RF Facilities Excellence Awards Winner
NBC-affiliate WBBH-TV, owned by Waterman Broadcasting Corp., had an NTSC tower that was 20 years old and didn't meet federal or local standards for wind loading. It wasn't economically feasible for the station to upgrade it. With an FCC digital deadline for channels 15 (WBBH-TV) and 41 (WZVN-TV), station management decided to construct a new tower and a new building for its digital transmitters.
The design for the Punta Gorda, FL, tower was based on ANSI EIA/TIA-222-F code. Contractors Kline Towers and Carolina Towers were chosen for their quality and experience in constructing tall towers. Contractor Owen Ames Kimball was hired to build a 2000-square-foot facility to house the station's transmitters and extensive RF transmission system.
One time-consuming task was convincing Charlotte County that a new tower was needed, but once it was approved, Waterman agreed to build the “replacement” tower and dismantle its existing tower by the NTSC cessation date.
For loading and RF loss considerations, coaxial and waveguide runs on the new tower were limited. Two platforms were specified, one at 450 feet and another at 1350 feet, each supporting equipment enclosures. Thirty-six-count, single-mode fiber, as well as a fifty-pair Telco cable, was run from the transmitter facility to the 450-foot platform, where it was broken out to patch panels, then carried to the 1350-foot platform where it terminated. Nucomm's V-Stream digital 7GHz STL radios were specified to be a fully redundant split system with hot-standby and antenna diversity switching between two six-foot Andrew antennas. Dual receivers were placed at 450 feet, and their 70MHz output was sent down the tower via fiber optic transmitters. The 70MHz demodulator then output the 310M to feed each of the ATSC transmitters' dual exciters. The analog 2GHz Nucomm FR6 digital-ready receiver was placed at the 1350-foot level, along with an NSI Superquad antenna system. This system was split also and the 70MHz signal delivered to the building in the same manner as the STLs. Along with eliminating a 1450-foot coax run, a significant signal level increase was realized at the ENG demodulator. The TSL was then output to the main STL antenna using the fiber in reverse fashion.
According to Dan Billings, Waterman Broadcasting's director of engineering, the system's most interesting feature involves transmitting the digital signals for the two stations from one location through one transmission line and antenna. The Andrew-designed RF system switches and combines signals from the WBBH and WZVN transmitters. The combined 54KW signal is carried through 7-3/16-inch MACXLine to the broadband panel antenna that produces 1MW ERP per channel. Combining both transmitters on one antenna is a practical solution for a complex application, with cost savings on line, antenna, tower and construction expenses. This also enables an optimum directional coverage pattern.
Dan Billings, Waterman Broadcasting
Mathew Gaige, Waterman Broadcasting
Bennie Barnes, Waterman Broadcasting
Jean Lecordier, Kline Towers
Dawn Kazlauskas, Andrew
Bill Yorns, Thales
Bryan Cogswell, Thales
Rick Gutknecht, Owen Ames Kimball
Larry Kitchens, Carolina Towers
Andrew RF system, transmission line and antennas
Nucomm microwave radios
NSI ENG antenna and control system
Cummins/Onan generator/transfer switch
APC UPS system