Method of controlling filter bandwidth in a radio receiver for a duplicative broadcast signal

摘要

A radio receiver performs a tune to a target frequency channel to recover a main audio program signal from a duplicative signal wherein the duplicative signal includes a primary signal and a backup signal both containing the main program audio signal. The backup signal is provided in a center portion of the target frequency channel and the primary signal is provided in an upper and lower sideband portion of the target frequency channel. The backup signal contains an identifying data which relates to the presence of the primary signal. The method includes tuning to the target frequency channel. The receiver filters the target frequency channel using a narrow bandwidth. A determination is made whether the identifying data is present. If the identifying data is present, then the main audio program is retrieved from the primary signal using a wide bandwidth, otherwise the narrow bandwidth is used to retrieve the main audio program from the backup signal.