Carrier Phase Tracking of Weak Signals Using Different Receiver Architechures
Carrier Phase Tracking of Weak Signals Using Different Receiver Architectures
M.G. Petovello, C. O’Driscoll and G. Lachapelle Position, Location and Navigation (PLAN) Group Department of Geomatics Engineering Schulich School of Engineering University of Calgary lock indicator values and carrier phase-based positioning quality were compared. Unexpectedly, the vector-based receiver did not perform very well and more work is needed to understand why this is the case. Of the remaining receivers, the ultra-tight receiver performed best, the estimator-based receiver performed second best and the standard receiver performed the worst. The ultra-tight receiver provided about 7 dB and 3 dB of sensitivity improvement over the standard and estimator-based receivers. INTRODUCTION High-sensitivity GNSS (HSGNSS) receivers are capable of providing satellite measurements for signals attenuated by approximately 30 dB (Fastrax 2007; SiRF 2007; ublox 2007). This capability is impressive and extends positioning applications dramatically. However, the focus of HSGNSS is generally on pseudorange measurements, thus limiting obtainable positioning accuracy to the order of tens of meters. In contrast, real-time kinematic (RTK) positioning capability (i.e., centimeter-level) in degraded environments has not received as much attention, even though many systems require – or could benefit from – such high positioning accuracy. Some potential benefits of RTK positioning include precise relative positioning of two (or more) vehicles (e.g., for autonomous vehicle operation), precise relative motion over time (e.g., for system/sensor calibration) and enhanced personal navigation/personnel tracking accuracy. Even if RTK positioning is not possible, the use of a float ambiguity solution (instead of fixed ambiguity solution with RTK) would provide tremendous improvements over pseudorange-based algorithms, primarily in terms of multipath mitigation. Unfortunately, carrier phase tracking requirements
M.G. Petovello, C. O’Driscoll and G. Lachapelle Position, Location and Navigation (PLAN) Group Department of Geomatics Engineering Schulich School of Engineering University of Calgary lock indicator values and carrier phase-based positioning quality were compared. Unexpectedly, the vector-based receiver did not perform very well and more work is needed to understand why this is the case. Of the remaining receivers, the ultra-tight receiver performed best, the estimator-based receiver performed second best and the standard receiver performed the worst. The ultra-tight receiver provided about 7 dB and 3 dB of sensitivity improvement over the standard and estimator-based receivers. INTRODUCTION High-sensitivity GNSS (HSGNSS) receivers are capable of providing satellite measurements for signals attenuated by approximately 30 dB (Fastrax 2007; SiRF 2007; ublox 2007). This capability is impressive and extends positioning applications dramatically. However, the focus of HSGNSS is generally on pseudorange measurements, thus limiting obtainable positioning accuracy to the order of tens of meters. In contrast, real-time kinematic (RTK) positioning capability (i.e., centimeter-level) in degraded environments has not received as much attention, even though many systems require – or could benefit from – such high positioning accuracy. Some potential benefits of RTK positioning include precise relative positioning of two (or more) vehicles (e.g., for autonomous vehicle operation), precise relative motion over time (e.g., for system/sensor calibration) and enhanced personal navigation/personnel tracking accuracy. Even if RTK positioning is not possible, the use of a float ambiguity solution (instead of fixed ambiguity solution with RTK) would provide tremendous improvements over pseudorange-based algorithms, primarily in terms of multipath mitigation. Unfortunately, carrier phase tracking requirements
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