What is WSPR?
I can best describe this by quoting verbatim from K1JT's WSPR webpage. K1JT is the person who created modes such as JT6m.
"WSPR implements a protocol designed for probing potential propagation paths with low-power transmissions. Each transmission carries a station's callsign, Maidenhead grid locator, and transmitter power in dBm. The program can decode signals with S/N as low as -28 dB in a 2500 Hz bandwidth. Stations with internet access can automatically upload their reception reports to a central database called WSPRnet, which includes a mapping facility."WSPR-2 is essentially an attended beaconing mode which sends a series of 6Hz wide FSK transmissions with data including callsign, QTH locator and TX power for about 2 minutes then listens in a 200Hz band for similar transmissions. When any signals are successfully received and decoded the logs can be automatically uploaded to a webpage where all users can see them. So, you can see who is picking up your signal and how far they are away. As the system can work with very weak signals because of its clever signal processing, QRP powers only are needed. Indeed this is an ideal mode for QRPp experiments down to mW or uW levels.
As of early January 2013 there is now a new version called WSPRX which also supports a slower, even more sensitive, version called WSPR-15 which will successfully decode signals buried even deeper in the noise.
The typical WSPR screen is shown above. The DOS like terminal window shows the port settings for audio in/out. The screen with the waterfall like display shows the received WSPR signals (1 minute long) and those successfully decoded, together with relevant data for each station logged. On the WSPR Spots database is more useful online data showing all received logs and these can be filtered by callsign, band, etc.
G4ILO's Distant Whispers page - an excellent introduction to WSPR
WSPRspots - where you can see almost realtime DX WSPR loggings
WSPRnet - the WSPRnet home page
K1JT's WSPR webpage - K1JT wrote the software for WSPR. JT65, JT6M etc. He's a Nobel Prize winning physicist when not writing clever ham software!
http://physics.princeton.edu/pulsar/K1JT/EME_Florence_2008.pdf - a paper on WSPR theory including how WSPR sensitivity compares with other modes like CW.
This evening (August 13th 2009), VK8CH (Australia) copied both my 10W, then 5W QRP 40m WSPR signals. DX was 13800kms - not bad for a small end-fed wire about 15m long strung down the garden only 6m at the highest end and 2.5m high at the far end! the next evening he copied my 2W signal.
WHERE IS THE SOFTWARE?
Download WSPR software for Windows free at K1JT's WSPR download site .
ABOUT JOE TAYLOR, K1JT
Joe Taylor wrote the software for WSPR. He is a very clever and, by all accounts, very decent person too, I see he is a Quaker. He is also a Nobel Prize winning physicist for his work on astronomy and relativity. Details about Joe and his distinguished career may be found at http://en.wikipedia.org/wiki/Joseph_Hooton_Taylor,_Jr.