DSP Blockset

Part 1 -- Creating a Signal with Added Noise

In this section of the tutorial, you will create a signal with added noise. Later in the tutorial, you will filter this signal with a fixed-point filter that you design with the Filter Realization Wizard.

1. Type

• load mtlb

  soundsc(mtlb,Fs)

1. at the MATLAB command line. You should hear a voice say "MATLAB." This is the signal to which you will add noise.

2. Create a noise signal by typing

• noise = cos(2*pi*3*Fs/8*(0:length(mtlb)-1)/Fs)';

1. at the command line. You can hear the noise signal by typing

   • soundsc(noise,Fs)

3. Add the noise to the original signal by typing

• u = mtlb + noise;

1. at the command line.

4. Scale the signal with noise by typing

• u = u/max(abs(u));

1. at the command line. You scale the signal to try to avoid overflows later on. You can hear the scaled signal with noise by typing

   • soundsc(u,Fs)

5. View the scaled signal with noise by typing

• specgram(u,256,Fs);colorbar

1. at the command line.

The spectrogram will appear as follows.

In the spectrogram, you can see the noise signal as a horizontal line at about 2800 Hz, which is equal to 3*Fs/8.

Designing and Implementing a Fixed-Point Filter

Part 2 -- Creating a Fixed-Point Filter with the Filter Realization Wizard