The Oklahoma Educational Television Authority (OETA) provides public television programming throughout Oklahoma. While OETA operated on VHF frequencies for analog, the FCC initially allocated UHF frequencies for digital simulcast. OETA built UHF DTV facilities to fulfill this requirement but felt that it would be most beneficial to return to VHF for DTV operation following the analog sunset. This would save the noncommercial network thousands of dollars in energy costs each month.
The first step was to issue a request for bids for two VHF transmitter systems, one of which would serve the Tulsa market and the other for Oklahoma City. To ensure a solid, reliable DTV signal, OETA specified dual transmitter systems for both locations, complete with switching capability, that would detect any failure and automatically switch to the backup transmitter. This system was also specified to allow both transmitters to be combined to air, a feature that would turn out to be very useful in the future.
OETA selected Axcera to build the system. Axcera offered a clean design that met all of the specific needs for the unique dual transmitter configuration. Each system uses two Axcera Innovator HX transmitters and a Myat switchless combiner, allowing the main, backup or both transmitters to be selected while the system is on the air. Additionally, Axcera’s long history in the industry and reputation for quality and service gave OETA a high level of confidence.
OETA set a goal to convert to 100 percent digital by the original 2009 analog sunset date of Feb. 17, 2009. Because the broadcaster chose to return to its analog frequencies, each system needed to be installed while both the existing VHF analog and UHF digital signals remained on the air, and the systems needed to be ready to flash-cut on Feb. 17. This required preparing the existing transmitter facility in Tulsa and building a new transmitter facility in Oklahoma City.
Because the majority of the Oklahoma City facility construction occurred in December 2008 through January 2009, it was not without incident. This included an unfortunate situation in which a worker pumping concrete slipped, and the hose he was holding pumped concrete onto the new air-conditioning unit, rendering it useless. However, with hard work and some long hours, the facility was completed less than one week prior to Axcera’s arrival to install
The systems were brought online in time for a successful Feb. 17 cutover. The equipment all worked well. However, OETA soon discovered that the FCC allocation of 15kW ERP was not enough VHF power to replicate the original analog coverage area. This is where the good fortune of the unique N+1 system came into play. Because the N+1 system would allow both the main and backup transmitters to be combined to air, output power could be doubled, providing strong coverage throughout the service areas in both locations.
The system is operating reliably and meeting all of OETA’s goals. Between savings from reduced electricity costs and elimination of lease payments in Oklahoma City, OETA is realizing a savings of approximately $30,000 per month, while providing an excellent signal to its viewers.
New studio or RF technology — station
Submitted by Axcera
OETA: Earle Connors, dir. of eng.; Ted Newcomb, sr. tech.; Mark Norman, deputy dir. of tech.
Axcera: Jeff Heldman, app. eng.; Walt Beaver, sr. field svc. eng.; Don Thomas, sr. field svc. engineer; Jim Moore, sr. field svc. eng.
Myat: Derek Small, dir. of filter prod.; Stephen Kolvek, dir. of coaxial prod.
Technology at work
Axcera: HHV3750AD VHF DTV main/alternate transmitters, HX series main/alternate controller
Burk: GSC3000 remote control
Myat: DTV mask filters, switchless combiners
Panasonic: BT-LH1700W monitor
Sencore: MRD-3187A demodulator
Spectracom: 8195B GPS receiver