Time filter

Source Type

Sant'Ambrogio di Torino, Italy

Xuefen Z.,Nanjing Southeast University | Xiyuan C.,Nanjing Southeast University | Xin C.,Polytechnic University of Turin | Xin C.,Navigation Laboratory
Conference Record - IEEE Instrumentation and Measurement Technology Conference | Year: 2011

In this paper, MBOC (Multiplexed Binary Offset Carrier) Signal which is recommended as the optimized modulation on L1 (E1) frequency band by both US and EU sides in the future was studied. This paper carried on the detailed analysis to the new MBOC signal characteristic through the analysis of the power spectral density function. Then two multipath mitigation techniques based on DLL (Delay Lock Loop) - strobe correlator and narrow correlator with basic functionality and implementation were introduced. These two techniques were applied to mitigate the multipath's influence on MBOC signals. Simulation based on Matlab tool was analyzed and the performance was compared with the BOC signals. © 2011 IEEE.

Tang X.,Navigation Laboratory | Falco G.,Navigation Laboratory | Falletti E.,Navigation Laboratory | Presti L.L.,Polytechnic University of Turin
2014 7th ESA Workshop on Satellite Navigation Technologies and European Workshop on GNSS Signals and Signal Processing, NAVITEC 2014 - Proceedings | Year: 2014

New GNSS tracking architectures are becoming of scientific interest since the last decade. The traditional DLL/PLL tracking-loops have been progressively substituted by KF/EKF scalar tracking and VDLL/VDFLL vector tracking methods. In this paper we will analyze in depth the performance of a KF scalar tracking and VDFLL vector in case of signal outage. Differently from papers on the same topic, we will show how the performance of a KF, when used within the tracking stage during a signal's blockage, are strongly dependent on a proper setting of the noise covariance matrices Q and P of the system, otherwise cases of frequency false-lock can occur when the outage condition lasts for a long time. Conversely, a VDFLL vector tracking algorithm is able to provide more precise frequency and code-phase's estimations then the KF scalar in case of signal's unavailability, but its performance relies on the navigation solution. Therefore, the effects of the PVT accuracy on the estimation of the main tracking parameters are also presented in this paper. © 2014 IEEE.

Ugazio S.,Polytechnic University of Turin | Fantino M.,Navigation Laboratory | Lo Presti L.,Polytechnic University of Turin
Institute of Navigation - International Technical Meeting 2011, ITM 2011 | Year: 2011

This paper proposes an algorithm which adapts the Equivalent Noise bandwidth (ENB) of a Digital Phase Lock Loop (DPLL) in real time, with the objective to implement it within a fully software receiver. The algorithm is tailored for Global Navigation satellite System (GNSS) receivers, and can be easily implemented in a fully software platform. The algorithm aim is to reduce the dynamics stress error and the tracking jitter which affect the carrier phase estimate as much as possible. As the dynamic stress error is inversely proportional to the ENB, while the tracking jitter due to the noise is directly proportional to it, a trade-off is needed. This goal is reached by minimizing a cost function, containing the sum of two contributions depending respectively on the input dynamics and on the input noise. In particular the input signal frequency is considered linear, so the input dynamics is related to the input frequency slope. The minimum of the cost function is found by using some simplifications, necessary to achieve a computational speed suitable for real-time adaptation.

Falco G.,Navigation Laboratory | Campo-Cossio M.,Aerospace Unit | Puras A.,Aerospace Unit
2013 International Conference on Localization and GNSS, ICL-GNSS 2013 | Year: 2013

This paper presents the design of a truly low-cost multi-GNSS receivers /IMU navigation system that exploits the benefits of GNSS technology in attitude determination. The sensor package of the system consists of 4 single chipset receivers, 4 antennas, and one low grade MEMS IMU. Both parts, the GNSS and the IMU ones, are integrated by following a heading-constrained Tightly-Coupled approach, where inertial and GNSS raw measurements as well as GNSS computed heading are blended into an Extended Kalman Filter. To compute the attitude solution based on GNSS carrier phase measurements an integer ambiguity resolution algorithm has been developed, which takes advantage of the a priori solution of the EKF to reduce the search space and to provide an on-the-fly solution. The heading-constrained Tightly-Coupled approach followed in this paper has shown superior attitude accuracies when compared to the regular Tightly-Coupled implementation. © 2013 IEEE.

Tahir M.,Polytechnic University of Turin | Presti L.L.,Polytechnic University of Turin | Fantino M.,Navigation Laboratory
International Journal of Navigation and Observation | Year: 2012

The problem of designing robust systems to track global navigation satellite system (GNSS) signals in harsh environments has gained high attention. The classical closed loop architectures, such as phase locked loops, have been used for many years for tracking, but in challenging applications their design procedure becomes intricate. This paper proposes and demonstrates the use of a quasi-open loop architecture to estimate the time varying carrier frequency of GNSS signals. Simulation results show that this scheme provides an additional degree of freedom to the design of the whole architecture. In particular, this additional degree of freedom eases the design of the loop filter in harsh environments. Copyright © 2012 Muhammad Tahir et al.

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