On the Air In the Air with Peter Greenberg


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As soon as the lighted “fasten seatbelt” sign above everyone's head dimmed, Peter Greenberg's team quickly began preparing for his regular Saturday morning radio show, which was scheduled to begin in about an hour. But unlike most Saturdays, Greenberg, host of Travel Today with Peter Greenberg, was about to broadcast his show from a regularly scheduled flight of a Lufthansa Airbus 330 jet flying from Frankfurt, Germany to New York City. Flying at 35,000' at about 600mph, this would be the first live radio program from a commercial airliner. Until now, technology was not advanced enough to accommodate a radio broadcast such as this.

“I remember being in the cockpit of a Pan Am 747 in 1985, and we arranged for me to do a live radio report on the polar route from London to Los Angeles,” said Greenberg. “It was a scratchy, weak signal, relayed through Stockholm radio to the station back in California. It lasted just four minutes until we lost the signal.”

But 21 years later, on April 22, 2006, technology made it possible for Greenberg to broadcast for 2.5 hours discussing the travel industry, interviewing travel industry professionals and answering call-in questions from listeners.

This project was three years in the making. It began with Greenberg's engineer, Mike Worrall, calling about a half dozen technical departments of airlines, such as Singapore Airlines and Cathay Pacific, asking whether they had the ISDN technology to accommodate a broadcast from an airplane. Repeatedly the airlines would say that though many private business jets were equipped with ISDN capability — via services like Inmarsat Fleet 77 — no commercial airlines were equipped with this equipment.

Sky high Wi-fi

Technical Coordinator Mike Worrall on-board Lufthansa flight 406 with the Comrex Access for the Travel Today broadcast.

In late 2005, Lufthansa contacted Greenberg about a new system from Boeing that was being installed in its long-range fleet that was Internet-based. Connexion by Boeing allows high-speed wireless Internet access on many airlines operating international flights. Users can log onto the Internet via their laptops during the flight and surf the Web, check e-mail, listen to streaming music and even tunnel through VPNs to work. It accommodates all three standards of Wi-fi: 802.11a, 802.11b and 802.11g. Lufthansa calls its Internet portal Flynet.

There is a data transceiver and router in the front of the plane. There is also a reflector antenna that is located on top of the airplane. The dish, about the size of a fist, turns and there is reflector that raises and lowers to maintain contact with the satellite, depending on where the aircraft is en route. There are currently five ground stations around the world to receive the signal. From Frankfurt, the airplane was using the station in Switzerland. Before Greenberg's show began, it switched to a ground station in Littleton, CO.

The other piece of equipment that previously wasn't available, but made this broadcast possible, was Comrex's Access audio codec. This codec is capable of providing voice and music quality service over IP connections using what Comrex has dubbed “BRIC technology.” BRIC stands for for Broadcast Reliable Internet Codec and enables broadcasters to use a variety of commonly available Internet access points to broadcast high quality, real-time audio. The Access is capable of using widely available wired circuits such as DSL, cable, POTS and frame relay as well as wireless circuits such as Wi-fi, 1XRTT, Edge and 3G data networks.

Comrex shipped Boeing an Access and Boeing facilitated some tests using its network simulator. At this point, the tests were not aircraft-based, but the tests indicated that the equipment would work together. The biggest concern seemed to be possible contention from other Internet users on board the plane.

“Boeing was convinced that we could get wired Ethernet and that the data path available for the whole plane would be 128kb/s, which is much more than the Access needed,” said Tom Hartnett, vice president of engineering at Comrex.

Three weeks before the broadcast, Boeing informed Hartnett and Worrall that the Lufthansa fleet was not equipped with hard-wired Ethernet jacks at each seat, rather that their planes were “flying Wi-fi hotspots.” Hartnett suggested waiting until the fall when Comrex would have a portable unit available with built-in Wi-fi and battery power, but it was too late to turn back or postpone the broadcast at that point. As soon as Greenberg heard that the initial tests were a success, he scheduled the Lufthansa broadcast. So, Hartnett and Worrall configured a standard laptop PC with Windows Connection Sharing providing the Access a path to the Internet via the laptop's built-in Wi-fi.

One week before the official broadcast, Worrall created a test broadcast on an outbound flight between Los Angeles and Frankfurt while on his way to South Africa, which was the site of Greenberg's broadcast the week prior to the official airplane broadcast. Worrall and a Boeing engineer were on the plane while the engineering team at Comrex was standing by to participate in the test.

