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This paper presents the results of flight tests conducted in August 2015. During these flight tests, an OFDM-like sequence in the 902–928 MHz ISM band is used to characterize air-to-ground propagation of the 960–1215 MHz ARNS band. The paper gives a brief overview of the measurement setup and procedures, followed by the channel characterization results and an assessment of its applicability to aviation...
C/A code cross-correlation affects signal acquisition and tracking in global positioning system (GPS) receivers. This paper investigates the cross-correlation–induced tracking errors, which can be substantial when the two Doppler frequencies are apart by an integer number of kilohertz. Carrier smoothing is an effective mitigation against the pseudorange errors, although the residual could still be...
This paper proposes a novel batch acquisition method for eDME Carrier Phase based on non-uniform DFT. The theoretical false acquisition, failed acquisition, and wrong acquisition upper bounds are derived analytically and validated by Monte Carlo simulations. Actual flight test data recordings suggest the existence of substantial RF interference. Two algorithms are proposed to mitigate this interference...
Ionosphere scintillation is a natural interference encountered by RF signals propagating through the ionosphere. It can affect the performance of Global Navigation Satellite Systems (GNSS) signals and receivers. Since 2009, our research team has established several ionosphere scintillation monitoring and data collection system in Alaska, Singapore, and Hong Kong to collect both naturally occurring...
High-accuracy Total Electron Content (TEC) measurements are important for several applications, including GNSS time transfer with accuracies better than 10 ns. In addition, it is important to provide uncertainty estimates to algorithms that use the TEC measurements. Dual-frequency TEC errors are dominated by satellite inter-frequency biases, satellite inter-code biases, receiver inter-frequency biases,...
• Enhanced DME capable of meeting the most stringent Navigation and Surveillance accuracy and integrity requirements (RNP 0.3, NACp-8, NIC-7) — Current performance provides a factor of 10 margin compared to requirements • Enhancements transparent to legacy DME/N user • DME transponders require better (stratum-1) frequency reference and beat signal broadcast Other APNT requirements: • Authentication,...
The objective of this paper is to present and compare performances of several time-frequency analysis algorithms that characterize and associate ionosphere scintillation events focusing on carrier phase measurements obtained from three relatively close spaced antennas in Alaska. The results will be used to derive plasma drift velocity and estimate the 2-dimension size of the scintillation patches...
This paper focuses on using an image-based optical sensor (e.g. a digital camera) to estimate relative position and attitude without the explicit dependence on Inertial measurement Unit (IMU) gyro measurements, thus, avoiding sensitivities to gyro drift errors. The method uses a priori known point features and is an alternative to existing resection methods used in photogrammetry that can be easily...
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