Simon Banville

Natural Resources Canada | NRCan · Canadian Geodetic Survey

Introducing ionospheric information into a precise point positioning (PPP) solution enables faster ambiguity resolution and significantly improves positioning accuracy. To compute such corrections over wide areas, sparse networks with potentially irregular station distributions are often used. This aspect brings a new level of complexity as ionosph...

The use of global navigation satellite systems (GNSS) precise point positioning (PPP) to estimate zenith tropospheric delay (ZTD) profiles in kinematic vehicular mode in mountainous areas is investigated. Car-mounted multi-constellation GNSS receivers are employed. The Natural Resources Canada Canadian Spatial Reference System PPP (CSRS-PPP) online...

Precise point positioning (PPP) uses precise satellite orbits, clock corrections and biases derived from a global network of reference stations to enable accurate positioning worldwide. Natural Resources Canada's Canadian Spatial Reference System (CSRS) PPP is a free Web service offering automated PPP processing. A critical factor limiting the adop...

The orientation of GNSS satellites in space is a key quantity in GNSS data processing. It is required to correctly apply several force models and observation corrections. Incorrect or insufficient modeling of satellite attitude can lead to inconsistencies both among providers of GNSS products and between providers and users, which negatively affect...

Global navigation satellite system (GNSS) constellations such as GPS, GLONASS, Galileo, and BeiDou and the Japanese regional system QZSS apply various satellite attitude modes during eclipse season, which is the period when the Sun is close to the orbital plane of the satellite. Due to different satellite manufacturers and technological advances ov...

Techniques enabling precise point positioning with ambiguity resolution (PPP-AR) were developed over a decade ago. Several analysis centers of the International GNSS Service (IGS) have implemented such strategies into their software packages and are generating (experimental) PPP-AR products including satellite clock and bias corrections. While the...

The availability of raw observations from smartphones and tablets brings new challenges to GNSS data processing. Low-cost GNSS chipsets, combined with omnidirectional antennas, can lead to measurements highly contaminated by noise and multipath. Therefore, data quality depends not only on the device but also on the environment. Such a diversity is...

The availability of the Galileo E6 signal provides a significant step forward for PPP-AR, permitting instantaneous convergence. As a result of frequency separation, unambiguous widelane signals have low noise characteristics, which further benefits the resolution of the whole set of ambiguities. The strategy used in our study is a generalization of...

GLONASS ambiguity resolution in differential real-time kinematic (RTK) processing is affected by inter-frequency phase biases (IFPBs). Previous studies empirically determined that IFPBs are linearly dependent on the frequency channel number and calibration values have been derived to mitigate these biases for geodetic receivers. The corresponding I...

Higher-order ionospheric effects, if not properly accounted for, can propagate into geodetic parameter estimates. For this reason, several investigations have led to the development and refinement of formulas for the correction of second- and third-order ionospheric errors, bending effects and total electron content variations due to excess path le...

We revisit the geometric interpretation of GPS dilution of precision (DOP) factors giving emphasis on the geometric impact of the receiver clock parameter on the conventional GPS positioning solution. The comparison is made between the solutions with and without an estimated receiver clock parameter, i.e., conventional GPS versus pure trilateration...

A collaboration between CNES and NRCan to write a real-time GNSS clock combination software preserving the integer nature of the carrier-phase ambiguities at the user end.

Results from a zero-length baseline calibration site operated by NRCan, where the interoperability of 5 receiver types (Septentrio, NovAtel, Trimble, Topcon and Javad) has been analyzed.

It is well known that the attitude of GNSS satellites during eclipse seasons suffers from inexact or deficient modeling. The consequences of these errors are limited but there is some impact on the measurement residuals and this partly affects the orbit quality of eclipsing satellites. In addition, it is important to have consistent models between...

Earth surface deformations are commonly studied by processing observations of continuously operating GPS (CGPS) stations located in the deformation area using differential methods. In this study, we assessed the performance of precise point positioning (PPP) with and without ambiguity resolution (AR) to recover station velocities. Using 37 CGPS sta...

During its “I/O 2016” conference held in May 2016, Google announced that raw GNSS measurements from smartphones and tablets running the Android N (“Nougat” = version 7) operating system would be made available to developers. The implications of this initiative are significant for the community since it allows us to move away from the black-box conc...

While satellite clock combinations are routinely utilized within the IGS, they currently disregard the fact that some ACs provide integer clocks. Users have been expected to choose either a robust combined solution or select individual AC solutions that provide integer clocks allowing the user to compute a PPP-AR solution. The goal of our investiga...

Current GLONASS satellites transmit signals based on the frequency division multiple access (FDMA) technology. Due to equipment delays occurring within GNSS receivers, GLONASS carrier-phase and code observations are contaminated by inter-frequency biases. As a consequence, GLONASS ambiguity parameters in long-baseline processing are typically estim...

