Audio Processing for HD Radio
4.1 What an audio codec is and how it works
In the previous chapters, we have stated that the digital audio on an HD Radio signal is data-reduced audio. Due to the constraints of the assigned channels on AM and FM stations, a non-data-reduced signal would be far too large to transmit. An audio codec is therefore used to remedy this situation.
An audio codec has two parts: an enCOder on the transmit side, and a DECoder on the receive side. These work in tandem to pass the audio from the transmitter through the RF channel and into the listener’s receiver.
Unfortunately, I cannot give details about how the HDC codec used in the iBiquity Digital HD Radio system actually works. This information is proprietary ...