HW 13b

Installing Ubuntu

• VMWare Player
• Pre-compiled Ubuntu 8.10
  • U:vmplanet
  • P:vmplanet.net

GNU Radio + GNU Radio Companion

• GNU Radio Companion is installed with GNU Radio 3.2 and above. Install from the trunk. Synaptic Package Manager will only install 3.0.4
• GNU Radio Companion is the GUI for GNU Radio

Installing GNU Radio + GNU Radio Companion

• Grab the following files from mu/shared/class/engr/455/Adaptive Filter SDR Project/
  • grc.tar.gz
• http://gnuradio.org/trac/wiki/UbuntuInstall

SSB Demodulation

• Convert the *.auf files (and not the *.au files) using Audacity, note the sampling rate
• Wave source allows you to play the converted *.wav files
• Bandpass filter to single out the 3kHz (and get rid of the 1/f noise at the same time)
• Shift down to baseband with a cosine wave
• Low pass filter to single out the signal at the baseband (and to throw out the signal at +/- 2f)
• Use your favorite sink to hear/see the results

Octave Help

Octave Wiki

Adaptive Filter

% LMS algorithm for adaptive noise cancellation

h = zeros(N,1); mu = 1/(10*N*var(n)); %mu = 1.0; for k=N:Ls xk = n(k:-1:(k-N+1)); nhat(k) = h'*xk';

e(k) = - y(k) + nhat(k); h = h - mu*e(k)*xk'; %/(xk'*xk); % For the previous line. end

Questions

• Is h the adaptive filter coefficients? Yes!
• When you save the voice, is it an Nx1 or 1xN matrix?
• Whos (octave) will show all variables and their dimensions

Possibly promising links

dOxygen filters

Using GNU Radio with Octave

DttSP + GNU Radio