Compensation on Nonlinearities in Transducers

Martin Rune Andersen

AbstractThis thesis is concerned with the topic of compensation algorithms for the nonlinearities in transducers for use in hifi-loudspeaker. The thesis contains a examination of the general ideal loudspeaker model. Furthermore, nonlinearities that influences the performance of the loudspeaker are described, and measurement are done on what they does to the loudspeaker.

The loudspeaker model is from here transformed into the digital domain, in preparation for constructing a control system later. In order to make this model complete, appropriate functions are fitted to the nonlinearities and added to the model.

Furthermore, a text based toolbox for Matlab is made for simulations and evaluations of di erent properties in both the loudspeaker and in the upcoming compensation algorithm.

Finally, two interesting feedforward controller systems are presented. The first is the "state space" compensator and the second is the "Mirror filter" derived by Wolfgang Klippel. Later research has shown that they are of same controller type.

In Danish:

Denne rapport omhandler emnet kompenserings algoritmer for ikke-lineariteter i transducere til brug i hi-fi højttalere. Rapporten indeholder en gennemgang af den generelle ideelle højttaler model. Yderligere er ikke-lineariteterne der forringer ydelsen af højttaleren beskrevet og målinger, omkring hvad det gør ved denne, er foretaget.

Herfra overføres højttaler modellen til det digitale domæne med henblik på senere at konstruere et regulering system til denne. Og for at gøre modellen komplet i forhold til højttaleren, tilpasses en passende funktion til ikke-lineariteterne så disse kan inkluderes.

Desuden præsenteres en Matlab toolbox til hjælp med at simulere og evaluere de forskellige egenskaber i både højttalere og også i de senere kompenseringsalgoritmer.

Til sidst gennemgås to interessante prekompensering algoritmer. Den ene er "state-space" kompensatoren og den anden er Wolfgang Klippels "Mirror filter". Ved senere tids forskning har det dog vist sig, at disse to er af samme type reguleringssystem.
TypeMaster's thesis [Industrial collaboration]
PublisherInformatics and Mathematical Modelling, Technical University of Denmark, DTU
AddressRichard Petersens Plads, Building 321, DK-2800 Kgs. Lyngby
NoteSupervised by assoc. prof. Ole Winther and assoc. prof. Jan Larsen. In corporation with Ørsted.DTU and Oticon a/s
Electronic version(s)[pdf]
BibTeX data [bibtex]
IMM Group(s)Intelligent Signal Processing

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