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This paper discusses the teaching of Fourier Series concepts in undergraduate Electrical Engineering education with the help of an Android application, especially developed to that end. In order to better understand the links and implications, some of the basic Fourier series theory is briefly reviewed. The Android application has an easy-to-use, friendly interface, conceived to help undergraduate students test and assess the Fourier series expansions on a typical set of signals. The application also allows the students to control the total approximation error and the number of terms/harmonics used in the expansions. It has been found a very useful learning resource in the Fourier series context.

This paper presents a no-reference model for monitoring the voice quality experienced by users in VoIP services. The proposed model is based on the E-Model, which is adapted from Recommendation ITU-T G.107 for this purpose. A calibration function was determined for relevant codecs under different packet loss conditions. Extensive field testing was carried out to validate the proposed model at PT Inovação Labs (Portugal). The results show that the mean opinion score (MOS) obtained from the proposed model match class C2 of conformance tests defined in ITU-T Recommendation P.564. The QoE model described in this paper was implemented in a VoIP QoE probe and is currently fully operational at Portugal Telecom.