Raytheon Company

Ender E Barillas

Benjamin P Dolgin

James C Zellner

Brian Filarsky

Matthew E Gann

William F Dixon

Arnaldo J Colon

Jason Kyle

Garabed P Hagopian

A GNSS hostile environment simulator for accurate real-time processor & hardware in the loop (PHIL) simulations of a multiple antenna GNSSR/AJ system models antenna effects over the entire signal bandwidth allowing direct injection of the RF into the GNSSR. Computational efficiency is achieved by applying the antenna patterns in the frequency domain. To preserve the integrity of the antenna signals, the transmitter signals are generated over an extended period to push any residual ringing outside the update window. Efficiency is further enhanced by using a combination of single-precision and double-precision floating-point units to generate the samples of the transmitter signals with single-precision floating-point. All subsequent calculations are then computed in single-precision.

Global navigation satellite system (GNSS) hostile environment simulation

Computationally efficient mixed precision floating point waveform generation takes advantage of the high-speed generation of waveforms with single-precision floating point numbers while reducing the generally unacceptable loss of precision of pure single-precision floating point to generate any waveform that repeats in 2&#x3c0;. This approaches computes a reference phase in double precision as the modulus of the phase with 2&#x3c0; and then computes offsets to that value in single precision. The double precision reference phase is recomputed as needed depending on how quickly the phase grows and how large a machine epsilon is desired.

Computationally efficient mixed precision floating point waveform generation

Technology for determining a geographical location is described. A sequence of magnetic field gradient measurements can be identified for specific positions on the Earth that correspond to a path traveled by a moving platform. The sequence of magnetic field gradient measurements for the path can be compared to a reference magnetic field gradient map. A trajectory derived from the reference magnetic field gradient map that correlates to the sequence of magnetic field gradient measurements can be identified. The trajectory can have known geographical coordinates. The geographical location of the moving platform can be determined based on the known geographical coordinates of the trajectory.

Magnetic field gradient navigation aid

Technology for performing magnetic field gradient measurements is described. The magnetic field gradient measurements for specific positions on the Earth can be performed from a moving platform. The magnetic field gradient measurements can be identified as being affected by a level of error that exceeds a defined threshold. A correction value can be generated to compensate for the error in the magnetic field gradient measurements. The correction value can be applied to the magnetic field gradient measurements in order to obtain magnetic field gradient measurements with a reduced level of error.

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Tucson, AZ, United States of America

Ender E Barillas