== Working with SBR Simulation Data ==
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=== EM.Terrano's Output Simulation Data ===
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At the end of an SBR simulation, all the polarimetric rays emanating from the transmitter(s) or other sources that are received by the individual receivers are computed, collected, sorted and saved. From the ray data, the total electric field at the location of receivers as well as the received power are computed. The ray data include the field components of each ray, the ray's elevation and azimuth angles of departure and arrival (departure from the transmitter location and arrival at the receiver location), and time delay of the received ray with respect to the transmitter. If you specify the temperature, noise figure levels and transmission line losses in the definition of the receiver sets, the noise power level and signal-to-noise ratios (SNR) at each receiver are also calculated. If you define a field sensor, or a far field observable, or a Huygens surface for your project, your output simulation data will include near-field distribution maps, far field radiation patterns or Huygens surface data files, respectively.
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=== Visualizing Field & Received Power Coverage Maps ===
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As an asymptotic EM simulator, EM.Terrano computes the polarimetric electric field at every receiver location including amplitude and phase of all three X, Y, Z field components as well as the total field magnitude. In wireless propagation modeling for communication system applications, the received power at the receiver location is more important than the field values. Wireless coverage maps commonly refer to the received power levels at different locations in a given site. In order to compute the received power, you need three pieces of information:
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* '''Total Transmitted Power (EIRP)''': This requires knowledge of the baseband signal power, the transmitter chain parameters, the transmission characteristics of the transmission line connecting the transmitter circuit to the transmitting antenna and the radiation characteristics of the transmitting antenna.
* '''Channel Path Loss''': This is computed through SBR simulation.
* '''Receiver Properties''': This includes the radiation characteristics of the receiving antenna, the transmission characteristics of the transmission line connecting the receiving antenna to the receiver circuit and the receiver chain parameters.
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The received power P<sub>r</sub> in dBm is found from the following equation:
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<math> P_r [dBm] = P_t [dBm] + G_{TC} + G_{TA} - PL + G_{RA} + G_{RC} </math>
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where P<sub>t</sub> is the baseband signal power in dBm at the transmitter, G<sub>TC</sub> and G<sub>RC</sub> are the total transmitter and receiver chain gains in dB, respectively, G<sub>TA</sub> and G<sub>RA</sub> 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.
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EM.Terrano's transmitters always require a radiation pattern file unless you use a short dipole source to excite your structure. On the other hand, EM.Terrano's default receivers are assumed to be isotropic radiators. Although isotropic radiators do not exist as actual physical antennas, they make convenient and useful theoretical observables for the purpose of power coverage map calculations. EM.Terrano's isotropic receiving radiators are assumed to be polarization-matched to the incoming rays. As such, they have a unity gain and do not exhibit any polarization mismatch losses.
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At the end of an SBR simulation, you can visualize the field maps and receiver power coverage map of your receiver sets. A coverage map shows the total '''Received Power''' by each of the receivers and is visualized as a color-coded intensity plot. Under each receiver set node in the navigation tree, a total of seven field maps together with a received power coverage map are added. The field maps include amplitude and phase plots for the three X, Y, Z field components plus a total electric field plot. To display a field or coverage map, simply click on its entry in the navigation tree. The 3D plot appears in the Main Window overlaid on your propagation scene. A legend box on the right shows the color scale and units (dB). The 3D coverage maps are displayed as horizontal confetti above the receivers. You can change the appearance of the receivers and maps from the property dialog of the receiver set. You can further customize the settings of the 3D field and coverage plots.
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[[Image:Info_icon.png|40px]] Click here to learn more about '''[[Data_Visualization_and_Processing#Visualizing_3D_Near-Field_Maps | Visualizing 3D Near-Field Maps]]'''.
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At the end of a frequency sweep or parametric sweep SBR simulation, as many coverage maps as the number of sweep variable samples are generated and added to the navigation tree. In this case the additional seven field maps are saved to avoid a cluttered navigation tree. You can click on each of the coverage maps corresponding to each of the variable samples and visualize it in the project workspace. You can also animate the coverage maps on the navigation tree.
