Height data can be obtained by various sources. The main source of height data is SRTM data from NASA. But also other sources of SRTM data can be configured.
The actual url of the source of DEM is configured in the file 'internet.dat'
As the world wide SRTM data set is (too)big it is preferred to make a preselection depending on the area in which you want to make the analysis.
Also you have to pay attention to the way in which the data is approached on the web. All SRTM data from NASA is accessed through FTP. This might be causing problems when behind a fire wall or proxy. When choosing 'other' as SRTM source yo can select web access (http).
More information about SRTM and how it is handled by Radio Mobile in 'Geodata > Background on DEM'
Selection of source.
Here you select the source of your data; Either you download is, or you download it and store it locally for faster access, or you use loacl data: select the method:
The path to the directory where you store the data wehn buffered. The [Browse] button will allow you to select a prior created directory.
The URL of the data on the web.
This is grayed-out when a sourec not Other is selected.