Order analysis or order tracking
Well my friend, if you read the following B&amp;K tutorial about the Order Tracking, then you should encounter so called Vold-Kalman Order Filtering. Personally I don't like it (rather prefer Chirp-Fourier based methods for extracting the response of the system).

You can find plenty implementations in the internet. When you look for MATLAB, then please refer to:

Vold-Kalman order tracking code

Second generation Vold-Kalman Order Filtering.

And most certainly I suggest you to search the bottom of the prof. Jiri Tuma website: click!

For more theory please take a look at - I'm sure you will like it:

Characteristics of the Vold-Kalman Order Tracking Filter

Vold-Kalman Order Tracking Filtration

Main Principles and Limitations of the Current Order Tracking Methods

Realization of the Vold-Kalman Tracking Filter - A Least Squares problem

Advanced Vold-Kalman Filtering Order Tracking - do not be scared, it's not in chineese ;)