WSPR
From Wikiham, the ham radio free encyclopedia
WSPR, pronounced “whisper”, stands for Weak Signal Propagation Reporter. It is a digital beacon protocol associated with Joe Taylor, K1JT, and the WSJT project. Stations transmit brief identification and location information so reception reports can reveal radio propagation paths.
Standard message
A conventional Type 1 message contains a callsign, a four-character Maidenhead locator and a transmitter power level in dBm. These fields are packed into 50 information bits. Other message formats support cases that do not fit this basic layout.
For example, a power field of 30 dBm means 1 W. The stated transmitter power is not a measurement of antenna gain or radiated power in a particular direction.
WSPR-2 waveform
The widely used two-minute form uses four-frequency shift keying, error correction and a known synchronisation pattern. It sends 162 symbols with tone spacing and symbol rate of approximately 1.4648 Hz and 1.4648 baud respectively.
Symbol duration = 8192 / 12000 ≈ 0.6827 s Transmission time = 162 × 8192 / 12000 ≈ 110.6 s
The occupied bandwidth is about 6 Hz. Transmissions are arranged in two-minute UTC slots; accurate timing and frequency stability help receivers find and decode them. WSPR is a beacon/reporting system, not a normal two-way conversational QSO mode.
Interpreting reports
Reports may contain received SNR, frequency and drift. Reception depends on the transmitting and receiving antennas, noise, propagation and whether a receiver was listening at that time. A missing report alone does not prove that a band was closed or that an antenna failed.
A fair antenna comparison keeps power, schedule and receiving conditions as consistent as possible and uses many observations. Uploaded reports can be viewed through WSPRnet and related tools; receiving a signal does not require every transmitter to have an Internet connection.