AMSTEREO
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 systems, promoted principally by American broadcast engineer Leonard R. Kahn; and quadrature amplitude modulation multiplexing systems .The above text is a snippet from Wikipedia: AM stereo
and as such is available under the Creative Commons Attribution/Share-Alike License.