Tuning to the pulse of air traffic management

A signal receiver developed by Raytheon Systems could allow aircraft to fly closer to each other, increasing airport capacity and reducing flight times and fuel costs.

The station, which is being tested by the US Federal Aviation Administration and has been trialled by other air traffic authorities, is based on a high-performance decoder developed by the company’s engineers at Harlow.

The system uses advanced algorithms capable of detecting and decoding individual aircraft messages from among overlapping signals in heavily congested areas.

The technology, which operates at 1,090MHz, is designed to decode Automatic Dependent Surveillance-Broadcast (ADS-B) messages. ADS-B is an emerging technology that allows aircraft to broadcast information such as their position, track and ground speed, approximately once every second.

But as well as transmitting enhanced surveillance information to traffic controllers on the ground, it can also send this data to other aircraft, both in the air and on the runway. This could open up the possibility for so-called ‘free flight’ traffic management, in which pilots control their own separation from other aircraft.

ADS-B equipment is being fitted to all new and many existing commercial aircraft. But, according to Raytheon, no decoder has yet been developed that is capable of the high performance that will be needed as the skies become increasingly crowded. Sixteen million flights are expected by 2020 over Europe alone.

Martin Stevens, air traffic control systems consultant at Raytheon, said the technology is based on a new way of recognising the shape of signal pulses.

‘When there are overlapping signals the system makes a lot of measurements to the shape of the pulse to determine what is likely to be underneath. We can then pass on much more information to the error-correction system, to allow it to focus on areas that are most likely to be wrong,’ he said.

The company held trials at Frankfurt, considered one of the most tricky sites for radar, producing coverage of 250 nautical miles.