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Lecture "Adaptive Filters"


Basic Information

Lecture overview  
  Lecturers:   Gerhard Schmidt (lecture) and Tobias Hübschen (exercise)  
  Room:   Zoom  
  Language:   English  
  Target group:   Students in electrical engineering and computer engineering  
  Prerequisites:   Basics in system theory  

Students attending this lecture should learn the basics of adaptive filters. To achieve this, necessary algorithms will be derived and applied to problems arising in speech and audio processing. The algorithms comprise Wiener filtering, linear prediction, and adaptive schemes such as the NLMS algorithm, affine projection, and the RLS algorithm. For applications from speech and audio processing we use noise and reverberation reduction, echo cancellation, and beamforming.

Topic overview:

  • Introduction and application examples
  • Signal properties and cost functions
  • Wiener filter and principle of orthogonality
  • Linear prediction
  • RLS algorithm
  • LMS algorithm and its normalized version
  • Affine projection algorithm
  • Control of adaptive filters
  • Efficient processing structures
  • Applications of linear prediction



Summer term 2021: The lecture will be conducted using Zoom. The exercise will consist of both on-demand videos and of two Zoom meetings where student questions can be discussed. To receive all relevant information during the semester, including links to the Zoom meetings, please register for this lecture in Olat.

04.04.2021 - For the zoom link please have a look at the corresponding OLAT page. We will start the lecture on 20.04.2021 at 08:15 h.

23.03.2021 - Preliminary lecture and exercise schedule is available.



The following schedule regarding lectures and excercises is preliminary and may be adapted during the semester.

Date   Lecture   Exercise  
  20.04.2021   Introduction   -  
  27.04.2021   Wiener filter   Wiener filter (video)  
  04.05.2021   Linear prediction   Linear prediction (video)  
  11.05.2021   Algorithms part 1   -  
  18.05.2021   Algorithms part 2   Algorithms (video)  
  25.05.2021   -   Wiener, LP, Algorithms question time (zoom, will also occupy some of the lecture time)  
  01.06.2021   Control   Control (video)  
  08.06.2021   Processing structures   Processing structures (video)  
  15.06.2021   Applications of linear prediction   -  
  22.06.2021   -   Control, Structures, Applications question time (zoom, will also occupy some of the lecture time)  
  29.06.2021   Student talks   Student talks  
  06.07.2021   Student talks   Student talks  


Lecture Slides

Link   Content  
    Slides of the lecture "Introduction"
(Introduction, boundary conditions of the lecture, applications)
    Slides of the lecture "Wiener Filter"
(basics, principle of orthogonality, suppression of background noise)
    Slides of the lecture "Linear Prediction"
(derivation of linear prediction, Levinson-Durbin recursion)
    Slides of the lecture "Algorithms (Part 1 of 2)"
(RLS algorithm, LMS algorithm [part 1 of 2])
    Slides of the lecture "Algorithms (Part 2 of 2)"
(LMS algorithm [part 2 of 2], affine projection algorithm)
    Slides of the lecture "Control"
(basic aspect, pseudo-optimal control parameters)
    Slides of the lecture "Processing Structures"
(polyphase filterbanks, prototype lowpass filter design)
    Slides of the lecture "Applications of Linear Prediction"
(Improving the speed of convergence, filter design)



Link   Content  
    Extension for the lecture "Wiener Filter"
(derivation of the error surface)


Matlab Demos

Link   Content  
    Matlab demo (GUI based) for adaptive system identification  
    Matlab demo (GUI based) for adaptive noise suppression  
    Matlab demo (GUI based) for linear prediction  
    Matlab demo (GUI based) for the NLMS algorithms  
    Matlab demo (GUI based) for prediction-based filter design  



The exercise will consist of two parts using different media. For most lecture topics an individual exercise video will be uploaded. These videos can be watched on demand. Some additional course material will be provided alongside these videos.

The on-demand videos will be supported with two live zoom sessions. Here, students will be able to ask topic-related questions. Students are also encouraged to submit their questions ahead of time so the answers can be supported with slides or other material.

Videos will go live and zoom sessions will be conducted according to the (preliminary) schedule above.

Video   Content   Material  

Wiener filter:

  • summary
  • comprehension questions
  • python demo


Linear prediction:

  • summary
  • comprehension questions
  • signal visualization
  • python demo



  • summary
  • explaining algorithms
  • comprehension questions
  • python demo



  • motivation/summary
  • comprehension questions
  • python demo


Processing structures:

  • summary
  • comprehension questions
  • python demo



Student Talks

At the end of the semester, each student will give a talk about a certain topic as a prerequisite to sit the exam. The aim is both to give you the chance to work on an adaptive filter-related topic that interests you, and to improve your presentational skills. The talks should take ten minutes, plus 2.5 minutes of discussion and 2.5 minutes of feedback.

Please contact This email address is being protected from spambots. You need JavaScript enabled to view it. with your topic suggestion. Below you can find the current schedule of the talks.

Date   Room   Time   Topic   Presenter(s)  
  29.06.2021   Zoom   08:20 h   ECG Signal Enhancement Using Adaptive Filters   Moritz Boueke  
  29.06.2021   Zoom   08:35 h   Active Noise Cancellation for Headphones   Karolin Krüger, Christian Kanarski  
  29.06.2021   Zoom   09:00 h   Feedback Suppression   Finn Röhrdanz  
  29.06.2021   Zoom   09:15 h   Adaptive Filters in Power Electronics   Dario Metschies  
  29.06.2021   Zoom   09:30 h   Adaptive Beamforming in Radar Systems   Klara Görnig  
  29.06.2021   Zoom   09:45 h   Break      
  29.06.2021   Zoom   09:55 h   Adaptive Filters in Medical Image Processing   Mohammadmahdi Asrar, Karoline Gussow  
  29.06.2021   Zoom   10:20 h   Noise Suppression   Şevval Buse Tokmak  
  29.06.2021   Zoom   10:35 h   Adaptive Multi-Rate Codecs   Patricia Fuchs  
  29.06.2021   Zoom   10:50 h   Adaptive Filters in Fast HRTF Measurement   Simon Hesselbrock  
  29.06.2021   Zoom   11:05 h   Adaptive Filters for GPS   Jan-Niklas Busse  



If you do not have a date for the exam yet please register in the online booking system (once the exam dates have been set). You can find the booking system here.




Link   Content  
    Current evaluation  
    Completed evaluations