C Band Telemetry at Airbus Flight Test Centre

Abstract

Airbus is authorized to use S-band for Telemetry transmission until 2015. In October 2011, the decision was taken to move to C-band in 2013, to cope with Airbus development aircraft planning. The objective was a real challenge for 2 main reasons: C-band channel was not characterized in Airbus transmission environment and it was necessary to validate the propagation performance for Flight Tests uses. The selected solution is based on Coded Orthogonal Frequency Division Multiplexing (COFDM) modulation. There was no existing solution so it has led the Airbus Test Centre to drive the development of its own C Band solution. C-band telemetry at Airbus has been tested and evaluated in flight from April 2012. The first goal was to check the coverage and the impact of the bad weather condition. Besides, it was necessary to characterize the channel to choose the optimised parameters for the waveform in the Toulouse Blagnac environment. This selection of parameters allows the high quality and increased data rate required for Airbus Telemetry to be reached. The test results consolidated the choice of a COFDM modulation, when given the high sensitivity to multipath of usual Frequency Modulation in the airport environment full of buildings and aircrafts. Moreover, it has been possible to reach a similar quality to the S-band telemetry systems, thanks to a fine tuning of the waveform parameters, and tracking system. Deployment of the system by modifying 8 reception antennas and 12 development aircrafts was done over a span of 4 weeks in January 2014. No impact on Airbus A350 certification campaign occurred due to close collaboration with Flight Test Operations. The new Telemetry system enables an increase of telemetry capabilities in the future, especially the data throughput, simplified remote control and monitoring. This experience is an opportunity to set up a new standard.