Comments on: SPLAT! RF Signal Propagation, Loss, And Terrain Analysis Tool

By: VE3NCQ

VE3NCQ — Tue, 15 May 2012 11:40:03 +0000

An .scm file is created for each site automatically to key the contour colours. Normally these are default values, but you can edit them in many ways. Check the help file for more information. As for a file of grid data, there is indeed one created, which is the actual image itself. It is essentially a grid where every pixel represents the computed value converted to a colour. There is no way to further refine this. However, any decent photo editor should allow you to measure that value at any pixel.

By: Larry

Larry — Sat, 12 May 2012 19:54:42 +0000

i am not sure i understand your response. with a -plo element i can get either path loss or received power, but the problem is that the output file is a line segment not a contour of data. How do it get a contour data set out? I am looking for a grid of data which must be generated to produce the .ppm file. also, what is a .scm file?

Thanks

By: VE3NCQ

VE3NCQ — Thu, 10 May 2012 13:14:58 +0000

I will have to try this out when I get a moment since I have limited experience using that file. The text file should be huge if everything is working right, but not all analysis generate one. I’m not sure if you are using the GUI or command line, but it seems to me that the GUI doesn’t do the huge file since its use is so specialized. The GUI does save a copy of the command line it generates, so it can be easily modified and run from a DOS prompt.

The file with received power and path loss is a separate text file called Site Report.

If you’re trying to limit the contour data, try editing the .scm files for the QTH, using colours only where you want to see the data. You can use this option to limit the colours displayed, and there is an option to limit the entire analysis out to a specific signal level. I’ve done this to display two colours for only my city grade and Grade A contour.

By: VE3NCQ

VE3NCQ — Thu, 10 May 2012 12:59:35 +0000

There is a sample file at www.ve3ncq.ca/pub/WVPY-dBm.kml. Be warned that the image files are very large and may take some time to download, but you should be able to right-click the file and Save As to download just the .kml file. Then you can pull it into an editor and see how I did it.

By: VE3NCQ

VE3NCQ — Thu, 10 May 2012 12:36:32 +0000

You can create a .dat file in any plain text editor. It can’t be a word processor. Notepad works fine, but you have to save the name in quotes or else Notepad tries to add .txt to the name. Another program is the Bluefish Editor, which can do text files as well as C, PHP, HTML, KML, and other program source code. It’s is available freely from http://www.bennewitz.com/bluefish/stable/binaries/win32/Bluefish-2.2.1-setup.exe. Whatever you use, it must be plain text and not formatted in any way. The format is like this:

Milton, 43.513861, 79.884114
Hamilton, 43.257823, 79.869113
Burlington, 43.324583, 79.797406
Oakville, 43.467739, 79.691624

You can get the coordinates using Google Earth. SPLAT can create a .kml file for use in Google Earth. You can edit the .kml file in Bluefish (it’s not too hard to figure out what’s going on). Using a straight overlay, you have access to all the Google Earth place names, roads, and terrain so you don’t have to worry about creating external files.

One trick that works for me is to check “force terrain to white” in SPLAT, take the huge SPLAT .ppm file into GIMP or some other photo editor, do a colour search to change white into transparent, save the image as a .png file, then edit the .kml file to change the overlay file name to .png. This gives you a Google Earth overlay of just your plot. When doing a huge analysis in HD of our high-powered TV transmitters, the .ppm files were too big for Google Earth. Converting them to PNG helped, but by splitting the huge image into tiles of separate files carefully cropped (strips of 3600 pixels high), and editing the overlay in the .kml file to make the coordinates match, I was able to get everything to display.

Austin

By: Larry

Larry — Wed, 09 May 2012 20:40:27 +0000

i am back again with another question. i am trying to get a text file out with data to do a contour analysis. since i am using the Windows version i get a text file out using the -plo selection. this file should contain received power or path loss depending on the options selected. But, instead of a contour of data, i get just a single line. is there a way to get a contour of data out covering a defined region?

thanks

By: repeater builder

repeater builder — Wed, 09 May 2012 17:49:59 +0000

I am working with creating some repeater maps. One thing I am unsure on the process to create a Data File, ie cities.dat

I understand the concept of
City, Lat, Long
City, Lat, Long
City, Lat, Long

What is the preferred program to create a landmark dat file, the documentation outlines to use a text editor. When I use Windows Notepad to open a (.dat) file the values do not look valid, the values look to be exponent values and numerous, it does not look like Lat-Lon values. Secondly, can I create a dat file with Notepad, if so which format should I save it? Any other suggestions of advice?

Thanks.

By: VE3NCQ

VE3NCQ — Sun, 06 May 2012 16:52:55 +0000

Not all flavours of analysis produce the huge path loss file, but that file is capable of being edited and run through SPLAT instead of using the original terrain data. Other than that, there is no other access to raw data unless you dig into the source code to produce additional output.

By: Larry

Larry — Sat, 05 May 2012 20:23:24 +0000

Thanks, that approach for free space worked. I have another question: is it possible to get access to more of the raw data beyond the pathloss file? I would like to do some different processing & plotting but am confined by the .png. Your help is appreciated.

By: VE3NCQ

VE3NCQ — Sat, 05 May 2012 00:45:59 +0000

You can do that, but you’ll wind up with straight path loss and perhaps an antenna pattern. If terrain files are missing, SPLAT assumes sea level. If you have terrain files, just set your QTH to coordinates that don’t have files.