QRQ CW 'copy by ear' PRACTICE using Mixxx with CW REGENERATION & a tracking CW audio bandpass filter

[Chuck aa0hw]

Mixxx is a VARIABLE SPEED audio player that works great to slow down or speed up a QRQ CW audio file. Mixxx also has a REVIEW/rewind function that allows you to repeat the last word sent as many times as you want(by hitting the keyboard letter 'A' ...you can also repeat while slowing it down... MIXXX will change the cw frequency however.... and to keep the pitch the same, no matter the speed that MIXXX is running at.... a CW REGENERATION method is employed. the CW REGEN uses a sidechain GATE app called ZAMGATE in sidechain mode. at the upper port of zamgate is a pure sine wave tone generator.... but only passes through ZAMGATE to its output when the sidechain port is 'keyed' by the CW AUDIO output of MIXXX... to be able to smooth out the edge noise a CW BANDPASS FILTER is added to the ZAMGATE OUTPUT... and to be able to produce a TRACKING CW AUDIO BANDPASS FILTER, no matter the CW PITCH CHOSEN an SDR MODULE is used... LO-MIXER by adjust LO-MIXER the center of the BANDPASS FILTER is kept at its center point as well as all the characteristics of the bandpass filter width and filter length...all can be adjusted to suit your desired cw tone

ZAMGATE https://www.zamaudio.com/ SINE WAVE OSC, BP FILTER, LO-MIXER from

RECRI KEYER: https://github.com/recri/keyer

MIXXX https://mixxx.org/

EBOOK2CW app to create the cw mp3 files from text to cw audio: https://fkurz.net/ham/ebook2cw.html