The audio qualities of the digital and analog signals are characterized and compared for the HD Radio In-Band On-Channel (IBOC) Hybrid FM broadcast system. The Hybrid HD Radio modes of transmission carry the original (host) analog signals simultaneously with a digital signal conveying the same audio program, but with superior sound quality. The digital signal is transmitted at a lower level than the analog signal in a carefully designed modulation scheme that minimizes corruption and maximizes compatibility with the host analog audio. Audio quality characteristics, such as SNR for an analog signal, are compared to audio characteristics for a digital audio codec.
