How does he do that? The answer…
June 28th, 2009
…is, that he is using a form of Hellschreiber, a fax like data transmission mode. Hellschreiber (also known as Feldhellschreiber, Feld-Hell or simply Hell ) was invented br Dr Rudolf Hell in the late 1920’s and early 1930’s and was developed to provide intelligible communication even over very poor quality radio or cable links.
You can read more about Hellschreiber in the wikipedia article here.