Digital Signal Processing 1


Lab course Winter Term



project 3





1. Interpolation in frequency domain

▪ Create a sine signal with one period consisting of 10 samples (Fs = 10Hz).


▪ Enhance the sine signal sampling by using frequency domain interpolation using a variable factor L (e.g. L = 5) yielding in a sampling frequency of Fs*M.



2. Up-sampling in time domain


▪ Up-sampling is the method to artificially increase the sampling rate by inserting zeros between the sample values of the original discrete signal.


▪ Enhance the sine signal sampling of section 1 by using time domain up-sampling using a variable factor L (e.g. L=5).



3. Interpolation in time domain


▪ Explain why time domain interpolation requires low pass filtering of the up-sampled signal.


▪ Design a corresponding low pass filter


▪ MATLAB commands: fir1, filter



4. Down-sampling in time domain

▪ Reduce the number of samples by a variable factor M (e.g. M=3)




Applied Image & Signal Processing

Informationstechnik & System-Management 1/ 2


Salzburg University of Applied Sciences



Digital Signal Processing 1


Lab course Winter Term


Home project: Resample demo


▪ Implement a demo script demoresample.m which shows the effects of up-sampling/interpolation and down-sampling/decimation.


▪ Generate a Fourier series (as in project 2) with variable series length [1 21], fixed signal frequency (5Hz), fixed sample frequency (100Hz), fixed amplitude (1) and fixed signal length (1sec).


▪ Provide two sliders for Up-sampling and down-sampling with factors [1 10].


▪ Use two checkboxes to enable interpolation and decimation.


▪ Use a 3×2 plot to show the following:


▪ Time-domain plots (1st column); two-sided linear spectrum (2nd column).


▪ Original Fourier series (1st row); up-sampled/interpolated signal (2nd row); down-sampled/decimated signal (3rd row);

▪ MATLAB files must have a header. Plots should be labeled and must have axis labeling.


▪ Required upload


▪ demoresample.m

Applied Image & Signal Processing

Informationstechnik & System-Management 2/ 2


Salzburg University of Applied Sciences