The formal name used nowadays (one of them, anyhow) is Quadrature Detector. It's a scheme so elegant that grasping the simple mechanics of it demystifies some

The formal name used nowadays (one of them, anyhow) is Quadrature Detector. It's a scheme so elegant that grasping the simple mechanics of it demystifies some of the core concepts of Signal Processing. The QEX series "A Software-Defined Radio for the Masses"[1] is usually offered as the work that popularized this approach. The Motorola patent[2] that cites Dan Tayloe as inventor expired in 2018 [3]. [1] https://sites.google.com/site/thesdrinstitute/A-Software-Defined-Radio-for-the-Masses https://sites.google.com/site/thesdrinstitute/A-Software-Def... [2] https://patents.google.com/patent/US6230000 https://patents.google.com/patent/US6230000 [3] https://www.eevblog.com/forum/rf-microwave/patent-expiration-tayloe-mixer-quadrature-sampling-detector/ https://www.eevblog.com/forum/rf-microwave/patent-expiration... It's quite the rabbit hole and if you dive in you'll end up with a HAM license and a workshop full of instruments and soldering tools.