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What to listen to · Amateur radio
WSPR on 40 metres: 7038.6 kHz, evening propagation in two-minute slices
WSPR on 40 m shows the band waking up: neighbours at noon, the whole continent after sunset, other continents in the small hours. Milliwatt beacons on 7038.6 kHz draw the picture every two minutes.
What you hear
The two-minute whisper of WSPR, explained in the main article, in a 200 Hz window at 7040.0 to 7040.2 kHz. By day the lines are few and the decodes come from a few hundred kilometres; from late afternoon the window fills, and after midnight the locators in the decodes belong to other continents.
Who transmits and why
Propagation watchers and low-power experimenters who want to see the low bands at work. 40 m is the band most amateurs have an antenna for, so the density of transmitters is high, and the data gives the most complete picture there is of how a night band opens and closes. The segment sits just above the CW part of the band, next to the other narrow digital modes.
When and where to listen
Any time, but the interesting hours run from sunset to sunrise, when the reach grows from regional to intercontinental and back. Summer static makes the weakest lines harder to decode; winter nights are the cleanest. A rural receiver sees the most. The dial is 7038.6 kHz in USB, as always for WSPR, and the signals occupy only the narrow window 1400 to 1600 Hz above it.
In ShackDeck
Station catalogue → Amateur radio → WSPR 40 m. The program picks a public receiver with 7038.6 kHz, sets the WSPR mode with its narrow passband and runs the decoder; every two minutes the callsigns, locators and powers appear in the On air list and the stations on the map. No receiver, antenna or account of your own is needed.