Interesting Hellschreiber Videos

Hellschreiber, or Hell, is a method of sending and receiving text using facsimile technology. It is unique in that the characters are not decoded, but "painted" or printed on a screen. There are several modes of Hellschreiber, the most popular being a single-tone version call Feld-Hell, an on-off keyed system with 122.5 dots/second, or about a 35 WPM text rate. FH has a narrow bandwidth of about 75 Hz. Feld-Hell also has the advantage of having a low duty cycle meaning your transmitter will run much cooler with this mode.