RAYMOND, Maine—Dielectric announced that it has completed a repack project for DTV Utah’s community TV transmission facility, for which it installed an ATSC 3.0-ready multi-channel combiner and waveguide switching system.
The DTV Utah facility houses transmission systems for nine Salt Lake City-area stations. Eight of the stations, six of which were repacked to new channel assignments, broadcast from specialized multi-channel antennas. James and James Consulting managed the project, including the design, integration and commissioning of the Dielectric system.
Requirements for the project called for a system that could transmit from 9,050 feet above sea level and across the Wasatch Front terrain north and south of Salt Lake City with specialized antennas built in 1999. DTV Utah was not able to retune the RF system for all of the repacked channels, which called for replacing the combiner system. In addition, there were mask requirements for three adjacent channels.
Because the previous combiner and mask filters could not be removed from their location, Dielectric designed what it calls its most compact combiner to date, a 14x16-foot system to fit into the available 17x20-foot space while leaving room for a tenth transmitter.
Some of the reported technical challenges had to deal with the three adjacent channels and their need for sharply tuned filters to allow for the full use of each channel’s bandwidth. While the group delay measurement is increased slightly from a more broadly tuned filter, the facility’s new GatesAir and Rohde & Schwarz transmitters provide corrections to make the group delay at the channel edge negligible.
Dielectric’s other contribution to the DTV Utah facility was the waveguide switching on the combiner’s input. This allowed for various combinations of main and backup antennas.