It looks like this may be a list of FBI ALE ("Automatic Link Establishment") radio stations. See page 17 of https://worldradiohistory.com/Archive-Monitoring-TIm

It looks like this may be a list of FBI ALE ("Automatic Link Establishment") radio stations. See page 17 of https://worldradiohistory.com/Archive-Monitoring-TImes/2000s/Monitoring-Times-2000-06.pdf https://worldradiohistory.com/Archive-Monitoring-TImes/2000s... and https://www.sigidwiki.com/wiki/Automatic_Link_Establishment_(2G_ALE) https://www.sigidwiki.com/wiki/Automatic_Link_Establishment_... From wikipedia (https://en.wikipedia.org/wiki/Automatic_link_establishment https://en.wikipedia.org/wiki/Automatic_link_establishment): "[ALE is] the worldwide de facto standard for digitally initiating and sustaining HF radio communications.[1] ALE is a feature in an HF communications radio transceiver system that enables the radio station to make contact, or initiate a circuit, between itself and another HF radio station or network of stations. The purpose is to provide a reliable rapid method of calling and connecting during constantly changing HF ionospheric propagation, reception interference, and shared spectrum use of busy or congested HF channels."