link dump - ALSA etc - for software lock-in amplifier

ALSA tutorial for beginners - 2004 - http://www.linuxjournal.com/article/6735?page=0,1

PortAudio - http://www.portaudio.com/

ALSA example
https://gist.github.com/albanpeignier/104902

Another ALSA tutorial - http://equalarea.com/paul/alsa-audio.html

Checking the code and compiling from https://www.av8n.com/physics/lockin.htm

http://www.qtcentre.org/threads/53452-QtGui-QApplication-No-such-file-or-directorty

QApplication and Qwidgets derived classes are in widgets module in Qt 5 so to fix that you need to add QT += widgets in the .pro file and run qmake and also use #include <QApplication> instead of #include <QtGui/QApplication> (and the code becomes compatible with both Qt 4 and 5), you can read more here

Or download 10.04,

and
https://help.ubuntu.com/community/Installation/FromUSBStick#Install_and_run_Startup_Disk_Creator_alias_usb-creator