Let's run our first exercise by means of the graphical programming environment called LTPDA Workbench. To start the workbench, issue the following command on the MATLAB terminal, or click on the "LTPDA Workbench" button on the launch bay.
LTPDAworkbench
Now let's go ahead an create a new pipeline, or analysis diagram. There are many ways to do this: hit ctrl-n (cmd-n on Mac OS X), or select "New Pipeline" from the "Pipeline" menu. (For more details on this and the other commands using the workbench environment please refert to the appropriate section of the user manual.)
Let's use the command "Pipeline -> Rename Pipeline" to give this diagram a more significant name, such for instance "LTPDA Training Session PSD1". You should see a window like the one below:
The idea of the first exercise is the following:
Well, let's do it.
You can also use the "Quick Block" dialog. This is especially useful if you know the name of the block you are looking for. To open the Quick Block dialog, hit ctrl-b (cmd-b on Mac OS X) on the Canvas.
To get the ao constructor block we want, just start typing in the "method" edit field. Once the block ao is top of the list, just hit enter to add it to the canvas. You can also double-click on the block list to add any of the blocks in the list.
Then let's choose, from the "Parameters" drop-down list, the "From Waveform option" set, and hit "Set" to assign this choice to the currently selected ao constructor block.
We can now tune the parameters of the ao constructor: in particular, let's double click on the first parameter line, within the "Value" colum, so we can choose "noise" from the drop-down list that will appear. If needed, more help can be found here.
Then let's make the time series last longer by selecting the number of seconds nsecs value to 1000.
Eventually, we set the units of the noise to be meters by selecting the "unit" parameter and entering 'm'.
Now let's go ahead and search within the libray for the psd method on the ao class. To do that, just click on the "Library" button on the top left of the screen, and type the word in the "search" box. Once we found the psd method, let's add it to the diagram, and then connect its input to the output of the ao constructor block.
The next step is choosing the parameters. After selecting the "Default" set and clicking "Set", we can proceed and modify the parameters. Let's discuss about the parameters and their meaning:
If the user does not specify any value for the parameters, the routine applies the default values. When called within the LTPDAworkbench graphical environment, the default parameters are explicitly shown after selecting the "Default" set and clicking "Set".
In this case, we will use the default parameters:
What's remaining is just plotting the calculated square root of the psd of the inout white noise. Just add the iplot block and connect it ... and why not adding a new iplot to look at the face of the input time-series signal?
So at the end we should have a situation like the following:
Notice that we also renamed the individual blocks, by double clicking on them and typing in the informations, and we changed the zoom amount by using the mouse scroll wheel or the commands available under the "View" menu.
Then we can execute the diagram, by clicking on the "Run" button on the bottom center, and the calculation should end up with 2 figures. The second one should be the following:
Please notice: