10.10.2006 08:00 AM
Originally featured on BroadcastEngineering.com
Vermont broadcasters near completion of combined HD transmission facilities
If all goes as planned, WCAX-TV (CBS), WPTZ-TV (NBC), WVNY-TV (ABC) and WFFF-TV (FOX) will soon join Vermont Public Television on air in HD from a combined transmission facility on Mount Mansfield in north-central Vermont.
The culmination of a decade-long process, the combined on-air HD presence will bring to a close a joint effort that has required careful planning, tricky regulatory approval and an accelerated building schedule to accommodate the four-and-a-half months each year that weather permitted construction. Vermont Public Radio and Clear Channel will join the combined transmission facility as well.
Home to WCAX’s transmitter site since 1954, Mount Mansfield rises 4393ft above sea level in the Green Mountains. While the mountain’s elevation and location made it the logical spot for the combined facility, its fragile ecosystem and scenic beauty made the site’s location challenging for the Mount Mansfield Colocation Association - the umbrella group representing the stations that are part of the transmission combine as well as the state and property owners.
For instance, endangered plants - not seen elsewhere outside the Arctic Circle - required construction crews take special care to maintain the environment. Tower height was another concern. The three new transmission towers at the complex could not exceed 200ft. To do so would require flashing red tower lights, something unacceptable to regulators and neighbors alike, according to WCAX vice president for engineering Ted Teffner.
Teffner, who led the project, said the actual work on the site began two years ago. Since then, a new transmission building for the combined digital TV facilities and radio partners has been built near the existing facility belonging to Vermont Public Television. The three towers used for the combined site include a 130ft tower with a 52ft Dielectric antenna shared by WPTZ and WCAX that produces a cardioid coverage pattern for WPTZ and an omnidirectional pattern for WCAX thanks to some engineering ingenuity on the part of Dielectric, he said. The top 40ft of the tower is occupied by a Shively four-bay FM panel antenna, which WEZF and Vermont Public Radio will share in 2009 after the analog TV switchoff.
Next to the 130ft tower is a 98ft tower occupied by the WFFF antenna and WVNY’s antenna. About 180ft to the east is the 80ft Vermont Public Television tower. When it comes to transmitters, Vermont Public Television, WCAX and WPTZ went with Harris and WVNY and WFFF rely on Rohde & Schwarz, Teffner said.