Using RadioMobile to evaluate Meteor Scatter DX-pedition sites
Recently good elevation data has become available free of charge for the Nordic countries and European Russia to the Urals. The data generated by the Space Shuttle only covered up to 60° N.
Coverage of the new data (areas below 60° N are all
available):
I recommend that you start by downloading the data
you need to your hard drive using a seperate FTP program, as
RadioMobile is not very
tolerant to errors in the download process. You do not need to unzip the
individual tiles (eg. N55E012.zip containing N55E012.hgt) - RadioMobile can do this on the fly.
The elevation data can be used together with the program RadioMobile to evaluate the take-off from a potential DX-pedition site. All what is required is Lat / Lon position data for the location. Such data can be found easily using Google maps. Use the position data to generate a Unit in RadioMobile.
Then generate a map of the location covering all elevations with an influence on the take-off. The pixel resolution of the map equals the resolution of elevation points. You should therefore not make the map geographical bigger than neccessary, and with as high pixel resolution as possible. The number of pixels determines the time it takes to make a map, so that puts a practical limitation to the number of pixels. I think 2000 * 2000 pixels and a map height of 50 km should do it in most cases. If the elevation points resolution becomes too small it might distort the local situation close to the selected site and influence the calculated Visual Horizon. The distortions due to local scaling can often be recognized in that they look more discrete with less detail (see 0 - 20° in the Visual Horizon figure below). The scaling is less of a problem in the case, where your site is at a local maximum (like the top of a hill).
Tick the box "Adjust units elevation" the first time you
draw the map.
Then use the function "visual horizon" to get an impression on the take-off
By clicking in the Visual Horizon graph you can determine the distance to the horizon in given direction. If you see red lines in the graph, your horizon lies beyond the generated map, and you should increase the map height. This is also valid if your horizon lies near the map boundaries (ie. 25km with 50km map height).
Follow this link to evaluate the MS possibilities from the QTH.
| RANGE (km) | ELEVATIONS | AZIMUTH OFFSETS (to Hotspots) |
| 500 | 18 | 21 |
| 600 | 15 | 18 |
| 700 | 13 | 16 |
| 800 | 11 | 15 (with a normal antenna beam direct, not to Hotspot) |
| 900 | 9 | 14 (with a normal antenna beam direct, not to Hotspot) |
| 1000 | 8 | 13 (with a normal antenna beam direct, not to Hotspot) |
| 1200 | 6 | 11 (with a normal antenna beam direct, not to Hotspot) |
| 1500 | 4 | 10 (with a normal antenna beam direct, not to Hotspot) |
| 1800 | 2 | 10 (with a normal antenna beam direct, not to Hotspot) |
| 2000 | 1 | 10 (with a normal antenna beam direct, not to Hotspot) |
| 2500 | 0 | 8 (with a normal antenna beam direct, not to Hotspot) |
What are hotspots ? - read part 2, section "Forward Scattering Geometry"
Use a close-in plot to get an idea of the local obstacles, and find the
optimal QTH. Also use the close-in plot to check, that you are at the right
place in the elevation data set. Small calibration errors could exist in both Goggle
maps and the elevation data.
You are always welcome to contact me if you have questions or need help.
