FIGURE 8. WSPR operating window.
coax cable may help.
Now, set your computer clock to
UTC within one second or so.
Correct UTC can be found on the
Web. We use the Naval observatory
www.usno.navy.mil. Now comes
the anxious part. You need to wait
for an even numbered minute (0, 2,
4, etc.) for the software to begin
receiving. Watch your computer
clock. At this point, the message in
the lower right corner will change
from “waiting” to “receiving.” The
lower left corner will specify the level
of the input audio in dB. This can be
adjusted with your sound card
recording level control.
A level of 12 to 19 dB works
well, even though the software says
otherwise and produces a red
window. There are a few other things
you can do, like putting in your grid
location and call (or name) if you
want to report your spots. But that
will come later. For now, sit back and
watch for your first catch.
WSPR is amazing technology.
The simplicity of the WSPR receiver
described here makes it attractive as
a low cost radio propagation tool.
With a bit of luck, it will motivate
experimenters, teachers, and students
to begin exploring the many facets of
science and engineering touched
As stated, the question, “How
does that work?” is indeed the key to
curiosity. Hopefully, it will help the
young stay interested in science.
This receiver is only the first step.
Other projects involving more
sophisticated receivers and
transmitters will surely follow. There
was recently an article “Chips In
Space” by Mason Peck (IEEE
Spectrum August ‘ 11) which
described how satellites the size of
small integrated circuits could
revolutionize the way we explore
space. Project Sprite involves
designing and later on launching
many thousands of low mass chips
(under 50 milligrams) for the single
purpose of monitoring space with
simple sensors. Each chip will have a
weak radio transmitter and signal
barely discernable from noise.
Sophisticated signal processing
software will be needed to pull the
signals out of the noise.
Perhaps a youngster intrigued by
WSPR will be the future engineer to
design that software. NV
January 2012 49