SETUP: an UltraPico Keyer, keys a 555 TIMER CHIP..from the audio output of the 555, an audio cable is attached and goes to the input of a laptop's mic jack input...the 555 time chip sidetone is very rough sounding with lots of high pitched harmonics and key clicks...INSTEAD of trying to filter the 555's raspy tone, this video demo's using TRIGGER MIDI MONO to recreate the original 555 sidetone cw element and then a LINUX LV2 PLUGIN called TRIGGER MIDI MONO keys another CPO, a software code practice oscillator synthesizer called SIMPLE SINE GENERATOR(lv2 plugin)...this SIMPLE SINE GENERATOR has zero rise or fall time and therefore has loud key clicks...so those need to be filtered out....by another LINUX LV2 PLUGIN called CALF FILTER...calf filter does a great job of taking out all the harmonics and key clicks and produces a nicely shaped cw element audio waveform output
Previously, this CW REGENERATION technique was accomplished using WINDOWS VST PLUGINS, or a non free app called LINUX NATIVE REAPER. After discovering this TRIGGER MIDI MONO plugin for LINUX, this CW REGENERATION technique can now be utilized with ALL FREE LINUX APPS ...
NOTE: familiarity with KXstudio, and his LINUX JACK AUDIO APPS for Linux is necessary in order to understand fully, the method that is being demo'd...there are more videos in this QRQcw youtube channel to learn more about JACK AUDIO for LINUX/windows/mac and the Raspberry Pi....
NOTE: MIDI DATA MESSAGES, of NOTE ON and NOTE OFF are used to instruct (key) the software code practice sine wave oscillator APP called SIMPLE SINE GENERATOR. (there are other LINUX audio plugins that would also work like AMsynth) -https://github.com/amsynth/amsynth
MIDI DATA MESSAGES - WHAT IS MIDI ?