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[[Image:Info_icon.png|40px]] Click here to learn more about '''[[Data_Visualization_and_Processing#3D_Near_.26_Far_Field_Animation | Animating 3D Near-Field Maps]]'''.
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<table>
<tr>
<td> [[Image:prop_run11_tn.png|thumb|550px|Received power coverage map of an urban propagation scene.]] </td>
</tr>
<tr>
<td> [[Image:prop_run12_tn.png|thumb|550px|Total electric field map of an urban propagation scene.]] </td>
</tr>
</table>
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=== Calculating the SNR & Visualizing Connectivity Maps===
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If you specify the noise-related [[parameters]] of your receiver set, the signal-to-noise ratios (SNR) is calculated at each receiver location: SNR = P<sub>r</sub> - P<sub>n</sub>, where P<sub>n</sub> is the noise power level in dB. When planning, designing and deploying a communication system between points A and B, the link is considered to be closes and a connection established if the received signal power at the location of the receiver is above the noise power level by a certain threshold. In other words, the SNR at the receiver must be greater than a certain specified minimum SNR level. You specify (SNR)<sub>min</sub> ss part of the definition of receiver chain in the Receiver Set dialog. In the "Visualization Options" section of this dialog, you can also check the check box labeled '''Generate Connectivity Map'''. This is a binary-level black-and-white map that displays connected receivers in white and disconnected receivers in black. At the end of an SBR simulation, the computed SNR is displayed in the Receiver Set dialog for the selected receiver. The connectivity map is generated and added to the navigation tree underneath the received power coverage map node.
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<table>
<tr>
<td> [[Image:PROP15A.png|thumb|550px|The connectivity map of an urban propagation scene with minimum SNR level set to 25dB.]] </td>
</tr>
</table>
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=== Visualizing the Rays in the Scene ===
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[[Image:PROP12B.png|thumb|420px|EM.Terrano's Ray Data dialog.]]
At the end of a SBR simulation, each receiver receives a number of rays. Some receivers may not receive any rays at all. You can visualize all the rays received by a certain receiver from the active transmitter of the scene. To do this, right click the '''Receivers''' item of the Navigation Tree. From the context menu select '''Show Received Rays'''. All the rays received by the currently selected receiver of the scene are displayed in the scene. The rays are identified by labels, are ordered by their power and have different colors for better visualization. You can display the rays for only one receiver at a time. The receiver set property dialog has a list of all the individual receivers belonging to that set. To display the rays received by another receiver, you have to change the '''Selected Receiver''' in the receiver set's property dialog. If you keep the mouse focus on this dropdown list and roll your mouse scroll wheel, you can scan the selected receivers and move the rays from one receiver to the next in the list. To remove the visualized rays from the scene, right click the Receivers item of the Navigation Tree again and from the context menu select '''Hide Received Rays'''.
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You can also view the ray parameters by opening the property dialog of a receiver set. By default, the first receiver of the set is always selected. You can select any other receiver from the drop-down list labeled '''Selected Receiver'''. If you click the button labeled '''Show Ray Data''', a new dialog opens up with a table that contains all the received rays at the selected receiver and their parameters:
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* Delay is the total time delay that a ray experiences travelling from the transmitter to the receiver after all the reflections, transmissions and diffractions and is expressed in nanoseconds.
* Ray Field is the received electric field at the receiver location due to a specific ray and is given in dBV/m.
* Ray Power is the received power at the receiver due to a specific ray and is given in dBm.
* Angles of Arrival are the θ and φ angles of the incoming ray at the local spherical coordinate system of the receiver.
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The Ray Data Dialog also shows the '''Total Received Power''' in dBm and '''Total Received Field''' in dBV/m due to all the rays received by the receiver. You can sort the rays based on their delay, field, power, etc. To do so, simply click on the grey column label in the table to sort the rays in ascending order based on the selected parameter. You can also select any ray by clicking on its '''ID''' and highlighting its row in the table. In that case, the selected rays is highlighted in the Project Workspace and all the other rays become thin (faded).
