HFU HF Underground

Loggings => Shortwave Broadcast => Topic started by: Dan_Streetmentioner on March 11, 2026, 0354 UTC

Title: Broadcast on 13.570 MHz.
Post by: Dan_Streetmentioner on March 11, 2026, 0354 UTC

Greetings Readers,
I am doing an HF propagation study by monitoring the carriers of various AM stations. Attached is an image of a signal strength plot. Can any body please explain the behaviour of the signal shown. On the hour the signal turns on for 7m 30s then off for 7m 30sec(15 minutes) and continues this on/off switching for the next 10 hours.

Dan Streetmentioner.