wiki:DSP/Interpolation

Version 2 (modified by dlambros, 9 years ago) ( diff )

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Table of Contents

  1. Interpolation Tutorials
    1. Introduction
    2. Materials Required
    3. Installing GNURadio
    4. Interpolation of a Sinusoidal Wave with GNURadio
    5. Interpolation of a .WAV File with GNURadio
    6. Interpolation of a Sinusoidal Wave with Octave

Interpolation Tutorials

Introduction

Interpolation, also known as upsampling in the case of Digital Signal Processing, is a process that provides an approximation of the signal that would have been obtained if it had been sampled at a higher sample rate.

Before continuing with this tutorial for further reading for understanding Interpolation read the following resources:

Materials Required

Installing GNURadio

If running on a Ubuntu or Debian distribution of Linux use the following command for installation: 

sudo apt-get install gnuradio

For other OS's follow the instructions from this ​guide.

Interpolation of a Sinusoidal Wave with GNURadio

In GNURadio on your computer implement the following flow chart to obtain the following FFT and Scope Plots:

Next add a Interpolation FIR Filter with an Interpolation of 3 as seen below:


Verify that the Scope and FFT plots are:

The waveforms can be seen with 3 zeros inserted from the Interpolation FIR Filter between every sampled point. Next apply a Low Pass Filter as seen below to smooth out the waveform.

Verify that the smoothed out signal plots resemble:

Interpolation of a .WAV File with GNURadio

For the following download the .WAV File and listen to the audio file. Then set up the following flowgraph in GNURadio:

Go back to the original .WAV File and listen to the audio. Then listen to the output file and notice the difference and effects of upsampling an audio sample.

Interpolation of a Sinusoidal Wave with Octave

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