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 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.

In a group level control section, a largest output level among those in channels belonging to a relevant group is selected automatically as a group level. By operating a control part of a channel level control section displayed on a basic screen, an output level of an input channel corresponding to the operated channel level control section can be controlled. Further, by operating a control part of a group level control section, output levels of the input channels belonging to the group can be collectively controlled with difference in levels among the input channels being maintained.

An ultrasonic emitter system includes a digital processing system for adjusting the amplitude of an ultrasonic carrier signal to increase audio levels of an audio signal during lower power portions of the audio signal. To increase the audio levels without introducing unwanted audio and/or distortion, an additive constant is added to the ultrasonic carrier signal based on a rolling average audio signal power measurement.