Changes between Initial Version and Version 1 of DSP/Interpolation


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Jun 2, 2015, 12:25:49 AM (9 years ago)
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dlambros
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  • DSP/Interpolation

    v1 v1  
     1[[TOC(DSP/Interpolation*, depth=3)]]
     2
     3= Interpolation Tutorials =
     4
     5== Introduction ==
     6Interpolation, 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.[[BR]]
     7
     8Before continuing with this tutorial for further reading for understanding Interpolation read the following resources:
     9* [http://dspguru.com/dsp/faqs/multirate/interpolation DSPGuru - Interpolation]
     10* [http://en.wikipedia.org/wiki/Upsampling Wiki - Upsampling]
     11== Materials Required ==
     12* [http://www.orbit-lab.org/userManagement/register Orbit Account]
     13* Installation of GNURadio
     14* Reservation on Orbit Lab
     15* WAV File 
     16== Installing GNURadio ==
     17If running on a Ubuntu or Debian distribution of Linux use the following command for installation:
     18{{{
     19sudo apt-get install gnuradio
     20}}}
     21
     22For other OS's follow the instructions from this [http://gnuradio.org/redmine/projects/gnuradio/wiki/InstallingGR guide].
     23== Interpolation of a Sinusoidal Wave with GNURadio ==
     24In GNURadio on your computer implement the following flow chart to obtain the following FFT and Scope Plots:
     25[[Image(img1.png)]]
     26[[Image(img2.png)]][[Image(img3.png)]]
     27
     28Next add a Interpolation FIR Filter with an Interpolation of 3 as seen below:
     29[[Image(img4.png)]] [[BR]]
     30
     31Verify that the Scope and FFT plots are:
     32[[Image(img5.png)]][[Image(img6.png)]]
     33
     34The 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.
     35[[Image(img7.png)]]
     36
     37Verify that the smoothed out signal plots resemble:
     38[[Image(img8.png)]] [[Image(img9.png)]]
     39== Interpolation of a .WAV File with GNURadio ==
     40For the following download the .WAV File and listen to the audio file. Then set up the following flowgraph in GNURadio:
     41[[Image(img10.png)]]
     42Go 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.
     43== Interpolation of a Sinusoidal Wave with Octave ==
     44