New 10-channel UHF combiner brings wider range of DTV service down under

A new, advanced UHF combining system is bringing access to a wider range of digital DTV service to television viewers in central Victoria, Australia.

The RFS combining system installed at Lookout Hill in Australia is designed to accommodate 10 digital and analog UHF TV channels.

Installed at Lookout Hill about 68 miles northwest of Melbourne, the combiner accommodates 10 UHF channels and is believed to be the biggest of its kind in the world.

Broadcast Australia owns the transmission site. It provides transmission facilities for two government-owned broadcasters (ABC and SBS) and three regional broadcasters (WIN, PRIME and Southern Cross).

Site preparations for the new UHF DTV service have been ongoing for the past two years. The new service will facilitate the transfer of existing regional VHF television service to the UHF band, which will prevent interference wit metropolitan VHF DTV channels.

As part of the site makeover, key broadcast infrastructure has been replaced, including antenna, switch-frame, feeder systems and the UHF combiner.

Radio Frequency Systems (RFS), a global provider of RF technology, systems and services, designed and provided the 10-channel UHF combiner. According to company project manager Mick Bennet, “The challenge was to come up with a combiner that could handle seven adjacent channels, and 10 overall, given the huge amount of power running through the system.

“To my knowledge, there isn’t another system in the world that can accurately combine this number of channels at this level of power,” he said.

The RFS combiner is a balanced, directional waveguide filter/combiner chain designed to accommodate 10 signals from five 30-kilowatt (kW) analog transmitters and five 7.5- to 10-kW digital transmitters. The combiner effectively acts as a ‘DTV cleanup’ mask, and uses a network of cross-coupling paths and a six-pole elliptic function filter response to ensure an efficient and compact in-line design.

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