Advanced Family of Software Simulators

Andrew Brown and Suman Ganguly

Abstract:	High fidelity robust testing of modern receivers demands highly accurate signal generation that is commensurate with complex environmental conditions. Demands of the modern test and simulation systems can only be met with a flexible signal generation scheme that will faithfully reproduce subtle features of the signal wavefront. The Center for Remote Sensing, Inc. (CRS) has developed the world’s most sophisticated, comprehensive, and accurate signal simulator for Holloman AFB. The Advanced GNSS Hybrid Simulator (AGHS) is the most comprehensive and advanced GNSS simulator in the world. It is modular, flexible, and provides extremely precise simulated signals for almost all available constellations (GPS, GLONASS, Galileo, EGNOS, etc.). It provides a true replica of the signal wavefront under wide ranging user dynamics. The simulator generates live RF signals for different bands and provides a faithful reproduction of all aspects of signal generation (waveform, code, carrier, antenna, power, source motions, orientation, etc.) and receiver configuration (antennas, receiver dynamics, etc.). Twenty-four jammers with complex waveforms, independent motion, and with dynamic range of 120 dB are built in. Wavefront fidelity is maintained both for the jammers as well as for the navigational signals. A variety of jammers (radar, communication, jammer, navigation, etc.) can be built in and additional waveforms can be added as required. High fidelity and precision is maintained throughout the system (accuracy of 1 mm is achieved) and special care in terms of analog portions, particularly those involving code and phase relationships, is maintained. A particularly novel feature of the simulator is a built in calibration system to ensure the code and phase accuracies of the order of 1 mm. Such precision has never been achieved before. A special calibration system (patent pending) has been developed to ensure such accuracies. The simulator utilizes a large effective bandwidth for all the signals. State of the art digital technologies are used to maintain such a large bandwidth. This ensures the signal qualities and faithful reproduction of subtle features. This also allows all the current and proposed waveforms to be reproduced and the interactions of both in-band and out-of-band signals to be investigated. The modernized architecture of the AGHS has allowed us to provide smaller modularized simulators for individual constellations. These small simulators for GPS, GLONASS, Galileo, Beidou, Jammers, etc. all share the precision and high fidelity of the AGHS. They allow high dynamics (up to 1000 g) and unprecedented accuracies (mm level). The simulators utilize a real time software based architecture pioneered by CRS. The simulators provide both digital and RF outputs where any combinations of signals can be combined. The simulator responds to external stimuli in less than 5 ms, enabling hardware in the loop (HWIL) simulations along with remote networking capabilities. The simulators have an intuitive and user friendly graphical user interface (GUI) and several options are built in for operator control. All the signals and internal signal structure can be monitored in real time. The software based simulator also allows unconventional situations and environments (ionospheric scintillation, nuclear effects, plasma thruster effects, etc.) to be precisely simulated, which was never possible using conventional simulators. We present the description and performance of this simulator.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	1265 - 1276
Cite this article:	Brown, Andrew, Ganguly, Suman, "Advanced Family of Software Simulators," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 1265-1276.
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