WSPR (pronounced "whisper") stands for "Weak Signal Propagation Reporter".
WSPR implements a protocol designed for probing potential propagation paths with low-power transmissions. Transmissions carry a station's callsign, 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.
The WSPR protocol compresses the information in the message into 50 binary digits.
WSPR characteristics:
- data to send:
- callsign (28 bit)
- QTH locator (15 bit)
- power level in dBm (7 bit)
- speed 1.4648 baud
- forward error correction
- continues phase 4-FSK modulation
- tone separation 1.4648 Hz
- bandwidth 6 Hz
- transmission duration 110.6 seconds
- two-minute time slots for transmitting and receiving.
- transmissions nominally start one second into an even UTC minute:
i.e., at hh:00:01, hh:02:01, ...
- transmissions nominally start one second into an even UTC minute:
Stations with internet access can automatically upload their reception reports to a central database called WSPRnet.org, which includes a mapping and filtering facility.
WSPR World Watch (Android app)
This app plots radio transmission paths observed in real-time on a world map which can be centered either on the Atlantic or the Pacific.
It also plots the greyline and displays current Space Weather indexes and may optionally plot Aurora ovals.
