Aldo is a morse code learning tool released under GPL, which provides four types of training methods: Classic exercise: Identify random characters played in morse code. Koch method: Two morse characters will be played at full speed (20wpm) until you are able to identify at least 90 percent of them. After that, one more character will be added, and so on. Read from file: Identify the morse code generated from a file. Callsign exercise: Identify random callsigns played in morse code.