Fourth Annual Excellence Awards
RF Systems –nominee

The first step was to fit the new DTV system in an existing analog transmitter building housing dual 30kW Ch6 transmitters. This seemed impossible because no easily accessible excess space was available. However, the team created the needed space by reducing the size of several storage rooms and office areas.

The station installed a WAN connecting the studio, transmitter site and other sites with wireless 5.8GHz IP radios moving data at 18Mb/s. Using the IP-compatible board in the transmitter and software allows KVIE to access the DTV transmission system anywhere there is an Internet connection. Thales engineers can also access the system remotely via a secure VPN for setup, control or troubleshooting.

Another challenge was the lack of space for the high-voltage power supply (HVPS) and cooling condenser system. Refrigeration air conditioning cools the building for the analog transmitter. The A/C compressors were relocated to the roof to make room for the HVPS. Because the transmission building sits on 13ft high stilts to keep the facility above the San Joaquin Delta flood plain, the team attached additional steel reinforcement beams to the floor to handle the weight of the HVPS. The DTV transmitter cooling condensers were mounted on a frame suspended above the roof to allow for roof maintenance, and shock-mounted to minimize vibration to the building. The mask filter was wedged into the ceiling of the building, leaving a scarce 2in clearance between one outside wall and 2in clearance on the opposite side of the filter and air conditioning ductwork.

To meet its second goal — equipment that would work for all UHF channels — the station used 5in heliax for the transmission line. In addition to economic benefits, this approach was much quicker and more efficient — installation on the 2000ft tower took only a week. The match into this transmission line/antenna load is superior to the match into the station dummy load.

Because KVIE-TV uses a VHF low-band channel, the building has only a 120/208 VAC service. The new transmitter required a 480 VAC service. Installing a new 480 VAC service into the building was an extremely costly and time-intensive proposition. Thankfully, the existing service had excess capacity, including a backup generator. Power needs were supplied by a 208-to-480 VAC step-up transformer with sufficient capacity for two MSDC UHF IOT transmitters. Thales’ Paragon requires a smaller 480 VAC service than typical IOT transmitter systems.