Introduction

The WSPR Beacon V53ARC was developed and built by Gernot Frauscher, OE1IFM (see picture). On his website www.oe1ifm.at in the menu “WSPR Beacon Project“, the setup and method of working of the system is explained in detail. The beacon was installed in Windhoek on Oct 16th 2009 by Gernot (OE1IFM), Clemens (OE1CSC), Karl-Heinz (V51KH), Sebastian (V51IG) and Wolfgang (V51WG). We would like to thank Gernot for giving us the opportunity to run and maintain the beacon and vertical antenna, by making it available to us.

What is WSPR?

WSPR is the name for a radio amateur digital mode and stands for “Weak Signal Propagation Reporter.” It is pronounced as ‚whisper’. This mode implements a protocol designed for probing potential propagation paths with low-power transmissions.

The WSPR signal has a very narrow bandwidth of 5.9 Hz. It only uses 1/500th of the space that a SSB signal would use. By using a special Fold-Algorithm, this mode reaches a redundancy of more than 10. This means that all the information that is sent will be transmitted more than ten times. The information is mixed sequentially and can be reconstructed even when a relative high percentage of the transmission is lost. Low data density and the small bandwidth contribute to increase a high safety of transmission. Thereby it is possible with low power, as low as 30dbm and with small antennas, to send information around the globe. The WSPR-Decoders are capable of receiving extremely weak signals down to a minimum of -32 dB SNR (1500 times weaker than the normal background noise).

How does WSPR work?

WSPR is a MFSK-Mode (Multi-Frequency-Shift-Keying). Four frequencies are switched by a special Fold-Algorithm developed by Joseph Taylor (K1JT). The bandwidth that WSPR uses is 5,9Hz and is compiled by the transmitted tones of 1497,8Hz, 1499,2Hz, 1500,7Hz and 1502,2Hz.

The actual transmitted information during a transmission is always 50 bits. This is why it’s possible to send only callsign, position and transmitting power. The redundance exceeding 10 brings a extreme high communication reliability.

WSPR-transmissions are being transmitted in 2 minute intervals. Receiver and transmitter must therefore be synchronised with an Internet time server. This synchronisation is best reached by way of GPS receivers. The WSPR transmitting cycle starts with every even minute. The first two seconds are being used to encode the signal. In the following 110.59 seconds, 162 channel symbols are transmitted. Each symbols lasts for 0.6827 seconds. This constitutes of a baud rate of 1.46 bits/second. In the remaining 7.41 seconds the receiver is able to decode the data, after which the new transmitting cycle begins with the next even numbered minute.

What’s the use of the WSPR-Beacon?

A worldwide network of WSPR receivers is linked via internet and receives the decoded WSPR packages, which are received from all over the world, into a general available data bank. From this the radio amateur can retrieve information regarding propagation on the various HF bands. The filter function is very interesting. Our beacon V53ARC can be filtered out here. One is able to determine precisely the actual propagation. The data bank is available at www.wsprnet.org. One can select from the Menu on the top right hand side, “Map” or for instance “Database”.