http://dspillustrations.com/pages/index.html
http://jackschaedler.github.io/circles-sines-signals/
Fourier transform
https://news.ycombinator.com/item?id=16242103
https://news.ycombinator.com/item?id=9762022 Fourier transform
http://cns-alumni.bu.edu/~slehar/fourier/fourier.html
DSP Book
http://www.ece.rutgers.edu/~orfanidi/intro2sp/
http://www.dspguide.com/pdfbook.htm
http://sam-koblenski.blogspot.com/2015/10/everyday-dsp-for-programmers-signal.html
Kalman
https://habrahabr.ru/post/328146/ Kalman
https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
https://www.johndcook.com/blog/2016/07/14/kalman-filters-and-functional-programming/
http://www.bzarg.com/p/how-a-kalman-filter-works-in-pictures/
https://news.ycombinator.com/item?id=13449229
https://www.cl.cam.ac.uk/~rmf25/papers/Understanding%20the%20Basis%20of%20the%20Kalman%20Filter.pdf
http://dspguru.com/dsp/faqs/multirate/decimation
http://www.anuncommonlab.com/articles/how-kalman-filters-work/
https://news.ycombinator.com/item?id=11561770
http://www.bzarg.com/p/how-a-kalman-filter-works-in-pictures/
https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
http://alexander-mikh.livejournal.com/253672.html
http://greg.czerniak.info/guides/kalman1/
http://bilgin.esme.org/BitsBytes/KalmanFilterforDummies.aspx
http://www.cs.unc.edu/~welch/kalman/
http://www.codeproject.com/Articles/469458/Kalman-Filtering-Part
http://habrahabr.ru/post/166693/
http://www.rusdoc.ru/articles/filtr_kalmana__vvedenie/20004/