The TRXW is based on the Weaver method (often also called third method) invented and patented by Donald K Weaver in 1956 (see here: https://patents.google.com/patent/US2928055).

For a good tutorial how this method works see this tutorial: https://forum.pjrc.com/attachment.php?attachmentid=9746&d=1487439697

The TRXW is based on a transceiver designed by B.Kainka in 1984, see http://www.b-kainka.de/SSBtrx.pdf for the german original version.