In this Optisystem introductory tutorial video, we will be exploring how to set up the pseudo-random bit sequence generator in Optisystem.
About The Component
The pseudo-random bit sequence can be used to generate a binary sequence of pseudo-random bits. This bit sequence can be connected to a binary sequence visualizer, allowing you to see the output bit sequence.
When you double-click the block, the main properties are displayed. By double-clicking next to ‘bit rate,’ you can change the bit rate of the block to base it on other parameters or to derive its value from a function. Pressing ‘Evaluate’ lets you check the current value of the bit rate. If you wish to change the bit rate defined for the entire project, double-click on your workspace, and the global parameters window will pop up. In this window, you can change the bit rate for the project, as well as other global parameters. Returning to the pseudo-random bit sequence generator and pressing ‘evaluate script,’ you will see that the bit rate has been updated.
With the operation mode set to ‘probability,’ the OptiSystem sequence generator will produce a random output, and the probability of generating a ‘1’ will be based on the Mark probability. The length of the sequence generated will match the global parameter ‘sequence length.’
Before testing the bit sequence generator, I will change the number of leading and trailing zeros to observe the output more easily. As you can see, the output of the generator reflects a 0.5 probability of generating a ‘1’ at the output.
Now, I would like to try changing the mark probability to a lower value. After recalculating the project a few times and examining the visualizer, we can observe that the probability of generating a ‘1’ is now much lower.
Going back into the pseudo-random bit sequence generator and accessing the ‘random numbers’ tab, we can choose to either generate a random seed each time or define our own seed. A seed is a number used to initialize a pseudo-random generator. So, if we uncheck the ‘generate random seed’ box and instead choose our own random seed index, this means every time we run the generator, we should receive the same set of random numbers because the seed used to generate them is the same.
Running the program twice, the result is as expected. The set of random bits is the same because we used the same seed both times. Switching back to select the ‘generate random seed’ box, we should expect a different result this time, as we are not using the same seed. The ‘Different each iteration’ box can be used to generate a different random seed each time the project is run for multiple iterations. Upon recalculating the project, we can see that the result is different because the seed has changed.
Going back into the bit sequence generator and changing the operation mode to ‘order’ will cause the pseudo-random bit sequence generator to generate a random bit sequence with a period of 2 to the power of the order minus 1.
Clicking on ‘order,’ you can change the value to make it dependent on other layout parameters. Pressing ‘evaluate,’ you can see its current value. After calculating the project and checking the binary sequence visualizer, the output shows. Changing the output range to a larger number, we can see that the sequence ends at 1024 bits. Given an order of 10, this means that the period of the sequence would be 1023 bits. Going back into the OptiSystem sequence generator and changing the operation mode to ‘alternate’ will cause the output sequence to alternate between ones and zeroes. Changing the operation mode to ‘ones’ will cause it to output all ones while changing it to ‘zeros’ will cause it to output all zeroes.
Count on Optiwave’s Expertise
OptiSystem’s pseudo-random bit sequence generator is a crucial tool for simulating and analyzing optical communication systems. Its flexibility in adjusting parameters like bit rate, operation modes, and seed generation makes it an invaluable asset for researchers and engineers. Optiwave’s commitment to providing advanced simulation tools and support ensures that users have access to top-tier resources for their optical system design needs.
Want to learn more? Contact us at support@optiwave.com