WSPRnet Weak Signal Propagation Reporter Network
Wikipedia says: WSPR (pronounced “whisper”) stands for “Weak Signal Propagation Reporter”. It is a computer program used for weak-signal radio communication between amateur radio operators. The program was initially written by Joe Taylor, K1JT, but is now open source and is developed by a small team. The program is designed for sending and receiving low-power transmissions to test propagation paths on the MF and HF bands.
I set my station to ‘listen’ on 30m to see what kind of conditions etc. Here’s the screen shots from various 24 hour periods recently