmitter or receiver is now the sum of the terrain elevation at the base point and the specified height. [[EM.Terrano ]] gives you the option to adjust the transmitter and receiver sets to the terrain elevation. This is done for individual transmitter sets and individual receiver sets. At the top of the Transmitter Dialog there is a check box labeled &quot;'''Adjust Tx Sets to Terrain Elevation'''&quot;. Similarly, at the top of the Receiver Dialog there is a check box labeled &quot;'''Adjust Rx Sets to Terrain Elevation'''&quot;. These boxes are unchecked by default. As a result, your transmitter sets or receiver sets coincide with their associated base points in the project workspace. If you check these boxes and place a transmitter set or a receiver set above an irregular terrain, the transmitters or receivers are elevated from the location of their associated base points by the amount of terrain elevation as can be seen in the figure below.

Like every other electromagnetic solver, [[EM.Terrano]]'s SBR ray tracer requires an excitation source and one or more observables for the generation of simulation data. [[EM.Terrano ]] offers several types of sources and observables for a SBR simulation. You already learned about the transmitter set as a source and the receiver set as an observable. You can mix and match different source types and observable types depending on the requirements of your modeling problem.

The available source types in [[EM.Terrano ]] are:

The available observables types in [[EM.Terrano ]] are:

where P_t is the baseband signal power in dBm at the transmitter, G_TC and G_RC are the total transmitter and receiver chain gains in dB, respectively, G_TA and G_RA are the total transmitting and receiving antenna gains in dB, respectively, and PL is the channel path loss in dB. Keep in mind that [[EM.Terrano ]] is fully polarimetric. The transmitting and receiving antenna characteristics are specified through the imported radiation pattern files, which are part of the definition of the transmitters and receivers. In particular, the polarization mismatch losses are taken into account through the polarimetric SBR ray tracing analysis.

At the end of an SBR simulation, [[EM.Terrano ]] writes a number of ASCII data files to your project folder. The main output data file is called "sbr_results.RTOUT". This file contains all the information about individual receivers and the [[parameters]] of each ray that is received by each individual receiver.

Besides "sbr_results.out", [[EM.Terrano ]] writes a number of other ASCII data files to your project folder. You can view or plot these data in [[EM.Cube]]'s Data Manager. You can open data manager by clicking the '''Data Manager''' [[File:data_manager_icon.png]] button of the '''Simulate Toolbar''' or by selecting '''Menu > Simulate > 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 {{key|Ctrl+D}}.

When you run a frequency or parametric sweep in [[EM.Terrano]], a tremendous amount of data may be generated. [[EM.Terrano ]] only stores the '''Received Power''', '''Path Loss''' and '''SNR''' of the selected receiver

[[EM.Terrano]]'s SBR solver uses a method known as Geometrical Optics (GO) in conjunction with the Uniform Theory of Diffraction (UTD) to trace the rays from their originating point at the source to the individual receiver locations. Rays may hit obstructing objects on their way and get reflected, diffracted or transmitted. [[EM.Terrano]]'s SBR solver can only handle diffraction off linear edges and reflection from and transmission through planar interfaces. When an incident ray hits the surface of the obstructing object, a local planar surface assumption is made at the specular point. The assumptions of linear edges and planar facets are valid in in the case of a scene with cubic buildings and a flat global ground.

In many practical scenarios, however, your buildings may have curved surfaces, or the terrain may be irregular. [[EM.Terrano ]] allows you to draw any type of surface or solid geometric objects such as cylinders, cones, etc. under impenetrable and penetrable surface groups or penetrable volumes. [[EM.Terrano]]'s mesh generator creates a triangular surface mesh of all the objects in your propagation scene, which is called a facet mesh. Even the walls of cubic buildings are meshed using triangular cells. This enables [[EM.Terrano ]] to properly discretize composite buildings made of conjoined cubic objects.

Unlike [[EM.Cube]]'s other computational modules, the density or resolution of [[EM.Terrano]]'s surface mesh does not depend on the operating frequency and is not expressed in terms of the wavelength. The sole purpose of [[EM.Terrano]]'s facet mesh is to discretize curved and irregular scatterers into flat facets and linear edges. Therefore, geometrical fidelity is the only criterion for the quality of a facet mesh. It is important to note that discretizing smooth objects using a triangular surface mesh typically creates a large number of small edges among the facets that are simply mesh artifacts and should not be considered as diffracting edges. For example, each rectangular face of a cubic building is subdivided into four triangles along the two diagonals. The four internal edges lying inside the face are obviously not diffracting edges. A lot of subtleties like these must be taken into account by the SBR solver to run accurate and computationally efficient simulations.

