The "noise" is a digital mode called DIGTRX. It's sending files in encrypted text.
Small nit here.
The mode is called RDFT (Redundant Digital File Transfer), the most common software used by hobbyist to demodulate that mode is DIGTRX. The RDFT mode was developed as a ham radio mode around 2001, and started being used by HM01 in about 2012. Prior to HM01, the Cubans used the same RDFT (and a couple other modes, also) with HM01's predecessor signal, SK01, starting in about 2007.
There have been a couple of different beta and experimental softwares that could work with RDFT, but DIGTRX is by far the most common, and the only one that I know of that has a chance of running on a reasonably recent OS.
T!