Matlab basic issues: Simulink Scope settings

For using the scope correctly, we have to know how to setup scope.

For the first setting window, we often need to change the number of axes to add more curves to watch in the scope.

If you want to show the legends, you can select it.

Most importantly, the sampling setting is helpful. When I use continuous-time vco to do some simulations, I change its quiescent frequency(center frequency) to high like 1000. The scope can’t show correct sinusoidal waves. It only allows me to set the frequency to show 3-5 cycles in the simulation time. This issue is related to the sampling setting in scope. It has two options: sampling or decimation. If you select sampling, you have to type smaller sampling time period than the input signal period which goes into scope for getting a good waveform. This is the rule of sampling theory. 

If you use decimation, your sampling time will be decimation number(which you type in)*input signal period. 

1. Scope setting window

Next figure is the axis window. This one is easier to understand. If you think the signal showing in scope is too big, which means you amplitude touches the top edge, you can use this setting to give a larger amplitude margin in scope.

2. Scope Axis window

The last one figure is also important. One issue I faced is that I simulate for a long time and supposed to get a lot of points out. But the scope only shows last range of data. This is because the scope limits the saving data points in default. So every time, if you use scope , it is better to deselect the “limit data points to last”.

Scope data history window

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