You're relatively new here, so here's a tip; the blue text a417 sent in his message represents a link. I would highly encourage you to read that first one, as it's pretty up to date. Blue text links are also common in our wiki, which is the largest radio related wiki on the planet, bar none.
Now to your question - 7527 khz (notice that it's common to refer to frequencies below 30 Mhz in this manner) is often noted in the Utility DXers Forum reflector on groups.io as using 'ALE' - specifically ALE/USB. ALE means Automatic Link Establishment, and goes by several other names. The USB indicates that the tones are sent on Upper Sideband. It is certainly possible - and several other organizations do this - to send those tones on the Lower Sideband. This is a digital mode that is, for the most part, easily decoded and copied
Some more information on this mode (many times it is referred to as '2G ALE') can be found here, along with links to apps that can copy it
Automatic Link Establishment, 2G ALE (Official designation MIL-STD-188-141A and/or MIL-STD-188-141B (Appendix A)) is the current standardized method of establishing connections between radio operators. Also known as FED-STD 1045, FED-STD 1049, and STANAG 5066.
www.sigidwiki.com
Mike
groups.io
