Analog and digital audio alignment in the hd radio exciter engine (exgine)

A method for controlling operation of a hybrid radio exciter engine, the method comprising:

• receiving digital audio packets of main program service (MPS) audio at a digital port of the hybrid radio exciter engine and providing the digital audio packets to a modem of the hybrid radio exciter engine;
• receiving an audio engineer society format (AES) audio signal of the MPS audio at an analog port of the hybrid radio exciter engine, wherein the AES audio signal is a digitized version of an analog audio signal of the MPS audio;
• aligning the AES audio signal in time with corresponding digital audio packets at the modem;
• and
• generating a frequency modulated (FM) hybrid radio signal for broadcast that includes time-aligned analog MPS audio and digital MPS audio.

An apparatus for generating a frequency modulation (FM) hybrid radio signal for broadcast, the apparatus comprising:

• a digital input port configured to receive digital audio packets of main program service (MPS) audio;
• a modem operatively coupled to the digital input 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 FM hybrid radio signal;
• a sampling circuit configured to resample the AES audio signal to produce a clock-restored AES audio signal;
• and
• a rate adjustment circuit configured to determine a sampling rate of digital audio information included in the digital audio packets and adjust a rate of resampling of the AES audio signal to reduce a sample rate difference between an audio sample of the clock-restored AES audio signal and a digital audio packet corresponding to the audio sample;
• wherein the modem is configured to generate the FM hybrid radio signal using time-aligned AES audio samples and digital MPS audio.