Loran Aviation Receiver and RF Simulator Development

B. Peterson, K. Dykstra

Abstract:	The U. S. Department of Transportation (DOT) has accepted the findings and recommendations of the Volpe National Transportation Systems Center (VNTSC) report on GPS Vulnerability in general and specifically the need for a backup to GPS in safety critical applications. However, for Loran to be accepted as a redundant navigation system for aviation, it must meet the accuracy, availability, integrity, and continuity standards for Required Navigation Performance 0.3 (RNP 0.3). The Loran Integrity Performance Panel (LORIPP) is assessing Loran’s potential to meet the RNP 0.3 performance. Part of that assessment is to determine if a practical receiver can be designed to meet the RNP 0.3 requirement, what the Minimum Operational Performance Standards (MOPS) for that receiver will be, and to develop the capability to test whether receivers meet those MOPS. In addition consideration has been given to modulating the Loran signal to broadcast Loran or GPS augmentation data such as the broadcast of the WAAS message or other signal modifications to enhance multi-chain, master independent operation and solution for absolute time from the Loran signal. Testing receivers that exploit these signals through use of the existing operational network of Loran transmitters is problematic. This paper describes a combination receiver and RF simulator development effort in support of the LORIPP’s assessment as well as other initiatives. LORIPP analysis thus far has indicated that RNP 0.3 performance can be achieved if the receiver can average pulses over a long enough time period. A critical issue is whether the desired dynamic performance can be maintained when averaging over the required number of pulses. The RF simulator produces either electric or dual channel magnetic field signals, and either standard Loran or modulated signals. The scenario is driven either in real time from the keyboard or from a stored file. The noise is a combination of Gaussian and impulse noise and is presently based on Technical Standard Order (TSO) C60B. A separate effort is focused on a new noise model. Blink or off-air conditions are possible parts of the scenario. The chains are synchronized to enable multi-chain receiver operation. Skywaves are simulated as well. The receiver provides a test bed to evaluate candidate tracking algorithms to meet RNP 0.3 performance and maintain dynamic performance, algorithms to detect and correct cycle errors, and algorithms to determine integrity and accuracy parameters.
Published in:	Proceedings of the 2003 National Technical Meeting of The Institute of Navigation January 22 - 24, 2003 Disneyland Paradise Pier Hotel Anaheim, CA
Pages:	755 - 766
Cite this article:	Peterson, B., Dykstra, K., "Loran Aviation Receiver and RF Simulator Development," Proceedings of the 2003 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2003, pp. 755-766.
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