The quadrature modulatio method of AM stereo broadcasting utilizes normal double sideband AM transmission to convey the sum signal, and an added pair of sideband phasors, the sum of which is quadrature with the carrier phasor, to convey the difference signal. The system described here features processing of the (A+B) and (A-B) channels to insure optimum compatibility and stereophony. The resulting spectrum, effects on existing receivers, and performance of stereo receivers designed for the system are discussed. The application o- this method to a 250 w transmitter and to a high power broadcast transmitter presented some implementation problems. The means of overcoming these are discussed and a description of conversion equipment is given.
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