Dynmap: The dynamic Noise Map
A noise map generated with CadnaA can now be updated dynamically using measured data.
The most important application of this feature is the direct coupling to automatic monitoring systems installed along main roads or in the vicinity of industrial plants or airports. The measured data is automatically transferred to the CadnaA-PC to update the noise map and to display the result in a bitmap file.
This operation is extremely fast as no further recalculation of the sound propagation is required to adapt the noise map to the measured data. Each monitoring station is installed in such kind that the dominating sound pressure level is measured from the allocated sound source only.
For each of the monitored noise source and for the remaining noise sources together noise maps with the whole urban area have to be calculated and saved separately. By 30 monitoring systems have to be calculated 31 noise maps in the run up.
CadnaA samples the measured data, adds the resulting difference with respect to the original grid data to the total noise map and calculates by energetic summation of all updated noise maps the new total noise map.
The updating process can either be based on measured sound level data or e.g. on automatically registered traffic count data or other source parameters.
With sound level data provided by the monitoring system CadnaA - e.g. hourly mean level Leq - enables to display up-to-date information by a noise map referenced to e.g. the preceding hour. Further CadnaA-features allow to present noise maps as public information via the Internet.
Depending on the configuration, noise maps can be generated even for past time periods. Whether the Lden of the preceding year or the mean sound level on all Sundays of the last month shall be displayed, by applying the dynamic noise map DYNMAP of CadnaA this is performed automatically, with the well-known CadnaA-precision and – if required – fully integrated into a GIS-system. DYNMAP is not an extra option of CadnaA but integrated in the software itself.
Procedure
Create or import your project file with all desired noise sources, buildings etc.
Determine the position of the monitoring systems for all dominating noise sources. Mark the positions in the CadnaA file with e.g. a receiver point or text frame.
For all monitoring systems determine the dominating noise sources which emission data have to be reassigned to the altered value. To do so just create groups in CadnaA. All noise sources which are assigned to a monitoring system get the same ID, e.g. for the monitoring system one the ID V01, for the monitoring system two V02 etc.
Calculate a separate noise map for each of these noise groups and save this map with
Calculate a noise map with all not monitored remaining noise sources. For that deactivate all other monitored groups of noise sources in this variant. Save this noise map, too, e.g. with the filename RST.CNR.
Calculate a overall noise map with all noise sources activated or sum all separate calculated noise maps via the
Example
Path: Examples\ProjectOrg\ DYNMAP
Furthermore, the files from the download directory are required to achieve the dynamic noise mapping.
URSVAL.INI
URSVAL.INI (a Windows-INI-file) in which the deviation is written from the primary value to the corresponding measured value of the monitoring system. It makes sense to write a user-defined macro or a little program which analyzed the measured data of the monitoring system and which writes the deviation into this INI-file.
Example
[ursval]
val01=0
val02=8
val03=0
val04=0
The string val_n_= is mandatory and is the alias name of one of the monitoring system in the project file together with the deviation from the primary measured value (val02=8 means that the measured value is increased by 8 dB from this monitoring system). n is a serial numbering starting with 01. The corresponding noise map, e.g. V02.CNR, will be updated with this new value via grid arithmetic. Insert as many rows as monitoring systems exist which you like to evaluate. If you have ten monitoring systems you should have ten rows with val_n_ between val01 and val10.
MEAS.CNM
MEAS.CNM is a CadnaA macro which can be adjusted by the user itself corresponding to his project. It opens the CadnaA file with the existing noise map, makes the grid arithmetic taken into account the deviation of the measured values form the URSVAL.INI and creates a Bitmap-file (WEB-Bitmap) automatically form the updated noise map. The CadnaA file MEAS.CNA and in the run-up separately saved noise maps (*.cnr) will not be changed.These files remain untouched as "Mother-files" and are only accounted for the calculation of the noise maps to be updated.
Example
(LoadFile,meas.cna)
(GridCalc, "r1", rst.cnr)
(GridCalc, "r0 ++ r1+usrval(1)", v01.cnr)
(GridCalc, "r0 ++ r1+usrval(2)", v02.cnr)
(GridCalc, "r0 ++ r1+usrval(3)", v03.cnr)
(GridCalc, "r0 ++ r1+usrval(4)", v04.cnr)
(ExportFile, meas.bmp, WebBmp, web, 10000, 1)
(QuitAtOnce)
General: #(GridCalc, Ausdruck, r1)
The expression #(ExportFile, meas.bmp, WebBmp, web, 10000, 1) exports a bitmap file saved with the file name "meas.bmp" in WebBmp format with the updated noise map including only the section of the noise map named web, scaled 1:10000 of the resolution step 1. This file would be now applicable for subsequent processing for the Internet. Fore more information about Web-Bitmaps see Web-Bitmaps in the CadnaA reference manual.
The strings r0, r1, r2 ...r6 corresponds with the dialog
Dialog Menu Grid|Arithmetics
In our example after the first line is executed the noise map RST.CNR (without noise sources which are monitored by a monitoring system) will be the current grid and can therefore be referenced with the string r0.
In the second row of the macro to the current grid r0 is added the noise map v01.cnr energetically and the correction value from the URSVAL.INI (val01=) arithmetically. After this operation this updated grid is the current grid r0 etc.
This macro must be adjusted with the corresponding user-defined grid names *.cnr.
MEAS.BAT
The MEAS.BAT starts CadnaA and executes the CadnaA macro MEAS.CNM.
Example
Environment Variable
In case the program file "cna64.exe" is not installed in the default directory (C:\Program Files\Datakustik\CadnaA64) an environment variable CNA_PATH without final back slash (\) has to be set (e.g. C:\Program Files\Datakustik\CadnaA64\cna64.exe). For more information on how to set an environment variable please see the WINDOWS documentation or search on the Internet.
Example DYNMAP
The following mentioned example files in the directory Examples|18_ProjectOrg|DYNMAP. Copy all files to the same directory on your PC.
- Open the CadnaA file MEAS.CNA. A noise map for all roads of a small city with four monitoring systems P1 - P4 is displayed.
In menu Tables|Groups you can see the existing variants. The variants are created in such a way that the variant V01 activates the roads which are monitored by the monitoring systems P1, V02 activates the roads which are monitored by the monitoring systems P2 etc. The variant RST switched off all roads which are monitored by a monitoring system. For all these variants the noise maps have been calculated separately with the whole calculation area and their grid have been saved with a corresponding name like V01.cnr, V02.cnr etc. Thus for four monitoring systems five noise maps have been created.
Because we don't have a monitoring system in our example we change the correction values for the measured data manually in the file USRVAL.INI.
- Open this file URSVAL.INI with an editor, change the values behind the equals sign and save the file again with the same name.
- Now execute the MEAS.BAT with a double-click on its file name. This starts CadnaA, opens the file MEAS.CNA, makes the grid arithmetic and saved the result as bitmap file MEAS.BMP. This file can be opened with a arbitrary imaging-editing software.
Example DYNMAP with Excel
Another example shows the EXCEL file MEAS.XLS. The EXCEL file already contains a macro which can be executed with a click on the button CALCULATE. This would write the correction values in the above table in the file USRVAL.INI automatically, makes the grid arithmetic automatically we described above and would save the result in a bitmap file which is displayed at once in the EXCEL file.
- For example, increase the value in the column Meas.Value (yellow colored) for the monitoring system 2 (Point 2) to 77 and execute the macro.
Look for the noise map in the vicinity of the road at the monitoring point 2. Note that everything is executed automatically, ending up with displaying the updated noise map.