Spectra

A C library for spectral estimation and signal processing.

The main goal of Spectra is to provide a C library that can be easily used in scientific programming to perform spectral estimation and other operations such as spectrum sensing.

The spectral estimation functions try to imitate the behavior of SciPy, hence the source code structure of this part is very similar to that of SciPy.

I started developing this library while working on a project funded by the European Space Agency (ESA) at Dapcom Data Services (ESA Contract No. 4000137290) .

Project information

Features

Spectral estimation methods:

• Periodogram.
• Averaged periodogram (Welch's method).

Supported window types:

• Rectangular.
• Hann.
• Hamming.
• Blackman.

Other features:

• Noise power estimation.
• Energy detector.

If you are missing some features first make sure that they are not listed below. Otherwise check how can you contribute.

Work in progress

Here there is a list of some features that I know that are missing:

• Support for real FFT (input data type must be checked).
• Padding support to avoid discarding the last frame if it it smaller.
• Support for Cross Spectral Density (CSD) estimation.
• Support for median averaging in the Welch's method.

Documentation

The project documentation is managed with Doxygen. It can be generated by running doxygen on the root of the repository. This will create the directory docs/ with all the documentation in HTML.

Contributing

If you find a bug or you would like to suggest a new feature, feel free to open an issue.

Pull requests are also welcome but please create an issue first if it's a new feature.

Acknowledgements

I would like to thank the European Space Agency (ESA) and Dapcom Data Services for the funding that allowed the development of this library. I would also like to thank Jordi Portell for his contributions in the code.

License

This project is licensed under the BSD 3-clause license.
The KissFFT library is also licensed under the BSD 3-clause license.
The GSL library (only used in the energy detector) is licensed under the GPL-3.

Build

The compilation of this project is managed by CMake. You can either build the library or the different examples provided.

First we generate the build system:

cmake -B build .

To build all the targets we can execute:

cmake --build build

To build only one target:

cmake --build build --target <target_name>

The available target names are:

• spectra: builds the shared library.
• examples: builds all the examples (and also the library).
• detect_signal_aic_ed: builds only the example (and the library).

Troubleshooting

KISS FFT library not found

CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
KISSFFT_LIB
    linked by target "spectra"

1. Make sure that the library is installed or available in the lib project directory.
2. CMake searches for kissfft-float and kiss_fft_float in the lib directory of the project and also in the system library path. On UNIX, make sure that the files libkissfft-float.so or libkiss_fft_float.so exist. They must not have the version number at the end. If they do, you can create a symlink.