New Service Modes for HD Radio™ Transmission

An HD Radio broadcast signal is uniquely defined by its service mode. Several service modes have been available to AM and FM broadcasters for nearly two decades. Only recently have various HD Radio stakeholders begun requesting additional backward-compatible options for improved robustness and capacity. Even non-backward-compatible improvements could be introduced for all-digital, international, and new North American data applications. This paper proposes a new set of service modes developed in response to these emerging market demands and opportunities. To enhance flexibility, each new service mode may employ one of three quadrature amplitude modulation formats, allowing broadcasters to trade robustness for capacity. Since all new service modes feature frequency diversity between lower and upper sidebands, as well as time diversity between main and backup components, they are collectively referred to as lower-upper-main-backup (LUMB) service modes. This multidimensional diversity scheme offers fast tuning and enhances signal robustness in the presence of selective fading, interference, blockages, and other channel outages.