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by peter_d_sherman·1y ago·view on hn ↗

>"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)."

[...]

>"If you’ve wondered if a [ham radio, more broadly rf] band is open, WSPR can tell you."

WSPR sounds somewhat analogous to 'ping' or perhaps 'traceroute' -- but for HAM radio (or more broadly, radio, rf) signal propagation paths...

https://vkradioamateurs.org/introduction-to-wspr/

>"The program can decode [weak] signals with S/N as low as −34 dB in a 2500 Hz bandwidth."

https://www.sigidwiki.com/wiki/WSPR

https://en.wikipedia.org/wiki/WSPR_(amateur_radio_software)

>"Stations with internet access can automatically upload their reception reports to a central database called WSPRnet, which includes a mapping facility.":

https://www.wsprnet.org/drupal/wsprnet/map

The cool thing about WSPR is the weak signal aspect. I don't understand the math, but a receiver and the program to decode it can dig a signal out below the noise floor. If the band is open, you can literally transmit into a light bulb and have your signal picked up by dozens of receivers across the country. It's wild. And fun.