Predicting RF Coverage and Link Performance

Calculating RF Links and coverage plots must take many influencing factors into consideration including, but not limited to:

* Propagation and Absorption
* Power output
* Antenna gains / patterns
* Topography and obstructions
* Receiver sensitivity
* Feedline losses

Tools

Radio Mobile

Radio Mobile is a freeware windows software application written by VE2DBE. It is available on the web here. This program has a learning curve but the results are very rewarding. Radio Mobile can take all of the above mentioned radio link & coverage variables into effect and produce coverage maps, and link calculations. RM supports multiple topography data formats with SRTM being the most convenient.

Radio Mobile can be found here
A tutorial can be found here.

Modeling Data

SRTM Data

The Shuttle Radar Topography Mission (SRTM) obtained elevation data on a near-global scale to generate the most complete high-resolution digital topographic database of Earth. SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle Endeavour during an 11-day mission in February of 2000. This topographical data can be used directly by some software.

SRTM Data Sources

After substantial editing efforts by the National Geospatial Intelligence Agency, NASA released Version 2 of their SRTM data. It is referred to as the "finished" version. Some incomplete data still remains but is highly usable.

The resolution of the data is measured in arc-seconds with the lower number being greater. Most of the world has SRTM3 (3 arc-second) data while SRTM1 or 1 arc-second data is only available for select regions. The map showing the 1 arc second regions is available here.

SRTM V2 3 arc-second

ftp://e0srp01u.ecs.nasa.gov/srtm/version2/SRTM3/

SRTM V2 1 arc-second

Locals Note: 1 arc-second data covers at the most the lower half of Vancouver Island.

ftp://e0srp01u.ecs.nasa.gov/srtm/version2/SRTM1/

Longley Rice Modeling

http://lrcov.crc.ca/cov.php?lang=en

Misc Data

Typical Parameters

"Typical" 25W VHF Transmitter (Motorola CDM-1550-LS+)
Output Power: 25-45W (44-46.5 dBm)
Receive Sensitivity: 0.3uV/-117.5dB (0.23uV/-119.8 Typical)

Page Maintainer--
Matthew Currie VE7MJC