Spectral Analysis for Signal Detection and Classification: Reducing Variance and Extracting Features

Isabella Reinhold

Research output: ThesisDoctoral Thesis (compilation)

379 Downloads (Pure)


Spectral analysis encompasses several powerful signal processing methods. The papers in this thesis present methods for finding good spectral representations, and methods both for stationary and non-stationary signals are considered. Stationary methods can be used for real-time evaluation, analysing shorter segments of an incoming signal, while non-stationary methods can be used to analyse the instantaneous frequencies of fully recorded signals. All the presented methods aim to produce spectral representations that have high resolution and are easy to interpret. Such representations allow for detection of individual signal components in multi-component signals, as well as separation of close signal components. This makes feature extraction in the spectral representation possible, relevant features include the frequency or instantaneous frequency of components, the number of components in the signal, and the time duration of the components. Two methods that extract some of these features automatically for two types of signals are presented in this thesis. One adapted to signals with two longer duration frequency modulated components that detects the instantaneous frequencies and cross-terms in the Wigner-Ville distribution, the other for signals with an unknown number of short duration oscillations that detects the instantaneous frequencies in a reassigned spectrogram. This thesis also presents two multitaper methods that reduce the influence of noise on the spectral representations. One is designed for stationary signals and the other for non-stationary signals with multiple short duration oscillations. Applications for the methods presented in this thesis include several within medicine, e.g. diagnosis from analysis of heart rate variability, improved ultrasound resolution, and interpretation of brain activity from the electroencephalogram.
Translated title of the contributionSpektralanalys för detektion och klassificering av signaler: Minska varians och extrahera egenskaper
Original languageEnglish
  • Sandsten, Maria, Supervisor
  • Starkhammar, Josefin, Assistant supervisor
  • Jakobsson, Andreas, Assistant supervisor
Award date2021 May 19
Place of PublicationLund
ISBN (Print)978-91-7895-803-0
ISBN (electronic) 978-91-7895-804-7
Publication statusPublished - 2021 Apr 23

Bibliographical note

Defence details
Date: 2021-05-19
Time: 13:15
Place: Lecture hall MH:Riesz, Centre of Mathematical Sciences, Sölvegatan 18, Faculty of Engineering LTH, Lund University, Lund
External reviewer(s)
Name: Aviyente, Selin
Title: Prof.
Affiliation: Michigan State University, USA

Subject classification (UKÄ)

  • Electrical Engineering, Electronic Engineering, Information Engineering

Free keywords

  • Instantaneous frequency
  • Multitaper
  • Signal resolution
  • Reassignment method
  • Time-frequency analysis


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