As noted by Joe Taylor, K1JT, and Bruce Walker, W1BW, in their November 2010 QST article, “WSPRing Around the World,” WSPR transmits and receives

Ham Radio 101: What is WSPR?

submited by

Style Pass

2024-11-08 01:00:06

As noted by Joe Taylor, K1JT, and Bruce Walker, W1BW, in their November 2010 QST article, “WSPRing Around the World,” WSPR transmits and receives but does not support normal types of on-the-air conversation. It sends and receives specially coded, beacon-like transmissions which establish 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).

K1JT notes that FEC greatly improves chances of copy and reduces errors to an extremely low rate. The signal bandwidth is only 6 Hz. Combined with randomized time-sharing, this assures that dozens of WSPR signals can fit into a 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, about 10 to 15 dB below the threshold of audibility. On most bands, typical WSPR power levels are 5W or less (sometimes significantly less).

As the protocol has evolved, enhancements to WSPR have included upgrades in its decoder’s sensitivity, improved ability to handle larger numbers of signals in crowded sub-bands, and better detection of false decodes.