This paper is a brief tutorial on methods for using modulated signals in feedback loops, and especially of the different methods and trade offs used for demodulating those signals to get information for the control loop. Modulation and demodulation are often understood as being part of communication theory, but the methods used to demodulate control signals can have a dramatic effect on the amount of delay, noise, and nonlinearity that gets passed from the desired control information into the feedback loop itself. In this tutorial, we hope to give a more fundamental understanding of how to properly use demodulation to minimize “sensor noise” before it ever enters into the loop.
Peer Reviewed Paper
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