About 20 minutes into the test the captain of the Lufthansa flight approached Worrall demanding that he turn off the equipment. Passengers were complaining that they couldn't get on the Internet. The captain assumed it was Worrall's equipment causing the problem. In reality, the flight crew had failed to clear the system's credit-card authorization cache following the plane's previous flight. Each time a plane lands the flight crew must push a button that clears everything in the queue that is Internet-related. The crew had failed to do that.

Travel Today Host Peter Greenberg with Worrall during the initial connection of the Comrex Access.

When Worrall and two other passengers logged on, they filled the bandwidth. Because of this, Worrall had to stop testing the system.

“The good thing was that what I heard during those 20 minutes of testing was very positive,” Worrall said. “There was no break-up, it was very clean.”

The group decided to try another test on the flight from South Africa back to Frankfurt. Unfortunately, they encountered another problem. Lufthansa explained that the Flynet system had no coverage over most of Africa. Because Worrall was flying from southern Africa to Frankfurt, he would only get about two hours worth of testing time. And because he couldn't use the system during the last hour of the flight, because the crew would be busy preparing for landing and cleaning up, Worrall would only be allowed one hour of testing time.

The second test proved to be as solid as the first, even if it was only for an hour. Still, the path the audio would take from the airplane to New York during the live broadcast was complex.

Greenberg's show is syndicated from ABC Radio in New York and distributed via the ABC satellite system. Also, the studio that assembles all of the commercials, buffers and liners that are part of the show is at ABC in New York. But the weekend IT staff is limited. Had there been connection issues during Greenberg's broadcast, it might have meant dead air.

Because Worrall is the assistant chief engineer at ABC Radio in Los Angeles, he called on his colleagues to help. He installed the Comrex Access in Los Angeles instead of New York. The LA station had a dedicated T1 service with an analog, no delay path from ABC Radio LA to ABC Radio NY. He hooked the output of the Access to the T1, routed it to NY where they received the airplane audio. But then the signal had to be returned from NY to the plane. Because the path from LA to NY was only one way, Worrall had to find another way to get it back to LA. He used ISDN at G.722, which is a low delay algorithm. The quality didn't matter at that point, all Worrall wanted were the cues and caller audio; the low delay was most important. From the ISDN it was hooked back into the Access. From the Access, where it became Internet data again, it went to the satellite ground station in Littleton, CO, and went back to the plane. All of this took place in a little less than two seconds.

With the signal traveling all over the world, Worrall was concerned about possible single point of failure problems.

In terrestrial remotes using ISDN, the radio engineer can always fall back on the telephone line. On a plane there is no phone line. All Worrall had for a backup was a “best of” show on CD in New York. The board operator was instructed to use it if the signal from the plane was lost.

The transceiver and reflector antenna on top of the jet maintains contact with the satellite via a gyrostabilized mechanism.

Luckily, it was not needed. Greenberg's live broadcast was a success. Everything went smoothly — even more so than expected.

During the broadcast Greenberg was using about 24kb of the available bandwidth, which is about 20 percent. Because he was primarily uploading, or sending, rather than downloading like the majority of passengers on the plane, there were no bandwidth problems, nor did Worrall need to block-out bandwidth from the other passengers on the plane.

VoIP takes off

During his broadcast, Greenberg received a call from one of his film crew personnel who was on a flight from Frankfurt to LA. The film crew had been in South Africa with Greenberg the previous week and was heading home. With a laptop, the film crew logged on to the Internet using the Flynet/Connexion by Boeing access and listened to a live stream of the program. They were listening to the show on another airplane that was flying a completely different route, using the same technology that Worrall was using to broadcast Greenberg's program.

The film crew decided to call the show from the galley of the 747. They swiped a credit card, called the 800 phone number for Greenberg's program, talked to the board op in NY who told Greenberg in his headset “your video producer wants to talk to you from the airplane he's on going back to LA.”

“Now this technology is growing exponentially by the minute,” said Worrall. “Imagine talking to people on other planes. It's mind boggling.”

As everyone fastened their seatbelts and the flight attendants prepared for landing, some people looked relieved, others looked exhausted, but everyone understood the importance of the remote broadcast and its effect on the future.


Equipment List

Dell Latitude D610 laptop with onboard Wi-fi card
Mackie 1202 VLZ audio mixer
Comrex Access IP codec with BRIC
Sennheiser HMD 280 Pro headset




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