We are huge fans of the Goertzel DTFT for frequency domain analysis of power signals. This is a short paper by my colleague Dr. Kartikeya Tripathi from April 2010 written in the context of an instrument based on the ADE7878 IC from Analog Devices. He goes through the background and explains the issues in the first 3 sections and then presents the Goertzel IIR filter approach in Section 4. [read full article]