Doug Lung / 09.19.2008 12:00AM
Harris Introduces New UHF Transmitters Built With New Freescale LDMOS Devices
RF Report recently discussed the agreement between Freescale Semiconductors and Harris to develop more efficient solid-state transmitters. Harris Corp. showed the result of this collaboration at IBC with its Maxiva line of TV transmitters. The Maxiva line includes low power UHF air-cooled solid-state transmitters and high power UHF liquid-cooled solid-state transmitters.
The air-cooled UAX series transmitters operate at power levels from 10 to 2,000 watts and come with the Harris Apex exciter, which is capable of ATSC, DVB-T, DVB-H, DVB-T2 and other digital standards. The transmitter can also transmit analog signals. It uses the new 50 V LDMOS device from Freescale Semiconductor, which allows higher power density in the UAX transmitters.
"Broadcasters globally are faced with the unique challenge of providing clear, high-quality over-the-air transmissions to a specific area or region, often with a limited budget," said Tim Thorsteinson, president of Harris Broadcast Communications. "As more broadcasters transition to digital, the need for multimedia-capable yet cost-efficient low-power transmission platforms becomes greater. The new Harris solid-state architecture is ideal for broadcasters that require a compact, affordable, low-power solution that retains the reliability and robustness needed to reach every consumer."
The Maxiva ULX series transmitters provide power levels starting at 1 kW and, according to Harris, go up to "the highest power levels required for terrestrial digital transmission."
Based on DTV tube-based transmitter installations I've seen, this would mean they have the ability to generate DTV output powers greater than 55 kW average. These transmitters use the Apex M2X exciter. The exciter is able to generate analog signals or, through software updates, DTV signals for multiple standards. Each Maxiva ULX cabinet can provide power up to 8.7 kW for DVB-T and COFDM or 26.2 kW analog peak power. Since ATSC has a lower peak to average ratio than DVB-T, I'd expect output powers up to 10 kW per cabinet for ATSC. This would mean six cabinets could be combined to match (and possibly exceed, depending on combiner losses) the power of a two-tube MDSC IOT transmitter.
"A large number of terrestrial broadcasters globally are operating at high power levels for UHF broadcasting, which can be very expensive due to the amount of radiated power required to cover a large area or region," Thorsteinson said. "Many of these broadcasters are seeking a high-power transmitter that offers a true value proposition for transmission at high power in the UHF spectrum. The new Harris solid-state architecture provides exceptional value by minimizing operational costs over the course of its life without sacrificing the reliability and robustness that broadcasters expect from a transmitter."