I am learning signal processing. For a hobby project I wanted to transmit and record a simple ASK signal via my soundcard, to see if I can write code to recover the sent data. After playback and recording, the recorded signal isn't even close to the original. I thought that the problem was my code, but I could not fix it.
Eventually I tried to play back and record a square wave signal with Audacity. The results of the recording can be seen in the picture. The recorded signal does not look like a square wave. But it sounds the same and the spectra look similar.
Can anyone help me with this problem? How it is possible to record a "real" square wave signal?