# WSPR Statistics

## Contents

One of my interests is looking at data, representing it and looking for trends. With WSPR the data it provides is great for doing looking at trends to do with the propagation of radio waves. Here, during the good HF conditions experienced over November 2011 I left WSPR receiving constantly as I often do. The purpose being to collect enough data to enable me to observe the trends in propagation.

You may also be interested in my time-lapse videos of WSPR on YouTube: TimeLapse WSPR Reception and TimeLapse WSPR Map

# Time of Day

In radio communications, especially my hobby, Ham Radio, the aim of the game is to get your signal to go as far as possible. Signal propagation is influenced by layers of the Earth's atmosphere, amongst other factors, which change throughout the day. These first plots aim to show how the distance of communication changes with time of day. These results have been aggregated over time (6 weeks for 30 metres, 1 week for 10 metres), and then I have plotted using gunplot.

As I had expected, distance is normally distributed around mid day - this can be seen from the bottom histogram plots. The first two rows show the raw plots of distance (top row) and received signal strength (middle row). The raw distance plots show many points where distance is very low, and these are uniformly distributed in time - these, I suspect, are from ground-wave radiation. Ground-wave radiation occurs when a receiver and a transmitter close together (hence the low distance); the receiver hears the transmitted signal without any reflections from the Earth's atmospheric layers and is therefore unaffected by time.

# Transmitter Power

The next thing I was curious to see what how did the transmitter power effect the distances workable? The first two plots show the raw data, linear transmitter power (in milliwatts) against distance (in kilometres). The power is quantised in steps by the WSPR program and set in dB. This was simply converted to milliwatts by the formula:

$P_{mW} = 10^{\frac{P_{dB}}{10}}$

There were some stations using a transmitter power of over 20 watts (20,000 mW), but these were removed, the largest majority of persons were using the displayed range.