The Radio Whisperer
A unique circuit, a few feet of wire, and some powerful software combine to make an
amazing communications tool capable of spanning the world.
By George Steber
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Advances in communications in recent years have come at a startling pace. In the old days, to
communicate via radio one needed a good antenna, a selective receiver, and a powerful transmitter.
While those items are still useful, today there is one more item required: good software. The “weak
signal propagation reporter” software or WSPR (pronounced “whisper”) is one such advanced
methodology. WSPR will astound you with its ability to communicate globally using very low power
with received signals at or near the noise threshold. We are talking (in this context) about
transmitting power levels of 500 milliwatts (mW) and often much less. One of my WSPR signals was
received 1,600 Km away from my home while I was using only 10 mW of transmitter power and a
short 24 foot length of wire. Low power WSPR signals were received on the same piece of wire from
over 6,000 Km away.
If you are interested in learning more about this technology and how you can participate by building your own low cost WSPR receiver, keep reading. We will cover all of that and more. Before we get to that,
let’s talk about a special application. If you are an
educator or know someone involved in teaching science,
please take note. WSPR is not only for electronics
experimenters, but can be used to help teachers motivate
their students in science while presenting relevant
technical methodology. Motivation will likely occur
because WSPR encompasses a wide range of subjects
such as electronics, communications, Internet, software,
physics, geography, and more.
FIGURE 1. World map from