30 Sep WSPR – Weak Signal propagation Reporter
Last Updated on February 17, 2023
WSPR stands for “Weak Signal Propagation Reporter”… a protocol used for weak-signal radio communication between amateur radio stations. It’s fully automated and reports to the WSPRnet.org server in real-time. In the video below, we’ll take a quick look at WSPR and what you can learn from it.
If you’ve wondered if a band is open, WSPR can tell you.
If you’ve wondered if you should get up early to work some DX, WSP can tell you.
From HF to UHF, WSPR has you covered, all you need is an internet-connected device to see if your favourite band is open.
WSPR is a beacon system to study radio propagation and first appeared in November 2010. It was developed by Emeritus Professor Joe Taylor, an American astrophysicist based at Princeton University. Joe first obtained his amateur radio license as a teenager in 1954, which led him to the field of radio astronomy. His callsign is K1JT. His Amateur Radio feats have included mounting an ‘expedition’ in April 2010 to use the Arecibo Radio Telescope to conduct moonbounce with Amateurs around the world using voice, Morse code, and digital communications.
WSPR was originally called MEPT which stood for Maned Experimental Propagation Tests.
The protocol is designed for sending and receiving low-power transmissions to test band propagation and can be found in the WSJT-x software which can be downloaded from the Princeton University site.
This mathematically sophisticated method of encoding information ensures that with very high probability, messages displayed by the decoding software will be exactly those that were originally encoded.
WSPR transmits and receives, but it does not support normal types of on-the-air conversation. Instead, it sends and receives specially coded, beacon-like transmissions aimed at establishing whether particular propagation paths are open. Transmissions convey a callsign, station location, and power level using a compressed data format with strong forward error correction (FEC) and narrow-band, four-tone frequency-shift-keying (FSK).
The Forward Error Correction greatly improves chances of copy and reduces errors to an extremely low rate. The signal bandwidth is only 6 Hz, which together with randomized time-sharing assures that dozens of WSPR signals can fit into a tiny 200-Hz segment of each amateur band.
The WSPR protocol is effective at signal-to-noise ratios as low as –28 dB in a 2500 Hz bandwidth, some 10 to 15 dB below the threshold of audibility. On most bands, typical WSPR power levels are 5 W or less – sometimes a lot less.
All transmissions start on the even minute and last 2 minutes and your computer clock accuracy must be within 1 sec.
The WSPR protocol continues to evolve. Recently significant improvements were made to the WSPR decoder’s sensitivity. Its ability to cope with many signals in a crowded sub-band and its rate of undetected false decodes has been enhanced.
WSPR can be used on pretty much any amateur band. To run WSPR, you’ll need a radio, preferably one which has USB audio, a computer, and an internet connection. It’s worth noting that you don’t need to transmit. Your system can still report what it hears.
WSPR talks to other computers, not humans. Stations always listen and occasionally transmit. It uses a 2kHz window and reports what it hears – or spots, back to WSPRnet.org. Even if you don’t have a WSPR station you can check the map ay WSPRnet.org at any time to see the conditions of the bands.
There are plenty of videos online to show you how to use WSPR, but it’s worth considering adding WSPRnet.org as a bookmark in your browser.
If you have an iPad or iPhone, download a free copy of WSPR watch. It adds the world of WSPR to your device in a very graphical, and easy to consume way. It even generates TX audio for you if that would be your want. It’ll let you interact with spots and display the signal originating station information, even a link to QRZ.com and spot history within the app. There’s also a graphical representation of spots. The app scores a 4.9 out of 5 on the app store.
Conceived with just-for-fun, hobbyist motivations, WSPR has helped to bring some recent technical advances from the professional and scientific world into amateur radio, providing educational benefits as well as many hours of enjoyment for technically minded experimenters.
If you’re interested in propagation, then WSPR is for you. It’ll give you an insight into band activity before you even get into the shack. You will be amazed to discover where your QRP signals are copied, in distant corners of the world.