Application of Computer Modelling in Adaptive Compensation of Interferences on Global Navigation Satellite Systems

Application of Computer Modelling in Adaptive Compensation of Interferences on Global Navigation Satellite Systems

Valerian Shvets (National Aviation University, Ukraine), Svitlana Ilnytska (National Aviation University, Ukraine) and Oleksandr Kutsenko (National Aviation University, Ukraine)
Copyright: © 2019 |Pages: 42
DOI: 10.4018/978-1-5225-7588-7.ch014
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Modern society is characterized by the increased use of global navigation satellite systems (GNSS), which is inseparably linked with the interference immunity ensurance. The most effective way to protect against interferences is an introduction into the receiver structure of adaptive interference compensators. However, the most of proposed methods have been designed for radiolocation and communication and use a priori information about the transmitted signal. Since as structure of GNSS signal differs from the radar and communication systems, GNSS does not know the time-frequency structure of the useful signal in advance, which excludes the possibility of using a number of widely known methods. In this chapter, the authors propose a method, which does not use a priori information about a useful signal, and a new direct method for calculating the inverse correlation matrix of interference in adaptive antennas of interferences compensators.
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Analysis Of Global Navigation Satellite Systems Vulnerabilities

Modern society is characterized by the increased use of Positioning, Navigation, and Timing (PNT) services, which provide the basis for the effective functioning of many industries. In particular, PNT is an essential part of modern transportation systems, digital systems, telecommunications systems, command and control of precision weapons. The main suppliers (providers) of PNT services are Global Navigation Satellite Systems (GNSS), which are presented now by Global Positioning System (GPS, USA) (Federal Aviation Administration [FAA], 2013 a, 2013 b), GLObal NAvigation Satellite System (GLONASS, Russia) (Russian Institute of Space Device Engineering, 2008). The European Community sets up its own GALILEO system and China sets up BeiDow system for these purposes. GNSS provides with the data, using which one can determine the position of any user in space with an accuracy of one meter and by time with the accuracy of dozens and units of nanoseconds in any point of the globe and near-Earth space at any given time and in any weather.

After the first years of the intensive development and implementation of satellite navigation and time technologies, the more thorough analysis of the use of GNSS as the sole source of coordinate-time information, and more sober approach to the prospects of using GNSS begins. First, this is due to the GNSS vulnerability under the influence of unintentional and intentional interferences. The vulnerability of civilian GNSS receivers had been known for a long time (Littlepage, 1998; Pinker, Walker and Smith, 1998; Lyusin, 1998; Ward, 1994; Gilmore, 1998; Key, 1995; Bond, 1998), but receiver manufacturers and their users rarely consider it. Only when the US Department of Defense has intensified its activities related to the use of GPS in the military environment (NAVWAR), it became apparent that deliberate interferences to the civilian receivers should be taken into account as an important factor. Military testings conducted in the New York (United States) (Forssel and Olsen, 2003) area have shown, that a number of receivers installed on board of civil aviation aircrafts have lost the ability to track GPS signals (due to severe drops in the carrier-to-noise ratio of several GPS satellites’ L1 C/A code) at the approach phase at the International Newark Liberty Airport (NJ, USA). After an investigation by the FAA, it was discovered that a truck driver had installed a low-cost PPD on his vehicle (Colby et al., 1997).

The analysis of transport systems based on the use of GPS signals was carried out by (Winer, et al., 1996), (Wallis, 1999; Colby, 1997), (Report of the Commission to Assess United States National Security Space Management and Organization, 2001), (Corrigan, 1999). One of the most important and relevant reports on the research in this area was the Volpe Center Report on GPS vulnerability (John, 2001), which concluded that the GPS system, like other radio navigation systems, was vulnerable to unintended and intentional interferences and that such interference was a threat to security and can have serious consequences for the economy and the environment. The report concludes that the growing use of GPS in civilian infrastructure makes it an increasingly attractive target for hostile actions by individuals and groups. At the same time, the commercial availability of equipment for interference was detected (Forssel and Olsen, 2003; Rodgers, 1991).

Key Terms in this Chapter

Jamming (Electromagnetic): The deliberate use of unintended radiation, reradiation or reflection of electromagnetic energy for the purpose of preventing or reducing the effective use of a signal.

Antenna Array (or Array Antenna): A set of multiple connected antennas, which work together as a single antenna to transmit or receive radio waves.

Spoofing: Broadcast of signals, which can appear to be genuine GNSS signals.

Beamforming: A method used to create the radiation pattern of the antenna array by adding constructively the phases of the signals in the direction of the targets/mobiles desired, and nulling the pattern of the targets/mobiles that are undesired/interfering targets.

Meaconing: Re-broadcast of GPS signals in such a way as to create a stronger, but erroneous fix.

Global Positioning System (GPS): The global navigation satellite system provided by the United States of America. The GPS baseline constellation consists of 24 slots in six orbital planes, with four slots per plane. Three of the slots are expandable and can hold no more than two satellites. Satellites that are not occupying a defined slot in the GPS constellation occupy other locations in the six orbital planes. Constellation reference orbit parameters and slot assignments as of the defined epoch are described in the fourth edition of the GPS Standard Positioning Service Performance Specification, dated September 2008. As of that date, the GPS constellation had 30 operational satellites broadcasting healthy navigation signals: 11 in Block IIA, 12 in Block IIR and 7 in Block IIR-M.

Global Navigation Satellite System (GLONASS): The global navigation satellite system provided by the Russian Federation. The nominal baseline constellation of GLONASS comprises 24 Glonass-M satellites that are uniformly deployed in three roughly circular orbital planes at an inclination of 64.8° to the equator. The altitude of the orbit is 19,100 km. The orbit period of each satellite is 11 hours, 15 minutes, 45 seconds. The orbital planes are separated by 120° right ascension of the ascending node. Eight satellites are equally spaced in each plane with 45° argument of latitude. Moreover, the orbital planes have an argument of latitude displacement of 15° relative to each other.

Antenna Pattern (or Radiation Pattern): The directional (angular) dependence of the strength of the radio waves from the antenna or other source.

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