June 15, 2014
June 15, 2014
June 18, 2014
24.290.1 - 24.290.11
Common Pitfalls in Communications Systems SimulationAbstract: Simulation plays an important role in undergraduate communications systemseducation. Using a numerical computing language, students can put in practice communicationsand signals and systems theory, easily plot signals and their spectra, and predict the performanceof eventual hardware implementations. Simulation, especially when coupled with a scriptinglanguage, is also a very good environment for learning and practicing skills such as systemdebugging and performance evaluation.In this paper, we present some of the most common pitfalls students face when simulatingcommunications systems. Over the years, we have found that students consistently make thesame mistakes and have difficulty grasping and mastering the same concepts. This presents anexcellent opportunity to develop teaching and learning strategies that address these specificpitfalls, especially given that they form a relatively small set. The pitfalls we have found aremost common are: The role of the Nyquist frequency. This frequency has to be calculated in advance, based on the highest frequency that will be simulated. Even in a system as simple as an envelope detector, the non-linear operation involved introduces frequencies of (theoretically) infinite frequency, making the choice of Nyquist frequency difficult. Simulating a system where input and output signals have different sampling frequencies than that required in simulation. This happens often when the signal source or sink is an external device, such as a computer’s sound card. Use of spectra to diagnose problems such as incorrect simulation parameters or faulty system design. Moreover, students find it hard to switch between time and frequency domains and use the most appropriate to diagnose and solve the problem at hand. Filter design also presents difficulties to most students. The filter order and the size of the transition bands interact in non-trivial ways. However, the most common pitfall is that students are often unaware that the filters they are using are not appropriate for their purpose, usually because they don’t have enough out-of-band rejection.Along with more detailed descriptions of these and other common pitfalls, we present teachingand learning strategies we have developed to address them, with an assessment of their efficacy.
Bazdresch, M. (2014, June), Common Pitfalls in Communications Systems Simulation Paper presented at 2014 ASEE Annual Conference & Exposition, Indianapolis, Indiana. 10.18260/1-2--20181
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