All-digital chopper lifts off for WPIX

Mar 5, 2001  •  Post A Comment

WPIX-TV is based in the Daily News building at 42nd Street and Second Avenue in Manhattan. But the Tribune Co.-owned WB station can clearly cover news live from as far away as the tip of Long Island, Poughkeepsie, N.Y., Atlantic City, N.J., and out west to the Poconos in Pennsylvania, thanks to its new all-digital news helicopter.
The chopper is leased from HeliNet. But the electronic equipment on board was purchased and outfitted by the station from vendors as diverse as FLIR Systems (camera ball package), Tandberg Television (encoder/modulator), NuComm (transmitter), NSI (antenna pod and microwave control system) and Sony (BVP 570 camera and digital switcher). Canon provided the 1000 mm lens for the BVP 570. Other cameras on board (which connect to the Sony switcher) include three lipstick cameras outside and two talent cameras inside.
Air 11 flew its all-digital maiden on-air run Feb. 8. It had been operating as a hybrid digital-analog craft since its June 5 premiere on “The WB11 Morning News” show. Between the two dates, the station worked out the kinks, including navigation of the “Bermuda Triangle” of dead spots, the New York Harbor.
It was the sweet culmination of a two-year project to get multipath-free reception with perfectly clear video and audio.
Mike Gano, the station’s director of engineering and operations, said the new chopper meets three main goals: better signal consistently from the platform, highest-quality pictures, and ability to read a license plate on a car from 800 feet.
“There was a crystal-clear picture to viewers at home the first day out, so we tried some distance shots,” recalled WPIX Engineering Manager Ralph Augenfeld. “We went up the Hudson River almost 50 miles without breakup, refueled and went west to the Delaware Water Gap [Pennsylvania border] and over a mountain range to a Pocono ski resort [about 80 miles west of the receiver site]. And that’s air miles-which doubled to tripled our traditional distance.”
The next day was even better. Air 11 headed east to the tip of Long Island, about 110 miles (98 air miles away) to the Montauk Point light house, catching sight of Connecticut across the Long Island Sound. According to Mr. Gano, “We ran out of Long Island before we ran out of signal.”
Both Mr. Gano and Mr. Augenfeld attribute much of their success to COFDM, a transmission technique that splits bandwidth into many narrow subband channels, which are then modulated by a low-rate data stream.
“One of the main advantages of COFDM vs. analog FM [the traditional microwave signal used on mobile units] is that all the ghosts are eaten up like Pac-Man,” Mr. Augenfeld said. “What normally added noise to the picture-signals arriving late to the receiver due to bounces off the millions of obstructions from the Manhattan skyline-are now all added together to improve the picture. Each bounce actually gives you more signal energy.”

Tandberg Television spokesman Marc Genin likened this Pac-Man approach to improving billiard shots, comparing the multipath problems of TV signals bouncing off obstacles to caromed billiard balls. What Tandberg’s encoding and COFDM modulation system does, he noted, is split the picture into more manageable pieces, much the same way that increasing the number of billiard balls and angles on the table would increase one’s chances of banking a shot.
“We encode 1,705 different channels so the receiver knows what to look out for,” he said, adding that this betters the odds of a signal getting through 1,705:1. “We built a frame interleaving system so you don’t get any break up-we’ve tamed the microwave.”
In addition to improving the picture, COFDM also calmed the fear of running out of microwave bandwidth, which has nagged broadcasters for the past couple of years.
“Two years ago, the FCC started rumblings about how broadcasters would have to drastically reduce the spectrum in the 2 GHz region,” Mr. Augenfeld said. “Analog transmitters need wider bandwidth to operate reasonably well. COFDM can perform much better with half the bandwidth.”
In fact, Mr. Augenfeld noted only two drawbacks to the digital scenario.
First, with digital technology either you have a picture or you don’t. And second, the slight delays because of compression-which are similar to pauses experienced in satellite relays-take the fun out of news team banter.
On Feb. 27, Tandberg Television jetted from London to New York to tweak the modulation software, improving delays from an unacceptable one second to about a half-second.