Picked up one of these ...
Setup was a breeze less then 5 minutes I was on 80m and this is the initial result....
and a little about the modulation ...
software utilizes an extremely narrow frequency band with
specially-coded forward error correcting (FEC) and
frequency shift keying (FSK). FSK is like very narrow band
FM. This technique reduces errors and improves the
possibility of copying the message in noise. The signal fits
into a tiny 200 Hz segment. Within each segment, the
signal bandwidth is only 6 Hz. This allows several tens of
stations to coexist in a segment with minimal interference.
There are 12 segments presently (denoted here as the
WSPR bands), located within the radio frequency
spectrum (see Figure 2).
The WSPR protocol is extremely effective at signal-tonoise
ratios as low as –28 dB in a 2,500 Hz bandwidth.
This is over 10 dB below the threshold of audibility. In
other words, you can sometimes copy signals that you
cannot hear. It is because of this capability that even low
power WSPR signals can be decoded in the farthest
reaches of the globe. WSPR is designed to do just
one thing: find a communication
path. It communicates via specially
formatted messages aimed at
determining if a propagation path is
open on a given transmitting
frequency. Formatting contains a
name, four character grid locator,
and power level in dBm (decibels
relative to one milliwatt). This
information is compressed into 50
binary digits and encoded using a
convolutional code of length 32 and rate 1/2. The
resulting 162 bits are transmitted using four tone FSK at
1.46 baud. The least significant bit is defined by a pseudorandom
sequence known by the software at both
transmitter and receiver. It is used to establish accurate
time and frequency synchronization. Long convolutional
codes are advantageous since undetected decoding errors
are rare. Normally, a Viterbi algorithm is used for decoding
but due to complexity, the WSPR decoder uses a special
When a station is decoded, other information such as
“receive location,” name, S/N ratio, and DT (time
difference) is routinely logged. This information can be
automatically downloaded to WSPRnet.org using the
“spots” option. Your name will then be shown on a
flag on a world map with others. Options on the
website can be used to find the distance and direction
of the station received.