An apparatus comprises a digital input port configured to receive digital audio packets of main program service (MPS) audio; a modem operatively coupled to the digital port; an analog input port configured to receive an audio engineer society format (AES) audio signal that is a digitized version of the analog signal component of the frequency modulation (FM) hybrid radio signal; and an alignment unit configured to time-align the AES audio signal with the digital audio packets at the modem; wherein the modem is configured to generate the FM hybrid radio signal using the digital audio packets and the time-aligned AES audio signal.

Service modes specify how digital content is formatted in sidebands of an FM radio channel. In an improved service mode, encoded bits can be distributed between an in-band encoded component and a cross-band encoded component, where the encoded bits in the in-band encoded component are desynchronized by a specified duration with respect to the encoded bits in the cross-band encoded component. The encoded bits in the in-band encoded component can be allocated into frequency partitions that are used by a legacy service mode, such as MP1 or MP3, which can provide backward compatibility with the legacy service mode. The encoded bits in the cross-band encoded component can be allocated into frequency partitions that are not used by the legacy service mode, and are found in the opposite sideband, compared with the legacy service mode, which can provide time diversity within a single sideband.

Service modes specify how digital content is formatted in sidebands of an FM radio channel. In an improved service mode, encoded bits can be distributed between an in-band encoded component and a cross-band encoded component, where the encoded bits in the in-band encoded component are desynchronized by a specified duration with respect to the encoded bits in the cross-band encoded component. The encoded bits in the in-band encoded component can be allocated into frequency partitions that are used by a legacy service mode, such as MP1 or MP3, which can provide backward compatibility with the legacy service mode. The encoded bits in the cross-band encoded component can be allocated into frequency partitions that are not used by the legacy service mode, and are found in the opposite sideband, compared with the legacy service mode, which can provide time diversity within a single sideband.

An apparatus comprises a digital input port configured to receive digital audio packets of main program service (MPS) audio; a modem operatively coupled to the digital port; an analog input port configured to receive an audio engineer society format (AES) audio signal that is a digitized version of the analog signal component of the frequency modulation (FM) hybrid radio signal; and an alignment unit configured to time-align the AES audio signal with the digital audio packets at the modem; wherein the modem is configured to generate the FM hybrid radio signal using the digital audio packets and the time-aligned AES audio signal.

An apparatus comprises a digital input port configured to receive digital audio packets of main program service (MPS) audio; a modem operatively coupled to the digital port; an analog input port configured to receive an audio engineer society format (AES) audio signal that is a digitized version of the analog signal component of the frequency modulation (FM) hybrid radio signal; and an alignment unit configured to time-align the AES audio signal with the digital audio packets at the modem; wherein the modem is configured to generate the FM hybrid radio signal using the digital audio packets and the time-aligned AES audio signal.

An audio processor includes a detector configured to determine a correlation of first and second data corresponding to an analog FM component and an HD FM component, respectively, of a broadcast RF signal. A signal processor is configured to receive an input audio signal, to generate an analog FM audio signal and an HD FM audio signal therefrom and to control a relative timing of the analog FM audio signal and the HD FM audio signal based on the determined correlation. The signal processor may include a multiband limiter configured to generate a multiband limited audio signal responsive to the input audio signal, an HD FM audio processor configured to generate the HD FM audio signal responsive to the multiband limited audio signal, and an analog FM audio processor configured to generate the analog FM audio signal responsive to the multiband limited audio signal and to delay the analog FM audio signal responsive to the timing control signal.

An audio processor includes a detector configured to determine a correlation of first and second data corresponding to an analog FM component and an HD FM component, respectively, of a broadcast RF signal. A signal processor is configured to receive an input audio signal, to generate an analog FM audio signal and an HD FM audio signal therefrom and to control a relative timing of the analog FM audio signal and the HD FM audio signal based on the determined correlation. The signal processor may include a multiband limiter configured to generate a multiband limited audio signal responsive to the input audio signal, an HD FM audio processor configured to generate the HD FM audio signal responsive to the multiband limited audio signal, and an analog FM audio processor configured to generate the analog FM audio signal responsive to the multiband limited audio signal and to delay the analog FM audio signal responsive to the timing control signal.

A stereo-phonic frequency modulation receiver includes: a frequency modulation demodulation circuit, receiving a reception signal, and generating a demodulated signal according to the reception signal; a frequency-division demultiplexer, generating a sum signal, a difference signal and a pilot amplitude signal according to the demodulated signal; a dual sound channel separation circuit, generating a left-channel output signal and a right-channel output signal according to the sum signal and a weakened difference signal; and a weakening circuit, weakening the difference signal according to the pilot amplitude signal or a signal-to-noise ratio (SNR) to generate the weakened difference signal.

A stereo-phonic frequency modulation receiver includes: a frequency modulation demodulation circuit, receiving a reception signal, and generating a demodulated signal according to the reception signal; a frequency-division demultiplexer, generating a sum signal, a difference signal and a pilot amplitude signal according to the demodulated signal; a dual sound channel separation circuit, generating a left-channel output signal and a right-channel output signal according to the sum signal and a weakened difference signal; and a weakening circuit, weakening the difference signal according to the pilot amplitude signal or a signal-to-noise ratio (SNR) to generate the weakened difference signal.

A method for processing an FM stereo signal. The FM stereo signal is digitized and divided into overlapping blocks, which are transformed into the frequency domain. Individual spectral lines of the difference signal are lowered if these have a higher magnitude than the respective spectral lines of the sum signal. The sum and difference signals are then transformed back.