QRP Propagation Simulation: One Day on All Ham Bands

Below a series of images for the band conditions today using the parameters of my QRP station.
The script used for the simulation can be found here:

HF Propagation Simulation: Influence of TX Power

Here I show some contour plots (circuit reliability) of my simulation results on the 20m band at different times (day & night) using 1 Watt and 99 Watt. The simulation parameters are mentioned elsewhere.
1 Watt – 12h
1 Watt – 23h
99 Watt – 12h
99 Watt – 23h

HF Propagation Simulation: Variation of Time on all QRP Frequencies

In this post I show some video results of my Voacap simulations for HF propagation: the time has been varied (0-23h).

Simulation Parameters

  • Antenna: isotrope
  • Mode: cw (required SNR for circuit reliability calculation: 24 dB)
  • Power: 50W
  • Transmitter location: JO40DA
  • Month: July
  • SSN: 72.8
  • Frequencies: QRP frequencies on all ham bands…

3.6 MHz

SNR (dB)
Circuit Reliability (%)

7.0 MHz

SNR (dB)
Circuit Reliability (%)

10.1 MHz

SNR (dB)
Circuit Reliability (%)

14.1 MHz

SNR (dB)
Circuit Reliability (%)

18.1 MHz

SNR (dB)
Circuit Reliability (%)

21.1 MHz

SNR (dB)
Circuit Reliability (%)

24.1 MHz

SNR (dB)
Circuit Reliability (%)

28.1 MHz

SNR (dB)
Circuit Reliability (%)

HF Propagation: Variation of the Frequency

In the following post I show some visual results of my Voacap simulations. The visualization has been done using some python and shell scripting.

Simulation Parameters

  • Antenna: isotrope
  • Mode: cw (required SNR for circuit reliability calculation: 24 dB)
  • Power: 50W
  • Transmitter location: JO40DA
  • Month: July
  • SSN:72.8
  • Time (UTC): 12h (=day) and 23h (=night)

Night Time – HF Propagates Nicely

SNR (dB)
Circuit Reliability (%)

Day – We have Damping

SNR (dB)
Circuit Reliability (%)

Installation of pythonProp under Debian

Example Area Calculation

In this article I describe how to install pythonProp under Debian (squeeze) linux.


Installing Voacapl

Follow the instructions given in this article.

Preparing Python

In the first step we prepare the build environment:

apt-get install libgeos-dev 

apt-get build-dep python-matplotlib

Building Basemap

Now we can download and install the basemap toolkit – it is not included in Debian (squeeze):
wget http://sourceforge.net/projects/matplotlib/files/matplotlib-toolkits/basemap-1.0.3/basemap-1.0.3.tar.gz
tar xzf basemap-1.0.3.tar.gz
cd basemap-1.0.3
sudo python setup.py sdist

Building Matplotlib 

As the matplotlib version supplied with Debian (squeeze) does not work, we download and install the matplotlib manually: 
wget http://sourceforge.net/projects/matplotlib/files/matplotlib/matplotlib-1.0/matplotlib-1.0.0.tar.gz
tar xzf matplotlib-1.0.0.tar.gz 
cd matplotlib-1.0.0/
python setup.py build
sudo python setup.py install

Installing pythonProp

Now we can install pythonProp manually:
tar xzf pythonprop-0.10.tar.gz
cd pythonprop-0.10
sudo make install
To see whether everything is ok, run


  1. pythonProp (HZ1JW)

Installation of VOACAP under OSX

Voacap is a tool for “HF Propagation Prediction and Ionospheric Communications Analysis” (1). In the following article I describe the steps to take in order to install the software under OSX. 


Build & Installation of Voacap

For the installation of the voacap commandline tools you can follow the steps mentioned in (2). Nevertheless I show the essential commands here:
wget http://www.qsl.net/hz1jw/voacapl/downloads/voacapl-0.5.8.tar.gz
tar xzf voacapl-0.5.8.tar.gz 
cd voacapl-0.5.8
sudo make install

Copy the Basic Configuration & Example Files

If you are new to voacap it is useful to start with some example files. Voacap expects them in its standard directory ~/itshfbc. The files can be copied manually:
cp -rv /usr/local/share/voacapl/itshfbc ~/

Testing the Installation 

cd ~/itshfbc

First test:
voacapl -s ~/itshfbc/ voacapx.dat
No output on screen? <= Ok 🙂
Something should be in this file:
cat run/voacapx.out 

Our second test is an area coverage analysis:

voacapl -s ~/itshfbc/ area calc default/default.voa
cat areadata/default/default.vg1 

Further Reading

  1. voacap.com
  2. OSX Installation Instructions
  3. What is Voacap trying to tell me? (N6BV)

Lazy VOACAP Analysis

If you want to save your time by not installing voacap on your computer, you still can use the online tool for coverage analysis (voacap.com). You can even automate this using a small shell script to build a PDF file with your HF propagation simulation.

Please note: The following script is provided for educational purpose only.


  • ImageMagick
  • wget


tt=$(date -u +”%Y %m %H”)
year=$(echo $tt | awk ‘{print$1}’)
month=$(echo $tt | awk ‘{print$2}’)
time=$(echo $tt | awk ‘{print$3}’)
txmode=24 #24=cw 38=ssb 49=am
rxantenna=d10m.ant #txantenna=isotrope.ant
_get_txband ()
 echo $filename
 echo $filename>&2
 test -e $filename && return
 wget -k -O $tmp “http://www.voacap.com/area.php?year=$year&month=$month&time=$time&TDX=9999&txname=$txname&txlat=$txlat&txlon=$txlon&txantenna=$txantenna&txpower=$txpower&txmode=$txmode&es=noes&band=$txband&path=Short&rxantenna=$rxantenna&#8221; 2>/dev/null
 img_url=$(cat $tmp | grep img |sed ‘s/.*src=”//;s/”.*//g’)
 wget -O $filename $img_url 2>/dev/null
 rm $tmp
# Some example loops for data extraction
_loop_outdoor ()
 txpower=0.005 #kW
 for time in 0 2 4 6 8 10 12 14 16 18 20 22; do
  for txband in 7.030 10.116 14.060; do #MHz
   files=$files” “$(_get_txband)
_loop_shack ()
 for txpower in 0.005 0.010 0.050; do #kW
  for txband in 3.560 7.030 10.116 14.060 18.086 21.060 24.906 28.060; do #MHz
   files=$files” “$(_get_txband)
pdfname=”$txname-“$(echo $tt |sed ‘s/ /-/g’)”.pdf”
echo convert $(echo $files) $pdfname