Step 1: Spectrum Lab software
The type of display used here is called the "waterfall" display, and it is set to scroll from right to left. It traditionally scrolls from top to bottom, and hence the term, waterfall.
This program is used by amateurs to communicate halfway around the earth with fractions of a watt, among other things. It is a very capable program, and has a multitude of settings which have to be adjusted just right to result in a good display.
The term "Hellschreiber" originated in the field of telegraphy, a long time ago, and literally means writing with light.
The display shown on the introduction is a plot of intensity of frequency against time.
The microcontroller is programmed to generate a series of tones, such that an image of the information is painted by this program.
This mode is defined as "sequential multi tone Hellschreiber" and is used for communicating over long distances using relatively simple transmitting equipment.