Signal Authentication

Global Navigation Satellite Systems (GNSS) are no longer only utilised for Military purposes, such as marine and aircraft navigation, which are secured and encrypted. GNSS are becoming more prevalent in day-to-day civilian life for example, vehicle and even phone theft monitoring, cargo tracking, critical time synchronisation for utility, telecommunications, banking and computer industries and apps requiring positioning such as google maps available on mobile phones owned by a large proportion of the western world, which are not secured or encrypted [1]. GNSS is a generalised term encompassing all forms of architecture that combine Position Navigation and Timing (PNT) with map and other data such as weather [2]. To work accurately these systems must be able to accurately and precisely determine one's location and orientation and such determine current and desired position while applying corrections to course, orientation and/or speed accordingly while maintaining accurate and precise time from a standard Coordinated Universal Time (UTC). [4] Unlike jamming signals which deny the positioning capability of equipment, spoofing signals induce counterfeit signals/information by mimicking temporal and spectral characteristics of authentic signals such that the GNSS equipment that is not aware of the attack. [4] has categorised the spoofing techniques into signal generators (basic) and receiver based (more complex). These are discussed and compared as well a current countermeasures including receiver signal/absolute power/clock monitoring and mitigating methods such as Vestigial Signal Detection, Multi Antenna Beam Forming/Null Steering and Receiver Autonomous Integrity Monitoring (RAIM). The aim of this project is to find a reliable method of signal authentication and spoofing signal mitigation, this will most likely (initial resoning) involve a combination monitoring of receiver clock stability/offset via network monitoring and/or RAIM, real-time digital signal processing (DSP) techniques and angle of arrival techniques using multiple antennas or phased array antennas with beamforming and nulling capabilities The reasoning behind this being that for this being that angle of arrival (AOA) techniques are strong and when combined with beam steering can nullify any spoofing signal however, they may be overcome with sophisticated spoofing techniques and thus as every spoofing attack will influence receivers' clock offset, the monitoring of this will provide a suitable failsafe if/when AOA fails.