FM single frequency networks (SFNs) are recognized by the FCC as fill-in booster stations and are in common use for FM operation today. With fewer frequencies available for FM translators, building out on-channel coverage is often the best option and enhances a station’s frequency branding. Today, many broadcasters are desiring to extend both their FM and HD Radio coverage.
The planning parameters required for a hybrid FM+IBOC booster installation that minimizes on-channel interference are detailed. Tight time synchronization is required between all nodes of the SFN for both FM and IBOC. We detail a method to achieve precise input to output time synchronization for In-Band-On-Channel (IBOC) signal transmission across multiple HD Radio transmitters. Lab results of the signal operating synchronously demonstrate seamless handoff from one transmitter to the next.
A real-world installation at KUSC, Los Angeles CA, is shown including the equipment used, drive test results and overall system performance.