Assignment:
Assume the signal consist of a sum of 3 sinusoids (sine functions, no phase delay). One sine is at 50hz, the second is at 60hz, and the third is at 75 Hz. The 50hz and 60hz sines have a peak magnitude of 1, the 75hz sine has a peak magnitude of .1. Assume the combined signal is sampled at 240hz, and 256 samples of the signal are available.
Perform the following using a rectangular window and a von Hann (Hanning) window.
[1] For the two windows, window the received signal (multiply received signal by the time domain), using a window length of 64, 128, and 256 (a total of 6 windowed signals). For the smaller length windows, you will need to zero pad the window until its length equals 256.
[2] For each windowed signal above, perform a 256 pt FFT (using the fft function in matlab).
[3] Compare the frequency response magnitudes for each of the responses above (will need to plot on a logarithmic scale). Comment on the observations noting things such as if the signals are resolvable, the size of the side lobes, etc. How does the FT of a rectangular window explain the trends in the graphs?