Harmonic distortion. Genesis to revelation?

With the recent developments in personal computers and their widespread use in exploiting the Internet, there has been a resulting demand for high speed communications. The use of conventional telephone networks poses a significant problem for error-free data transmission by modem. Central to these transmission speed limitations is the isolation transformer and its effect on the rate obtained in such signal transfer. In particular, due to their nonlinear transfer function, transformer core materials produce harmonic distortion terms which corrupt the transmitted data. However, harmonic distortion and the way it influences bit error rate is not universally understood. This paper discusses this relationship and evaluates how the magnetic hysteresis loop profile of the core material affects the magnitude and phase of the harmonic terms. It goes on to study how the alloy composition and structure influences such terms, and demonstrates how the heat treatment and manufacture of the laminations changes the overall distortion effect. Finally, the paper offers strategies for improving loop shape and consequently the distortion contribution of the isolation transformer