NMT Launches HDTV Trucks

[Gregg Lengling]

By Steve Harvey

Aug 11, 2003, 16:20 PST




National Mobile Television (NMT) has launched the latest in a line of high-definition television production trucks. HD4 is the most ambitious HDTV unit to be produced by the company so far, offering not only fully digital HD video but also an exclusively digital audio path. "From an audio standpoint it is unique," explains NMT president Jerry Gepner. "It is the only television production truck in this country, to my knowledge, that is designed to use entirely AES signal routing and processing."

Digital consoles have become the norm in large-scale television production vehicles, notes Gepner, whose company was on the leading edge of the trend. "We've been using digital desks longer than anyone," he recalls. "We had the original SSL Aysis Airs in HD1 and HD3, so we have more experience as a company dealing with digital consoles."

Space is at a premium in mobile production trailers, making a dual-fader path console a necessity. To handle the requirements of HD4, NMT chose to install a Solid State Logic MTP digital production console, the third MTP for the company and its fifth SSL desk. The 96-channel MTP in HD4 supports 120 digital inputs, 104 analog inputs and 60 microphone inputs.

Not that this is a small truck-far from it. "It's 53 feet long, which is the legal limit in this country," reports Gepner, "and 13 1/2 feet high, which is also the legal limit. The thing that makes it somewhat unique is that the expandable side, to my knowledge, is the largest ever put in a television truck. It's 49 feet of the 53, and it comes out 5 1/2 feet. So it's a very large truck, but a single expansion."

Digital video meant digital audio, because, explains Gepner, "It became excruciatingly clear that creating an analog layer for audio was the kiss of death, from a signal and latency standpoint. So we designed an entirely AES truck that can use and generate both discrete AES and embedded audio. To my knowledge, it's the first major production truck to take that route."

That offered one distinct advantage. "We were able to realize some real weight saving in the truck by using digital audio." Saving weight was crucial in a truck that contains more than 400,000 feet of cabling. "That's over 80 miles of cable," Gepner points out.

"We ship the signal on miniature coax, unbalanced," he continues. "We used transformers where we needed to balance. We went unbalanced for the weight saving, in the connectors, that are BNC, the patch panels and the cable itself. It also simplified the wiring of the truck."

HD4 has gone straight into service, thanks to a long-term commitment from ABC Sports and sister channel, ESPN. The channels' needs helped dictate the equipment complement, which not only includes the more traditional Dolby Pro Logic II and AC3 encoders, but also the SRS Circle Surround encoders in the control booth's overhead bridge. "That was one of the requirements for ESPN," confirms Gepner, who worked with ESPN remote audio consultant Ron Scalise on the gear list. "Ron is one of the driving forces behind [SRS'] growth. He's done great things for them."

Gepner also singles out the Dolby DP570 Audio Tool for particular praise. "Wonderful box! One of the problems with surround was always getting assurance that you have a good stereo and a good mono mixdown. Previously, it resulted in you having lots more speakers than you wanted to have. This simplifies that whole process."

If there is a downside to the new truck's design, it is that "there's still a pretty steep learning curve," observes Gepner. "Just the nomenclature is unique. People in the field end of the television production industry confuse embedded audio with AES audio, thinking AES, by necessity, is embedded. So we're having as many discussions and holding as many seminars, formal and informal, as we can manage. The good news is, the majority of engineers get it very quickly."