The android screen above shows a ghost (mirrored) image. This is the result of aliasing.
When I saw the explanation involved a discussion of negative frequencies, I quickly
skipped ahead and installed an additional low pass filter.
A program to display the dc.wav file:
www.qsl.net/zs1agx/shell/shell.html#dl
This is for win32 with .net 2.0 , so a really old winxp or win7 should be ok.
unzip the file into maybe d:\programs
The program displays a slowly scrolling waterfall from either .wav or line input
across 750...2300Hz. The display is averaged to reduce noise, so the character pixels
of dc.wav soften a little. Keep to low input level. This program takes less than 3% cpu
time and less than 15M RAM (even less when reading a .wav file rather than line input).
Additional extra program setting items have been included (especially for you in
particular) so as to allow you to experience the highest level of click satisfication
possible with such a program.
alias.jpg scribble01.jpg