WSPR: Weak Signal Propagation Path Reporting

WSPR (pronounced “whisper”) stands for “Weak Signal Propagation Reporter”. It is a protocol, implemented in a computer program, used for weak-signal radio communication between amateur radio operators.

WSPR implements a protocol designed for probing potential propagation paths with low-power transmissions. Transmissions carry 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.


Applications for WSPR

The protocol was designed to test propagation paths on the LF, MF and HF bands. Also used experimentally at VHF and higher frequencies.

Other applications include antenna testing, frequency stability and frequency accuracy checking.

Usually a WSPR station contains a computer and a transceiver, but it is also possible to build very simple beacon transmitters with little effort.

For example simple WSPR beacons can be built using the Si 570 crystal oscillator (see PDF for kit links and schematics), or Si 5351 (kit available here).

The Raspberry Pi can also be used as WSPR beacon.

Photo Credit: Gerolf Ziegenhain – Own work, CC BY-SA 3.0

Article Link: Raspi as WSPR Transmitter
Source Code:

Here’s another example DIY WSPR beacon project video:

Source Files for Project on Github

Download WSPR Software at the Official WSPR Site: