The coming of HD Radio to WKSU


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The coming of HD Radio to WKSU began in 1991 on a tour bus in Las Vegas.
Facility Showcase, Jan 2010

It was a balmy April afternoon in Las Vegas when I boarded the bus in 1991 for a tour through the city. No, it was not a sightseeing trip but rather a drive around town to listen to a DAB FM test station. Each seat on the bus had a set of headphones and an A-B switch. Switch position A provided the analog audio side of the broadcast and position B presented the latest and greatest in digital FM broadcast technology — clean, noise-free, high-fidelity program audio. The difference between the low-power test transmitter's analog broadcast and its DAB signal was highly impressive — especially when the analog signal went into noise and the stereo image collapsed. It was on that balmy Las Vegas afternoon that I first caught the vision for just how much FM broadcast audio might be improved. I have never lost focus of that vision.

We now fast forward through many years of hopes, dreams, and promises made by DAB and IBOC technology developers to the present day adoption of in-band on-channel (IBOC) AM and FM broadcast technology as the U.S. standard. Like so many stations across the country over time, WKSU's management team has maintained a close watch on the development of IBOC technology, its potential benefits, costs, and perhaps turning out to be the most important, the timing of its availability in relation to other competing listening technologies including satellite and Internet radio.

Going digital

Repeater station WKRW has the 1992 installed analog Harris transmitter and the new IBOC transmission equipment behind.

Repeater station WKRW has the 1992 installed analog Harris transmitter and the new IBOC transmission equipment behind.

In 2003, WKSU chose to construct its fourth FM repeater station, a 4kW facility located in north central Ohio. Via grant funding provided from federal and state government agencies, a decision was made to have this repeater station, WNRK, become the first IBOC broadcast facility within the WKSU network of stations. The station went on the air in 2004 using a Harris Z hybrid transmitter to provide an analog and IBOC HD-1 signal. Audio delivery to the site at that time was by a high-quality FM tuner receiving the WKSU analog signal for rebroadcast.

WKSU management continued monitoring IBOC technology progress, implementation across the country, receiver availability and market penetration. Questions about its benefits to the station's public radio operation began to rise — especially regarding the potential costs required to bring the entire network of stations (five full power and two translators) up to IBOC capable standards.

In 2005, with assistance from a grant received from the Corporation for Public Broadcasting (CPB), the opportunity came to add an IBOC signal to WKSU. That led to more questions as to what method of IBOC transmission technology to use. Our broadcast engineering team settled on a Harris Split-level system that required the addition of a Harris Z transmitter, a Dielectric RF combiner, a reject load, and all of the related RF plumbing. Fortunately, the WKSU transmitter building was large enough to accommodate the additional equipment including sufficient electrical and ventilation systems. The Split-level system was successfully added to WKSU's Broadcast Electronics FM-20T analog transmission system. At that time, program audio delivery to the site from WKSU's Broadcast Center located 13 miles away on the main campus of Kent State University in Kent, OH, was via a Harris CD microwave link with an Intraplex T-1 delivery system backup. Both systems were limited to 15kHz high frequency response so WKSU's HD-1 signal was on the air but not yet with a full 20kHz audio signal for use on the IBOC signal.

Broadcast Electronics FMi-1405 IBOC transmitter and associated equipment at repeater station WKSV

Broadcast Electronics FMi-1405 IBOC transmitter and associated equipment at repeater station WKSV

As the journey continues through time, the fast-forward button takes us to the year 2008. WKSU had a major decision to make. Either add 5,000 square feet onto the Broadcast Center building or complete the installation of IBOC technology at its non-IBOC stations and further enhance the network with the implementation of multicast channel and program associated data (PAD) capabilities for each station. As station management faced the launch of a capital campaign, a professional firm was retained to conduct a feasibility study with potential significant donors for purposes of determining which project they would be more likely to endorse. Surprisingly, the wants, needs and demands for more “channels” — both via broadcast and Internet — won out. The quiet phase of a digital conversion capital campaign was launched and a commitment to have a complete IBOC/multicast, PAD-capable network was made.

The WKSU network of stations, Ohio's largest combined FM radio signal, collectively reaches a widely diverse audience throughout all or part of 22 counties in northeast and north central Ohio. Nearly four-million persons reside in the region that ranges from densely populated urban areas to rural, agriculturally oriented communities. The need to provide programming of significant value to a diverse audience led to a design goal of being able to program the analog and all digital channels of each of the five full-power stations (main and four repeater stations) independently with origination occurring at the Broadcast Center. With the help of generous capital campaign contributors and multiple grants received from the Corporation for Public Broadcasting, the WKSU total IBOC commitment was launched and the multi-channel centralcasting concept design undertaken.

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