Vold-Kalman order tracking code

Separates system orders from single channel of rotating machinery data.

Vold-Kalman second generation, multi-order, simultaneous order tracking code (vkm.m).
This method is valid for extracting multiple crossing orders.

Written by Scot McNeill because I got tired of not having access to the V-K method for my
research and decided to program it myself.

Prof. Jiri Tuma has posted m-code for the single-order routine (MyVoldKalman2.m) in publications on
his website [1]. Note that MyVoldKalman2.m was also published in a Matlab conference paper.
However, the M-code for the simultaneous, multi-order implementation [2] was not posted.

Note that Prof. Tuma posted p-files for all his V-K routines, including simultaneous, multi-order
tracking routine. The P-files didn't work on my vintage of Matlab (2007a), so
I just decided to implement [2] myself. I provide this first-draft implementation (vkm.m) for other
researchers. M-code is provided.

The additional routine, vk2.m, which does second generation, single-order, noncrossing order tracking
is based on MyVoldKalman2.m [1]. vk2.m is provided as a comparison to vkm.m.

Thanks to Prof. Tuma for making his concise matlab routine (MyVoldKalman2.m) available in his
publications.

This implementation has not been rigorously tested and is made available as-is. It is the user's
responsibility to verify output of the routine.

To get started, run the m-files in the demos folder.

References:

[1] J. Tuma, Vold-Kalman order tracking filtration, PDF presentation slides online at
http://homel.vsb.cz/~tum52/index.php?page=download

[2] C. Feldbauer and R. Holdrich, Realization of a Vold-Kalman filter - A least squares
approach, Proceedings of the COST G-6 conference on digital audia effects (DAFX-00),
Verona, Italy, December 7-9, 2000. Available online at
http://iem.at/projekte/publications/paper/dafx_feldbauer_hoeldrich2/dafx_feldbauer_hoeldrich2.pdf