In the Name of God
University of Tehran
ECE Department
Introduction to Signal processing using Simulink environment
In this tutorial you will get familiar to use Simulink environment in
order to do different signal processing functions on a signal.
First we have to make a new Simulink model and set up the
environment. In order to do so, if you run the MATLAB environment, you
have to click on the Simulink icon:
Figure 1: Slimulink library
Then the Simulink library opens. On the library, you should click
new, and your first model will be created!
If you look at the Simulink library, there are many different blocks
you can put in your model. Here, we want to hear our own voice. This
microphone icon is inside the signal processing blockset which we are
usually going to work with. The path to this block is shown in figure 2. You
can drag and drop every icon from the library into your model.
Figure 2: Simulink library and model creation
Once you have done so, you can double click the icon you have
placed in your model to view or edit its settings. For our case, the
microphone:
Figure 3: block properties
You can simply click on the Help icon to see what each parameter does.
Here, the sample rate is the number of samples taken in every second,
the bits is the number of bits used to store your voice.
Now we want to get familiar with some signal processing functions and
the way we can implement them in Simulink:
Filter
Filters are the most well known signal processing functions. Filters
can be designed in Simulink by using the FDATool, this tool can be found
at:
Simulink library>signal processing blockset>filtering>filter designs
Or simply typing fdatool in the Matlab environment:
>>fdatool
Once the tool opens it looks like this:
You can enter the desired parameters in the specific place and push the
design filter button to design your filter. Then you can use the options on
the bottom left hand corner to export them to your model.
For example, the icon with [b,a] specifies the filter coefficients and the
second from the top (
environment.
) creates a filter model in the Simulink
Delay
One of the most important operations on a signal is delaying it, this
block can be found at:
Simulink library>signal processing blockset>signal operation
And looks like this
. This is the basic element if you want to
implement a filter manually.
Down or Upsampling
Another important signal processing operation is down
or up
sampling. Down sampling means that you discard some of the samples
you have. For example if you down sample the signal by two, this means
that you discard every other sample you have. So what's it good for? If
you do not have enough space to store all your samples, you just need half
memory space for storing! Of course it's not such a big deal, because you
first have to see if this operation damages your signal or not. These
operations can also be found at the same address as the delay block.
Other important blocks
There are some other useful important blocks that you may want to
use. The first one is the spectrum analyzer
which can be found at:
Simulink library>signal processing blockset>signal processing sinks
This block shows the frequency spectrum of the signal.
Finally you can find simple blocks such as add, multiply, saturate,…
blocks at:
Simulink library>Simulink>commonly used blocks.