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SD2125 Signals and Mechanical Systems 6.0 credits

The fundamental part gives knowledge of the theoretical background of signal analysis, e.g., Fourier analysis, FFT, DFT, correlation, signals and linear systems and the Z-transforms and digital filters. In the application part signal analysis is used in some important applications.

Choose semester and course offering to see current information and more about the course, such as course syllabus, study period, and application information.

Headings with content from the Course syllabus SD2125 (Autumn 2024–) are denoted with an asterisk ( )

Content and learning outcomes

Course contents

Fundamental part: Amplitude characterisation, classification of signals, Fourier analysis and Laplace transforms in signal analysis, discrete signals (sampling, averaging, DFT, FFT, correlation methods, signals and linear systems - frequency response functions, power spectral density, frequency analysis with FFT, frequency analysis with filters, Z-transforms and digital filtering.

The students will get practical training in using the theoretical concepts and signal analysis methods by computer exercises.

Application part: Control of mechanical systems, machine monitoring, active control of sound and vibration. In the computer exercise in machine monitoring it is shown how vibration measurements can be used to detect defects in bearings. In the laboratory exercise on active control of sound digital filtering is used to attenuate sound in a duct.

Intended learning outcomes

The aim of the first part of the course is to give the students knowledge about the theoretical foundations of signal analysis, and ability to apply this knowledge for analysis of mechanical systems. The aim of the application part of the course is to acquire knowledge and practical ability in important methods in analysis of mechanical systems.

The student should after finishing the course be able to:

  • Use a signal analyser (FFT-analyser) and be able to choose the measurement setup: frequency range, length of time record, time windows, number of averages etc.
  • Perform signal analysis on measured time record in Matlab.
  • Choose appropriate signal analysis methodology for a given problem. For example choosing between time or frequency domain analysis, one-channel or multi-channel analysis, different types of filtering etc.
  • Interpret results from different types of signal analysis, for instance spectra, correlation functions or frequency response functions.
  • Be able to extract information about the character of the studied signal such as periodicity, time delays and linearity.

Literature and preparations

Specific prerequisites

Completed courses in single-variable analysis, 7.5 credits, multivariable analysis, 7.5 credits, algebra and geometry, 7.5 credits, and differential equations, 6 credits.

English B / English 6

Recommended prerequisites

SD1120 Sound and Vibration 9.0 credits


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Examination and completion

If the course is discontinued, students may request to be examined during the following two academic years.

Grading scale

A, B, C, D, E, FX, F


  • LAB1 - Laboratory Works, 2.0 credits, grading scale: P, F
  • LAB2 - Laboratory Works, 1.0 credits, grading scale: P, F
  • TEN1 - Control Test, 3.0 credits, grading scale: A, B, C, D, E, FX, F

Based on recommendation from KTH’s coordinator for disabilities, the examiner will decide how to adapt an examination for students with documented disability.

The examiner may apply another examination format when re-examining individual students.

Other requirements for final grade

Written examination (TEN1; 3 university credits). Computer exercises (LAB1; 2 university credits), Laboratory exercise (LAB2; 1 university credits).

Opportunity to complete the requirements via supplementary examination

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Opportunity to raise an approved grade via renewed examination

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Ethical approach

  • All members of a group are responsible for the group's work.
  • In any assessment, every student shall honestly disclose any help received and sources used.
  • In an oral assessment, every student shall be able to present and answer questions about the entire assignment and solution.

Further information

Course room in Canvas

Registered students find further information about the implementation of the course in the course room in Canvas. A link to the course room can be found under the tab Studies in the Personal menu at the start of the course.

Offered by

Main field of study

This course does not belong to any Main field of study.

Education cycle

Second cycle

Add-on studies

SD2140 Vibroacoustics
SD2165 Acoustical Measurements
SD2150 Experimental Structure Dynamics
SD2155 Flow Acoustics
SD2175 Numerical Methods for Acoustics and Vibration
SD2180 Non-Linear Acoustics
SD2190 Vehicle Acoustics and Vibration


Elias Alfredo Zea Marcano (