[amsat-bb] XW-2D linear transponder signal id

Hi - can anyone identify this signal often heard on the XW-2 birds?

http://swigerco.com/gqrx_20190311_223926_145869769.wav

I enjoy listening to the SSB qso's on them, but curious what that is, sounds almost like a very slow fax like https://www.sigidwiki.com/wiki/WEFAX

One was particularly strong this morning https://network.satnogs.org/observations/555759/ (the line around +15KHz on the waterfall) along with another weaker one.

Just curious.

Thanks de kb4new