New Tools for New Audio Systems

Test and measurement for embedded audio creates its own set of problems
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PADUCAH, KY.
For decades, troubleshooting audio and video at a broadcast facility was pretty straightforward: just keep “patching back” until the problem was cleared, then re-route the signal, bypassing the offending component.

It was simple.

With analog audio, even a simple set of high impedance headphones could often locate a problem without patching at all. Alas, with the widespread acceptance of AES audio during the past decade, most high-Z headphones have been doomed to the storage cabinet. Also with broadcasters now embracing embedded audio, in many cases the audio patchbays are sharing a space along with the headphones in that same storage cabinet.

The “patching back” logic is still a good practice when using embedded audio. However, with this type of audio, it may not be that simple.

With embedded audio sharing the same path as video, breaking paths with patches to solve an audio problem can introduce video problems, and vice versa, as many components in today’s modern facility are “multifeatured.” There are embedders, de-embedders, upconverters, crossconverters, downconverters, logo inserters, closed captioning inserters/deleters and more. Upsetting that delicate balance can cause some immediate problems immediately, or set a future trap for you.

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Ensemble Designs' new BrightEye 33 is a 1x8 d.a. that can be used in a stereo configuration as a 4 output d.a. A SIMPLE FIX MAY RICOCHET

As an example, when the wrong audio is in the correct audio path, it can be very tempting to just de-embed the audio up-stream and patch it in down-stream. While this may appear to solve the immediate problem, it can cause routing problems, lip-sync problems and more. Often, modules in mid-stream provide down-mixed audio for talent monitors and house routing. This type of “patch around” solution could kill audio, captioning and video from those paths.

With the design of modern broadcast facilities, embedded audio plays a large role in eliminating lip-sync and other routing errors; however, engineers and operators must have the proper information and tools to troubleshoot audio issues. Of equal importance is a facility design that embraces embedded audio.

Before there can be a response to an issue, that issue has to be recognized. Most audio monitoring is still accomplished with analog monitor outputs. According to Cindy Zuelsdorf, marketing czar for Ensemble Design in Grass Valley, Calif., the company’s customers have been asking for additional analog audio monitoring ports on both of the company’s BrightEye and Avenue product lines. The addition of 5.1 surround monitoring to a TV plant has further complicated matters, with some resorting to a stereo down-mix. Zuelsdorf says that her company is addressing broadcasters’ multichannel audio issues too.

“We’ve just introduced a new analog audio d.a. with 8 outputs at IBC 2009 to accommodate their multichannel monitoring needs as well,” she said.

Systems integrators are also addressing these enhanced monitoring requirements.

“Most integrators and designers are now dedicating a router destination for the sole purpose of audio/video monitoring at key operator positions,” said Martin Dyster, audio application manager for U.K.-based Television Systems Limited (TSL). “As an integrator and manufacturer, we get a lot of customer feedback throughout the process, and most customers want each component to have Ethernet connectivity for troubleshooting purposes.”

This approach is also reflected in other products reaching the marketplace.

“We’re changing the way operators monitor audio for level issues,” said Hal Buttermore, field application engineer for Linear Acoustic in Lancaster, Pa. “With our AERO.QC products, the display screens have an ITU bar graph which is color coded for ITU loudness monitoring, with violations easily noticeable.”

On a slightly different front, the trend towards flat screen video monitoring in control rooms is beginning to affect the design of some audio monitoring equipment. “With monitor walls becoming less deep due to products such as multiviewers, short depth audio monitoring products such as our Compact Monitor series are becoming very popular with integrators,” said Paul Keller, product manager of test and measurement for Harris’ Videotek equipment line.

Once a problem is recognized, one must troubleshoot the embedded audio issue. One of the most straightforward pocket tools appears to be the Harris Videotek HD-Star.

This handheld unit is a test generator and HD-SD monitoring device, and includes embedded audio capabilities. “During the two years it has been on the market, the HD-Star has been more popular that we ever expected,” Keller said.

Products such as this might prove handy in the cramped space behind equipment racks.

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Linear Acoustic AERO.QC THE IMPORTANCE OF AUDIO FACILITY DESIGN

While manufacturers and integrators have a handle on the overall picture, there is no substitute for being in the trenches. Dan Carpenter, regional engineering manager for the Sinclair Broadcast Group, said he has seen it all with regard to embedded audio, including downstream keyers re-arranging the audio, incorrect sample rates in the audio and numerous incompatibility issues with digital/embedded audio. Carpenter added that his group has 24 stations constructed for HD embedded audio master control operations.

“All of our sites have proper monitoring and evaluation tools at key router destinations,” Carpenter said. “We use a variety of monitoring and test gear, including some prosumer handheld devices to monitor 5.1 behind the racks.”

Carpenter observed that this is not the way it is with some DTV buildouts, though.

“Due to budget constraints, many stations have gotten away from planning their facilities with sufficient distribution amplifiers and patch points,” he said. “With embedded audio, facility plans must include proper monitoring and patching points along the entire path, not just upstream.”

Carpenter noted that Sinclair paid particular attention to source types when designing audio facilities.

“We embed our audio-only sources on HD black to keep all routing in the same level,” Carpenter said. “That is how serious we are about embedded audio.”

It’s clear that multichannel embedded audio requires not only specialized equipment; system planning must also be thorough and accurate.

I can remember quite some time ago when our station added stereo audio. Our then-CE quipped that this would never work at a TV news station. I suppose that he would carry such an attitude into this era as well. However I’m afraid that he wouldn’t be very successful these days. We must all embrace and advance with new technologies. If we don’t, we’re destined to wind up like the dinosaurs.

Joey Gill is Chief Engineer for WPSD in Paducah, Ky.