Digital Envelope Detection: The Good, the Bad, and the Ugly [Tips and Tricks]

During a recent consulting job to analyze acoustic telemetry signals transmitted by a deep-sea drill pipe, I was forced to investigate a process called digital envelope detection. This process is used to estimate the instantaneous magnitude of a zero-mean fluctuating-amplitude digital signal. While much tutorial information regarding envelope detection is available, that information is spread out over a number of communications textbooks and many websites. The purpose of this article is to collect and describe various digital envelope detection methods in one concise and consistent lesson.