GUY NORRIS / LOS ANGELES
Lufthansa Technik is installing the first "black label" mechanically-steered Connexion by Boeing broadband satellite-communication antenna on a Lufthansa-operated Airbus A340 following completion of the bulk of flight tests on Boeing's 737-400 flying testbed.
The Mitsubishi Electronics-built antenna has been developed to improve coverage for the Connexion real-time internet/ intranet and email service above 65° latitude, and will be standard equipment for all new installations. The original phased-array antenna will continue to be offered for "government" platforms, says Connexion by Boeing director of system development Ed Laase.
Flight tests of the initial "red label" experimental antenna hardware began in August 2003, while tests of the current "black label" pre-production unit started in December, says Laase. The latest phase of tests has involved evaluation of how the antenna copes with "seamless hand-offs between American, North Atlantic and European satellites. We are going from one continent to another, and no-one else is doing that sort of hand-off."
The antenna uses data from the aircraft's inertial navigation system to establish a rough pointing direction before implementing a fine-tuning "step-tracking" process to lock on to the satellite.
In step tracking, the algorithms in the processor sequentially compare the amplitudes in the signal lobes, and within milliseconds home in on the satellite by focusing on the zones of maximum signal strength. The antenna can track down to zero degrees, which means "we can get low [angle] coverage at high latitudes up to 80° north", says Laase, who adds mean time between failure for the system is expected to be 25,000h.
The antenna is packaged in a fairing measuring around 2.3 x 1.1m (7.5 x 3.6ft), or roughly 0.75m longer than the phased-array unit.
"The system is good for aircraft the size of the 717 and larger," he says. The system will also support "private voice" connectivity which allows for voice communications. "Airlines are also showing interest because it is another voice channel," he adds.
For smaller business jet applications, Connexion by Boeing is working with Rockwell Collins on a similar steerable system under the "Collins Exchange" programme. Testing of the 0.3m Collins antenna unit is due to begin later in 2004 with service entry planned for the first half of 2005.
Source: Flight International
