摘要:
A method is provided for processing a composite digital audio broadcast signal to mitigate intermittent interruptions in the reception of said digital audio broadcast signal. The method includes the steps of separating an analog modulated portion of the digital audio broadcast signal from a digitally modulated portion of the digital audio broadcast signal, producing a first plurality of audio frames having symbols representative of the analog modulated portion of the digital audio broadcast signal, and producing a second plurality of audio frames having symbols representative of the digitally modulated portion of the digital audio broadcast signal. The first plurality of audio frames is then combined with the second plurality of audio frames to produce a blended audio output. A method is also provided for transmitting a composite digital audio broadcast signal having an analog portion and a digital portion to mitigate intermittent interruptions in the reception of said digital audio broadcast signal. The method comprises the steps of arranging symbols representative of the digital portion of the digital audio broadcast signal into a plurality of audio frames, producing a plurality of modem frames, each of the modem frames including a predetermined number of the audio frames, and adding a frame synchronization signal to each of the modem frames. The modem frames are then transmitted along with the analog portion of the digital audio broadcast signal, with the analog portion being delayed by a time delay corresponding to an integral number of the modem frames. The invention also encompasses radio receivers and transmitters which process signals according to the above method.
摘要:
A system (100) for mitigating intermittent interruptions in an audio radio broadcast system is provided wherein a primary radio signal and a redundant radio signal are transmitted from a transmitter subsystem (120) and received by a receiver subsystem (140). The output (112) of an audio source (110) is coupled to a modulator (160) for modulating a radio frequency signal (162) for coupling to a transmit antenna (172). A second output (114) of audio source (110) is coupled to a delay circuit (116), for adding a predetermined time delay thereto. The delayed audio source signal is coupled to a modulator (164) for modulating a second radio frequency signal (166) that is also coupled to the transmit antenna (172). The receiver subsystem (140) receives both the primary radio signal and the delayed redundant radio signal and couples each to a respective demodulator (180, 182). At least demodulator (180) includes a circuit (181) for determining the degradation in the primary radio signal and provides a quality measurement output signal (186) to a blend control circuit (190). The recovered primary audio signal from demodulator (180) is coupled to a second delay circuit (184), the time delay of second delay circuit (184) being substantially equal to the time delay of delay circuit (116). The audio output from delay circuit (184) and the redundant audio output from demodulator (182) are coupled to a blending subsystem (135), wherein each is combined with a weighting factor and then combined together to form a composite audio signal for coupling to the audio output circuit (150).