NovAtel's Annual Journal of GNSS Technology Solutions and Innovation

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Page 40 of 51

Navwar 2014 For more Solutions visit velocity 41 Anti-Jam Antennas–Null Steering. Anti-jam an- tennas protect against GNSS interference by dynamically adjusting the effective antenna gain pattern and steering 'nulls' in the gain pattern towards the direction of the interferer. This prevents the majority of the interfering power from entering the GNSS receiver. No- vAtel's GPS anti-jam technology uses multiple antenna elements and digital null forming an- tenna electronics, allowing a connected receiver to continue to provide a PNT solution in the presence of interference. Multi-Frequency/Multi-Constellation GNSS. Multi-fre- quency receivers also provide a means of protect- ing against interference. For example, if interfer- ence in the L1 frequency band around 1575 MHz is completely jamming GPS and GLONASS, it is usually possible to continue to calculate a PNT so- lution using the L2 GPS and GLONASS frequency band around 1227 MHz. Multi-Sensor Navigation. If the duration of the interference is short, an integrated solution, like NovAtel's SPAN® technology, which deeply couples a GNSS receiver with an Inertial Mea- surement Unit (IMU), can be used to bridge the GNSS outages. In general, the better the quality of the IMU, the better the PNT solution during these outages. Additional sensor inputs such as odometer or altimeter inputs can be used to further aid the PNT solution, and there is a growing trend to use low-frequency RF systems like eLoran in conjunction with GNSS and other sensors. Protection techniques for intentional interference In March 2014 the Canadian Army conducted trials of NovAtel's GPS Anti-Jam Technology (GAJT ® ) in an operational environment. The successful trials, which were done under the auspices of the Build in Canada Innovation Program (BCIP), showed that GAJT protected the Position, Navigation & Timing (PNT) systems of the vehicle even while there was GPS jamming in action. The Light Armoured Vehicle III Observation Post Variant (LAV III OPV) was chosen for its particular PNT needs, especially for artillery target acquisition equipment which was shown to operate with GAJT to the same level of precision and functionality as with the standard GPS antenna. FIELD TRIAL SUCCESS Photos courtesy of Canadian Army's Directorate of Land Requirements (DLR).

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