The Gaussian pulse generator generates an electrical Gaussian pulse pulse. In this video we will be looking at the settings of the Gaussian pulse generator and will observe the effects of changing different parameters.

Using the Component

The Gaussian pulse generator generates an electrical Gaussian pulsed signal. For this example, we will use a bit sequence generator at the input of the pulse generator to create the bit sequence that will determine the location of the pulses. We will be using a fork, 2 pulse generators and comparing them in an oscilloscope so we can easily observe the effects of changing different parameters. Clicking the bit sequence generator, we can see the bit sequence we will be using. Calculating the project and clicking on the visualizer allows you to see the results. As you can see, the output is not quite what you may have expected because the pulses are at a width where they overlap and end up interfering with each other.

 Double clicking on our pulse generator block we can see the properties of the pulse generator. One parameter that will help reduce the overlap is selecting truncated. Truncating the pulses will reduced or eliminate overlap. Double clicking the oscilloscope we can see the modified signal up top and the original signal below. We observe that there is less overlap now that the signal is truncated.

Another way to reduce overlap is to change width value. Changing the value of width to 0.3 will make each pulse have a FWHM width of 0.3 of a bit. Running the program, we can see that the pulse became narrower. Modifying the settings of both blocks to make them identical again we can see what the next change will do. In the format for pulse range box, we can change the pulse to get its properties from DC bias and amplitude rather then defining the minimum and maximum values. The maximum value will now be equal to DC bias plus amplitude and the minimum value will be equal to DC bias minus the amplitude. In the visualizer we can see that the pulses now have a DC bias of -1 and an amplitude of 2 as expected.

 Going back into the properties of the pulse generator we can observe the effect that changing the order has on pulse. running the program, we can see that with a higher order function, the pulses increases to the maximum value and decreases to the minimum value more quickly.

 Changing the value of position provides a phase shift of whatever value entered.  A position value of 0.5 should give a phase shift of 0.5 bits to the right. Checking the visualizer, we can see that the pulses have been shifted as expected.

Deselecting the external input bit sequence box will make the pulses stop being controlled by the bit sequence present at the input and instead pulses will be defined by the generating pulse parameters section. The location of pulses can be changed by changing the values in pulse peak locations. With the values added we should now see pulses at 1, 3, 5 and 9 nano seconds.

Going to the visualizer and changing the range we can see that the pulses occur where we expect them to be. you will also notice that the blocks are no longer connected to the bit sequence generator because they are no longer dependent on it.

Going back into the properties we can see that this current bit sequence it set to repeat every Time window. The value of time window can be edited by clicking beside it. Here we can change the repeat cycle to be dependent on other parameters or be defined by a function. We will leave it set as time window and pressing evaluate we can see what the value of time window currently is. Time window is a global parameter and can be seen above. If we want it to repeat more often, we can divide the value of time window by 10 to make it repeat more often. double clicking anywhere on the work space brings up the global parameters window. In this window it is possible to change the value of time window as well as any other global parameters, however we will leave it the same.

 Running it, we can see that the signal repeats more often as expected. The FWHM parameter controls the full width at half maximum. Pressing evaluate script we can see what the current value of this is.  We can change the FWHM value to make it smaller and see what the effect will be. with a smaller FWHM value we can see that the pulse width is smaller. Putting a larger value in for FWHM will make the pulse width wider. The value for FWHM is also dependent on sample rate. Going into the global parameters window we can change the sample rate as well. Making the sample rate smaller will in turn make the FWHM width wider. Calculating the project, we can see that the result is as expected and the pulse width is wider. we also notice the pulses are now starting to overlap. Going into the properties we can change truncation width to prevent overlap. pressing evaluate we can see the truncation width is a lot larger than our FWHM width so truncation will not have any effect with its current settings. Dividing truncation width by 100 will reduce the truncation width enough to reduce the width of the pulse and get rid of the pulses interfering with each other. Calculating the project, we can see that the pulses are now truncated to prevent them interfering with each other