IIO Oscilloscope 
The IIO Oscilloscope is a GTK+ application, which demonstrates how to interface various IIO devices to different visualization methods within a Linux system.
The application supports plotting of the captured data in three different modes:
- time domain
- frequency domain and
- constellation (X vs Y)
The IIO 'scope supports a plugin architecture which many people use to view and modify settings of the attached IIO device(s).
The main documentation for the IIO 'scope (including checkout/build instructions) can be found at: https://wiki.analog.com/resources/tools-software/linux-software/iio_oscilloscope#installation
Source can be found at: https://github.com/analogdevicesinc/iio-oscilloscope
Bugs can be reported at: https://github.com/analogdevicesinc/iio-oscilloscope/issues
The IIO 'scope uses:
- FFTW, a C subroutine library for computing the discrete Fourier transform (DFT) in one or more dimensions, of arbitrary input size, and of both real and complex data http://www.fftw.org/
- inih, a simple .INI file parser written in C http://code.google.com/p/inih/
The IIO 'scope is copyright its authors, and is released under the GPL 2.0