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{{Note|All the received rays are summed up coherently in a vectorial manner at the receiver location.}}
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<table>
<tr>
<td> [[Image:prop_run5_tn.png|thumb|550px|Visualization of received rays at the location of the selected receiver.]] </td>
</tr>
<tr>
<td> [[Image:prop_run6_tn.png|thumb|550px|Analyzing a selected ray from the ray data dialog.]] </td>
</tr>
</table>
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=== Output Data Files ===
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[[Image:prop_run8_tn.png|thumb|800px|A typical SBR output data file.]]
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.
At the end of an SBR simulation, the results are written into a main output data file with the reserved name of SBR_Results.RTOUT. This file has the following format:
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Each receiver line has the following information:
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* Receiver ID
* Receiver X, Y, Z coordinates
* Total received power in dBm
* Total number of received rays
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Each rays line received by a receiver has the following information:
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* Ray Index
* Delay in nsec
* θ and φ Angles of Arrival in deg
* θ and φ Angles of Departure in deg
* Real and imaginary parts of the three E<sub>x</sub>, E<sub>y</sub>, E<sub>z</sub> components
* Number of ray hit points
* Coordinates of individual hit points
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The angles of arrival are the θ and φ angles of a received ray measured in degrees and are referenced in the local spherical coordinate systems centered at the location of the receiver. The angles of departure for a received ray are the θ and φ angles of the originating transmitter ray, measured in degrees and referenced in the local spherical coordinate systems centered at the location of the active transmitter, which eventually arrives at the receiver. The total time delay is measured in nanoseconds between t = 0 nsec at the time of launch from the transmitter location till being received at the receiver location.
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=== Plotting Other Simulation Results ===
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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}}.
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The available data files in the "2D Data Files" tab of Data Manger include:
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* '''Path Loss''': The channel path loss is defined as PL = P<sub>r</sub> - EIRP. The path loss data are stored in a file called "SBR_receiver_set_name_PATHLOSS.DAT" as a function of the receiver index. The path loss data make sense only if your receiver set has the default isotropic radiator.
* '''Power Delay Profile''': The delays of the individual rays received by the selected receiver with respect to the transmitter are expressed in ns and tabulated together with the power of each ray in the file "SBR_receiver_set_name_DELAY.DAT". You can plot these data from the Data Manager as a bar chart called the power delay profile. The bars indeed correspond to the difference between the ray power in dBm and the minimum power threshold level in dBm, which makes them a positive quantity.
* '''Angles of Arrival''': These are the Theta and Phi angles of the individual rays received by the selected receiver and saved to the files "SBR_receiver_set_name_ThetaARRIVAL.ANG" and "SBR_receiver_set_name_PhiARRIVAL.ANG". You can plot them in the Data Manager in polar stem charts.
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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
in ASCII data files called "PREC_i.DAT", "PL_i.DAT" and "SNR_i.DAT", where is the index of the receiver set in your scene. These quantities are tabulated vs. the sweep variable's samples. You can plot these files in EM.Grid.
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[[Image:Info_icon.png|40px]] Click here to learn more about working with data filed and plotting graphs in [[EM.Cube]]'s '''[[Data_Visualization_and_Processing#Working_with_Data_Files_in_Data_Manager| Data Manager]]'''.
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<table>
<tr>
<td> [[Image:PROP20E.png|thumb|350px|Cartesian graph of path loss.]] </td>
<td> [[Image:PROP20F.png|thumb|350px|Bar graph of power delay profile.]] </td>
</tr>
<tr>
<td> [[Image:PROP20G.png|thumb|350px|Polar stem graph of Phi angle of arrival.]] </td>
<td> [[Image:PROP20H.png|thumb|350px|Polar stem graph of Theta angle of arrival.]] </td>
</tr>
</table>
=== Statistical Analysis of Propagation Scene ===