ADS-B degarbling and jamming mitigation by the use of Blind Source Separation

Abstract

Automatic Dependent Surveillance- Broadcast system is a pillar of the future air traffic system. Equipped aircraft utilize the on-board navigation system (based on the GPS unit) to calculate their position and velocity and then broadcast this information on a common RF channel using an on board emitter. Ground-based sensors receive these messages that are used by the ATC centers to produce an image of the traffic on the controller's display. This system uses a data-link protocol called “1090 Extended Squitter (1090ES)”: each aircraft periodically transmits messages PPM modulated on L-band (1090 MHz) with random access to the channel with a transmitter called transponder. This protocol is affected by two important limitations: the throughput of the channel is limited by the garbling effect (i.e. the reception of superimposed messages in dense scenario) and the fact that the 1090 MHz RF channel can be prone to jamming (that is the transmission of high power signals superimposing the aircraft messages). A method to mitigate these two effects using a multichannel ADS-B receiver and a Principal Component Analysis (PCA) based Blind Source Separation (BSS) technique is proposed in this work. The proposed method is evaluated using real signals both in jamming and garbling cases.