By Steve Harvey
Macomb, IL (May 20, 2005)--Corporation for Public Broadcasting funding support for a second wave of HD Radio is allowing public radio stations to convert to digital audio now while preparing for secondary audio with datacasting in the future. The mandated iBiquity Digital HD Radio scheme delivers those digital services--which can include additional channels and data--as sideband transmissions simultaneously with the existing analog signal.
Western Illinois University public radio station WIUM-FM of Macomb, IL, together with sister WIUW-FM in nearby Warsaw, offers just one example of the path to HD Radio. In the case of this facility, the final transmission upgrade came in the form of a Broadcast Electronics Total Radio package, which was installed following a major overhaul of the transmitter sites and included BE's HD Radio transmitters, exciters and signal generators as well as a Big Pipe wideband STL.
"We have future plans to be able to offer localized programming on WIUW requiring an STL feed," explained WIUM's assistant director for technology, Greg Manfroi. "We are also interested in running a secondary audio channel via the NPR Tomorrow Radio Project."
That means exporting a total of three 44.1 kHz (the HD Radio standard) stereo audio channels--four if he adds a separate secondary audio channel on WIUW--plus a 6 kHz audio channel for the reading service, while leaving bandwidth for Program Associated Data (PAD), said Manfroi. "We didn't want to use T-1 lines due to the recurring monthly costs. But the Broadcast Electronics Big Pipe system can provide all of this."
But the final transmission upgrade came only after the transition from analog to digital workflow some 2 1/2 years ago, he points out. "I replaced analog air and production consoles with a Logitek router. Air and production studios utilize control surfaces that control this router."
He noted, "I was forced to use equipment from a decision that pre-dated my arrival and use an analog console in a music production studio. Live performances are mixed in this studio on another analog console. I plan on replacing the live console with a Mackie Onyx and use FireWire to feed a DAW. This will also allow enough recording channels to produce 5.1 surround."
As Manfroi observed, "The analog console does offer a benefit as it is an emergency last-resort console to put on air in the event of a catastrophic router failure."
During the transition, recording moved from digital tape to 44.1 kHz disc in preparation for HD. "All on-air recorded audio is on hard drive using Broadcast Electronics AudioVaultExpress system," he shared. "The automation uses AudioVaultExpress doing all fades and ducking using the Digigram sound card in the Vault PC."
He continued, "I use Marshall [MXL] condenser mics as they offer extremely low cost for the sound they produce. They are digitized in the studio with Graham-Patton mic preamps. All mic pres and CD and MiniDisc players are fed from their respective digital outputs to the router. The MiniDisc players are legacy items, and I discourage their use over linear recording mediums. A-to-D conversions are kept to an absolute minimum."
With news playing an important part in the broadcast schedule, continued Manfroi, "We've purchased two Marantz Flashcard recorders for the news reporters so we can produce newscasts from linear audio. We also use Broadcast Electronics NewsBoss newsroom software, and it's integrated with AudioVault to allow reporters and the news director to edit, audition and import/export audio at their desks without going into the studio."
To further streamline the process, "I will be setting up an 802.11b access point and the reporters will get 802.11b laptops. Initially this will be used to let the reporters mix a story in the field and dump it into the system without plugging a wire into anything."
To ensure minimal data loss, Manfroi said, "I set up RAID controllers on all PCs so the files have some measure of automatic backup protection. The AudioVault system also copies the files to each Vault machine, actually giving us six copies of everything."
Before going to air, separate processing for the analog and HD signals is provided by a new Orban 8400 processor with HD option. "This replaced an Orban 8200 processor," reported Manfroi, "which will probably be utilized for the HD secondary audio channel initially."
All that's left on his shopping list--for the moment, anyway--are router system control surfaces, an off-air analog/HD repeater receiver, a low-cost audio processor for the secondary HD channel and HD Radio monitoring equipment. "I would like to know my HD is OK."
By Steve Harvey