Journal of Global Positioning Systems

Vol. 10, No. 2, 2011

Journal of Global Positioning Systems
Vol. 10, No. 2, 2011
ISSN 1446-3156 (Print Version)
ISSN 1446-3164 (CD Version)

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JGPS Team Structure, Copyright

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Table of Contents

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Shi Hu-li(1), Jing Gui-fei(2) & Cui Jun-xia(1)
(1) National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012, China
(2) National Remote Sensing Center of China, Ministry of Science and Technology of the P.R. China, Beijing, 100862, China

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In order to further expand and enhance the level of applications of satellite navigation, three new systems are proposed on the basis of successful application of existing satellite navigation systems: a two-way satellite communication and navigation system which is based on a two-way satellite communication transmission link, a satellite-assisted ground mobile communication and navigation system and an air-ground communication cooperation multi-system multi-mode positioning system. Key technologies for achieving breakthroughs and implementation of the three new systems are also described, including deep integration of navigation signals and communication signals, a compared measurement technique, and our method to improve constellation GDOP. Some applications of these new systems, in the fields of high-precision measurement, emergency rescue and equipment real-time monitoring, are introduced.

Binghao Li(1), Shaocheng Zhang(2), Andrew G Dempster(1) and Chris Rizos(1)
(1) School of Surveying and Spatial Information Systems, University of New South Wales, Sydney, Australia
(2) SPACE Research Centre, RMIT University, Australia

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Regional Navigation Satellite Systems (RNSS) are being developed by Asian countries. The Asia-Oceania region becomes a hotspot that the maximum number of navigation satellites can be "seen". There will be a great impact of the RNSSs on positioning in this region. This paper introduces the Asian RNSSs, discuses single point positioning and differential positioning using RNSSs and analyses the combination of GPS and RNSS for urban canyon positioning by simulation.

Wen Zhang(1) Mounir Ghogho(2,3)
(1) National University of Defense Technology, China
(2) School of Electronic and Electrical Engineering, University of Leeds, UK
(3) International University of Rabat, Morocco

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GPS signal detection using hypothesis testing analysis are given by using the generalized likelihood ratio test (GLRT) approach, applying the model of intermediate frequency (IF) GPS signal of one satellite in white Gaussian noise. The test statistic follows central or noncentral F distribution and is nearly identical to central or noncentral chi-squared distribution because the processing samples are large enough to be considered as infinite in GPS acquisition algorithms. The probability of false alarm, the probability of detection and the threshold are affected largely when the hypothesis testing refers to the full PRN code phase and Doppler frequency search space cells instead of to each individual cell. The performance of the test statistic is also given with combining the noncoherent integration. Given the probability of false alarm to achieve a desired probability of detection, examples are illustrated to determine the relations among the threshold, the coherent integration time, the number of noncoherent integration and signal to noise ratio.

Al-Shaery, A., Lim, S., and Rizos, C.
School of Surveying and Spatial Information System, the University of New South Wales, Sydney, NSW, Australia

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This paper thoroughly investigates several approaches to implementing the GNSS network-based real-time positioning technique, which requires the estimation of atmospheric corrections on an epoch-by-epoch basis for RTK. In this study, a network of Continuously Operating Reference Stations in New South Wales, known as CORSnet-NSW, was utilised to: 1) obtain atmospheric residuals from each reference station, and 2) determine network correction for a rover operating in the area covered by the network using several interpolation methods. Applying the atmospheric corrections obtained by the interpolation methods, "synthetic" measurements at a virtual reference station are generated and then used for rover positioning. Field tests with various master-rover baseline lengths ranging from 21 to 62km indicate that a range of 1.9 to 6.5cm of horizontal positioning accuracy is achieved. In this study, the performance of geostatistical (Oridinary Kriging Method and Least Squares Collocation Method) and deterministic (Linear Combination Method, Linear Interpolation Method, Low-order Surface Method and Multiquadric Surface Fitting Method) interpolation methods used in GNSS network-based RTK positioning were also analysed in order to identify the optimal method for mitigating atmospheric effects for real-time kinematic applications under different network geometries.

Jinghui Wu and Andrew G. Dempster
School of Surveying and Spatial Information Systems, University of New South Wales, Sydney 2052

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A new unambiguous discriminator similar to a conventional Double Delta correlator is tailored for sine-phased BOC(1,1) signal tracking. It is shown in this paper that it has efficient multipath mitigation at the cost of degraded noise resistance due to correlation loss of using waveform subtraction. Its multipath performances is evaluated in both coherent and dot-product type non-coherent structures. The advantage of dot-product type discriminator structure for multipath resistance is shown. Tracking c ode jitters are examined theoretically and empirically. A new simplified jitter expression is provided to facilitate the comparison of relative noise performance for various Strobe Correlators with the proposed discriminator, without considering the effect of bandlimiting.

Kyle O'Keefe(1), Gérard Lachapelle(1), Antonella Di Fazio(2), Daniele Bettinelli(2)
(1) Dept. of Geomatics Engineering, University of Calgary Schulich School of Engineering, 2500 University Dr. NW, Calgary, Alberta, Canada, T2N 1N4
(2) Telespazio S.p.A., 965 via Tiburtina, 00156 Rome, Italy

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Receiver Autonomous Integrity Monitoring is most often described using an example where six pseudoranges estimate four unknowns. In this paper, the implications of using only five satellites are investigated. An earlier paper showing that least-squares estimations involving one degree of freedom with equally weighted observations always result in residuals with a value of ±1 is reviewed. The results from this previous work are generalized for the case of weighted observations and a priori knowledge of measurement variance. The new general result is that, when there is one degree of freedom, the standardized residuals always equal ± the square root of the estimate variance factor. This result is then demonstrated using an epoch of real data collected during a vehicle navigation test in an urban canyon where six and then five pseudorange observations are available.

Jinling Wang(1), Nathan L. Knight(1) and Xiaochun Lu(2)
(1) University of New South Wales
(2) The National Time Service Center, Chinese Academy of Science

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With the development of GPS, GLONASS, Galileo, Compass, QZSS and the IRNSS, there has been growing interest in the development of system independent receivers. However, one of the problems encountered in system independent receivers is in the different time systems employed by each of the satellite navigation systems.

To overcome this problem it has become a standard practice to solve for the time differences within the receiver's navigation solution via a combination of receiver clock corrections and/or time offsets. While this technique overcomes the problem of the different time systems, it is at the cost of a satellite from each additional time system. Despite this, the numerous studies that combine multiple satellite navigation systems this way have still found that there are significant benefits in improved accuracy, integrity, continuity and availability.

To enhance interoperability though satellite navigation system providers are intending to measure and transmit the time offsets to other time systems. The subsequent use of these time offsets will provide a more accurate navigation solution than without them. However, the problem with using the time offsets is that they pose an additional integrity risk because they are also potential sources of faults. However, with the use of the time offsets for multiple constellation solution, a proper Receiver Autonomous Integrity Monitoring method has not been developed.

Thus, mathematical models to account for the time differences with and without the time offsets are presented in this paper. Furthermore, the model that incorporates the time offset allows the application of Receiver Autonomous Integrity Monitoring to detect the presence of any faults within the time offsets. The reliability of the linear models is then compared using GPS and GLONASS geometry in terms of the Minimal Detectable Biases, Protection Levels and the correlation coefficients. The results of this analysis indicate that a more reliable solution can be obtained with the time offsets because they are additional measurements.

Corporate Members of CPGPS

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Instructions to Authors

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CPGPS Management Team (2011) Structure

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