I’ve been monitoring the U.S. military's High Frequency Global Communications System (HFGCS)—the shortwave radio network best known for broadcasting Emergency Action Messages—since January 2022. This includes extended periods of continuous 24/7 coverage, among them an unbroken stretch from June 2023 to February 2024. Recordings and transcriptions published across YouTube and social media represent one of the few sustained public efforts to document and characterize activity on this network.
