Digital television (DTV) is getting closer, bringing with it a major headache for audio engineers working with wireless microphone and personal monitoring systems. Already faced with existing analog television signals occupying useable bandwidth, as well as interference from local emergency services and transit companies, not to mention venue security and management communications systems, touring live sound engineers must now also cope with a burgeoning list of DTV facilities.
Over 10 years in the making, DTV has been mandated by the Federal Communications Commission (FCC) as the sole over-the-air broadcast television transmission medium-eventually. But in the meantime, as the nearly 1600 local broadcast television stations in the U.S. make the transition to fully digital operation, they will simultaneously operate both analog and digital feeds, further clogging the already crowded airwaves.
To help RF specialists through the UHF maze, Sennheiser has launched a new website that offers tools and resources for finding available frequency bandwidth anywhere in the United States. Go to www.sennheiserusa.com and select "RF Frequency Finder" from the "Quick Links" listing.
The site includes recommended tunings for Sennheiser Evolution Wireless and 3000 and 5000 RF Series systems for situations that require the re-tuning of factory presets or where multi-channel requirements exceed the system's factory presets. A three-step guide allows audio engineers to download Sennheiser wireless equipment stock frequency and available custom grouping guides, cross-referenced to television channel orientation, for study during tour pre-production or while on the road. A 50-state grid provides links to Adobe PDF downloads with comprehensive listings of the current analog and DTV frequencies in use in the major cities, including bandwidth allocations for future DTV transmission.
RF engineers may use the guides to select the wireless frequency range with the least number of TV signals and choose the Sennheiser wireless frequencies applicable to their particular RF system that fall within the unused TV channels for their tuning requirements. DTV facilities are coming online regularly, and broadcasters may petition the FCC for their DTV frequency assignments to be reallocated, so the website also includes a link to the FCC, where DTV spectrum allocation is continually updated.
Evolution Wireless, which supports up to 1,280 frequencies, also has tremendous tuning capabilities. The website's tuning menu allows engineers to retune Evolution Wireless factory presets to frequencies that are not affected by local or regional TV broadcast signals. The 3000 and 5000 RF Series products offer a sliding 24 MHz micro range feature, unique to Sennheiser products, that may be factory-adjusted throughout the RF spectrum to accommodate specific requirements.