AM Stereo

AM stereo is a term given to a series of mutually incompatible techniques for wireless radio broadcasting stereo audio in the AM band in a manner that is compatible with standard AM receivers. There are two main classes of systems: independent sideband (ISB) systems, promoted principally by American broadcast engineer Leonard Kahn; and quadrature amplitude modulation (QAM) multiplexing systems (conceptually closer to FM stereo).

Read more about AM Stereo:  History, Broadcasting Systems, Adoption in The United States, Global Adoption, Current Status, Surround Sound, Decline in Use