Abstract:

It has been observed that several students do not entirely comprehend and/or develop misconceptions regarding basic signal parameters such as power, average power and energy as well as essential signal processes such as convolution. More specifically, as far as the power and energy of a signal are concerned, student often find it difficult to understand what the instant and the average signal power actually are and what their practical significance is. Regarding convolution, most students fail to comprehend how the convolution integral can be calculated and, as a result, they cannot understand how convolution is actually used for the evaluation of the output of a linear and time invariant system.

The article describes a teaching approach whose aim to enhance the students’ conceptual understanding and dissolve misconceptions regarding signal power, energy and convolution.

Regarding power and energy, apart from proper comments and relevant exercises on the calculation of each quantity, what has been proved to be of help is the emphasis on the practical significance of average power in everyday application as well as the analogy (with regard to periodic signals in particular) between the instant power, average power and energy and the instant velocity, average, velocity and distance. The attention of students is also drawn to the issues associated with the definition of the above quantities for power and energy signals.

As far as convolution is concerned, the presentation of the process is based on the calculation of the convolution integral for two rectangular-pulse signals, since this integral is relatively easy to calculate. The next step is to fully explain how convolution is used for the calculation of a linear system’s output with the aid of the example mentioned above. Another example that can be of help (due to the relatively easy calculations involved) is the evaluation of the convolution integral for discrete signals.

The presentation of the power/energy and convolution concepts involved two 2-hour lectures in the framework of the “Telecommunication Systems” course at the Electrical & Electronic Engineering Educators Dept., School for Pedagogical & Technological Education (ASPETE), Athens, Greece. At the end of the second lecture, a short questionnaire was distributed to the students (answered by means of a 5-grade Likert scale) which showed that the applied approach was successful and well received.

Keywords:

Engineering Education, Electronic Engineering Education, Signals, Signal power, Signal energy, Convolution.