EE 329: Laboratory 4
Spectral Analysis: Windowing and Spectrograms

1. Load the file chirp.au into Matlab with the command:

   x = auread('chirp.au');
   sound(x)

   The sampling rate for this data is 8192 samples per second. Listen to the sound, then view the FFT of the signal, and then view the spectrogram in Matlab with the command:

   specgram(x, 512, 8192, 256, 1);

   What is different between the FFT results and the spectrogram results? Use the help command in Matlab for more details about the arguments to the specgram command. Try to relate the specgram to the sound that you hear.

2. Download the Matlab program lab4.m to your account and run it. Try running the program with different amplitudes on the two signals and different frequencies. Explain why the windowing helps to identify the weaker signal. You might also try other windows -- type help signal for other window types.

3. Begin working on Homework 4.

Please submit a written report describing your results from items 1 and 2 by Wednesday, February 19. Thank you.