You can view and examine the discretized version of your scene objects as they are sent to the SBR simulation engine. You can adjust the mesh resolution and increase the geometric fidelity of discretization by creating more and finer triangular facets. On the other hand, you may want to reduce the mesh complexity and send to the SBR engine only a few coarse facets to model your buildings. The resolution of [[EM.Terrano]]'s facet mesh generator is controlled by the '''Mesh Cell Size''' parameter, which is expressed in project length units. The default mesh cell size of 100 units might be too large for non-flat objects. You may have to set a smaller mesh cell size in [[EM.Terrano]]'s Mesh Settings dialog, along with a lower curvature angle tolerance value to capture the curvature of your curved structures adequately.

[[Image:Info_icon.png|40px]] Click here to learn more about [[EM.Terrano]]'s '''[[Glossary of EM.Cube's Mesh Generators#Facet Mesh | Facet Mesh Generator]]'''.

Once you have set up your propagation scene in [[EM.Terrano ]] and have defined sources/transmitters and observables/receivers for your scene, you are ready to run a SBR ray tracing simulation. [[EM.Terrano ]] offers thee simulation modes:

You set the simulation mode in [[EM.Terrano]]'s simulation run dialog. A single-frequency analysis is a single-run simulation. The two other simulation modes in the above list are considered multi-run simulations. If you run a simulation without having defined any observables, no data will be generated at the end of the simulation. In multi-run simulation modes, certain parameters are varied and a collection of simulation data files are generated. At the end of a sweep simulation, you can graph the simulation results in EM.Grid or you can animate the 3D simulation data from the navigation tree.

{{Note| [[EM.Terrano]]'s frequency sweep simulations are very fast because the geometrical optics (ray tracing) part of the simulation is frequency-independent.}}

You can access [[EM.Terrano]]'s Simulation Run dialog by clicking the '''Run''' [[File:run_icon.png]] button of the '''Simulate Toolbar''' or by selecting '''Simulate &gt; Run...''' or using the keyboard shortcut {{key|Ctrl+R}}. When you click the {{key|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.

There are a number of SBR simulation settings that can be accessed and changed from the SBR Settings Dialog. To open this dialog, click the button labeled {{key|Settings}} on the right side of the '''Select Engine''' drop-down list in the Run Dialog. [[EM.Terrano]]'s SBR simulation engine allows you to separate the physical effects that are calculated during a ray tracing process. You can selectively enable or disable '''Reflection/Transmission''' and '''Edge Diffraction''' in the "Ray-Block Interactions" section of this dialog. By default, the reflection, transmission and edge diffraction effects are enabled and the terrain diffraction effects are disabled. Separating these effects sometimes help you better analyze your propagation scene and understand the impact of various blocks in the scene.

[[EM.Terrano ]] allows a finite number of ray bounces for each original ray emanating from a transmitter. This is very important in situations that may involve resonance effects where rays get trapped among multiple surfaces and may bounce back and forth indefinitely. This is set using the box labeled &quot;'''Max No. Ray Bounces'''&quot;, which has a default value of 10. Note that the maximum number of ray bounces directly affects the computation time as well as the size of output simulation data files. This can become critical for indoor propagation scenes, where most of the rays undergo a large number of reflections. Two other parameters control the diffraction computations: '''Max Wedge Angle''' in degrees and '''Min Edge Length''' in project units. The maximum wedge angle is the angle between two conjoined facets that is considered to make them almost flat or coplanar with no diffraction effect. The default value of the maximum wedge angle is 170&deg;. The minimum edge length is size of the common edge between two conjoined facets that is considered as a mesh artifact and not a real diffracting edge. The default value of the minimum edge length is 5 project units.

[[EM.Terrano]]'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.

When you run either a frequency sweep or a parametric sweep simulation in [[EM.Terrano]], you 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 '''&quot;Create Mean and Standard Deviation Coverage Maps&quot;'''. 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 show the statistics with respect to the frequency or other sweep variable sets at each point in the site. 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.

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