PTOLEMY II - CiteSeerX

Using Vergil
2.2.2 Executing a Pre-Built Model: A Signal Processing Example
The very first example on the quick tour page is the model shown in figure 2.1. It creates a sinusoidal
signal, multiplies it by a sinusoidal carrier, adds noise, and then estimates the power spectrum. You
can execute this model in either of two ways. First, you can select Run Window in the View menu, and
then click on Go. The result is shown in figure 2.4. The upper plot shows the spectrum of the timedomain
signal shown in the lower plot. Note the four peaks, which indicate the modulated sinusoid. In
the run window you can adjust the frequencies of the signal and the carrier as well as the amount of
noise. These can also be adjusted in the block diagram in figure 2.1 by double clicking on the bulleted
parameters near the upper right of the window.
The second alternative for running the model is to click on the run button in the toolbar, which is
indicated by a red triangle pointing to the right. If you use this alternative, then the two signal plots are
displayed in their own windows.
You can study the way the model is constructed in figure 2.1. Note the Expression actor in the middle,
whose icon indicates the expression being calculated: “signal*carrier + noise”. The identifiers
in this expression, signal, carrier, and noise refer to the input ports by name. The names of
FIGURE 2.3. The quick-tour page.
Heterogeneous Concurrent Modeling and Design 47