The integration of GLONASS data into GNSS-derived total electron content (TEC) products involves the estimation of a large number of parameters to model inter-frequency code biases. This issue can be avoided by using undifferenced integer ambiguities obtained from geodetic processing software to remove the arc-dependency of geometry-free carrier-ph...

Ionospheric models have become useful tools for both improving the accuracies of positioning and navigation and scientific research. The data-driven modelling techniques have been proven to be good candidates for real-time applications due to their ease of use and potentially higher accuracy compared to broadcast models. In this paper, we propose t...

The convergence period associated with precise point positioning (PPP) is often a limiting factor for the adoption of this technique in applications requiring short on-site occupation times. Centimeter-level accuracies can be obtained much faster from PPP when external information on the ionosphere is provided from nearby reference stations. This s...

The precise point positioning (PPP) methodology allows for cm-level positioning accuracies using a single GNSS receiver, through careful modelling of all error sources affecting the signals. Adoption of PPP in several applications is however muted due to the time required for solutions to converge or re-converge to their expected accuracy, which re...

Rapid convergence of precise point positioning (PPP) solutions to cm-level precision is a key factor for many applications. One means of accelerating this convergence is to exploit the benefit of information on the ionosphere. In order to preserve the integer nature of carrier-phase ambiguities in PPP, it is imperative that ionospheric corrections...

Ionospheric modeling plays an important role in improving the accuracies of positioning and navigation, especially for current civil aircraft navigation and mass-market single-frequency users. Measurement-driven models are considered to be among the best candidates for real-time single-frequency positioning owing to their real-time applicability an...

To achieve undifferenced GLONASS ambiguity resolution, it is imperative to adequately model both inter-frequency carrier-phase and code biases. This paper demonstrates that the apparent linear frequency response associated with carrier phases can be rigorously modeled by selecting two reference satellites with adjacent frequency channels. This cond...

GLONASS processing from mixed receiver types is typically subject to unmodeled inter-frequency phase biases which prevent carrier phase ambiguity parameters from converging to integers. Receiver-dependent values have been proposed to mitigate the contribution of these biases, but are still subject to a number of issues, such as firmware updates. Re...

The global navigation satellite systems (GNSS) are an important component of ionosphere monitoring, since signals travelling from satellites to ground-based receivers allow sampling of the total electron content (TEC) at a multitude of locations simultaneously. Due to the ambiguous nature of the precise carrier-phase observables, it is common pract...

With external corrections from a network of stations, cm-level positioning can now be achieved with single-frequency receivers. Since processing of carrier-phase data might be affected by a convergence period due to the estimation of ambiguity parameters, quick recovery from tracking interruptions is critical in maintaining a continuous precise nav...

The GIOVE test-bed satellites were orbited to secure the use of the frequencies allocated by the International Telecommunication Union for the Galileo system. Dual-frequency measurements from the GIOVE satellites and triple frequency measurements from the IOV satellites have been archived by a number of continuously operating receivers including th...

Processing of data from global navigation satellite systems (GNSS), such as GPS, GLONASS and Galileo, can be considerably impeded by disturbances in the ionosphere. Cycle-slip detection and correction thus becomes a crucial component of robust software. Still, dealing with ionospheric cycle slips is not trivial due to scintillation effects in both...

The determination of slant total electron content (STEC) between GPS satellites and receivers usually implies a "levelling" procedure in which the precise but ambiguous carrier-phase measurements are fitted to the noisy code measurements. It is now recognized that arc-dependent biases, caused by code multipath and inter-frequency bias fluctuations,...

During disturbed ionospheric conditions such as the occurrence of plasma bubbles, the phase and amplitude of the electromagnetic waves transmitted by GPS satellites undergo rapid fluctuations called scintillation. When this phenomenon is observed, GPS receivers are more prone to signal tracking interruptions, which prevent continuous measurement of...

Real-time precise point positioning (PPP) is limited to only a few applications using a moving receiver, because the quality of the solution is vulnerable to interruptions in signal tracking. A loss of lock on all GPS signals simultaneously even implies that users may have to wait for several minutes before again obtaining cm-level precision. To av...

In an attempt to clearly understand the impacts of antenna rotation on the performance of kinematic precise point positioning (PPP), this paper examines how unmodelled receiver antenna carrier-phase wind-up and antenna phase-centre variations (PCV) could propagate in PPP solutions. The major concern with antenna rotation and PPP lies in the definit...

Nowadays, still few people use precise point positioning (PPP) to process GPS data from a moving receiver because the quality of the solution is extremely vulnerable to interruptions in signal tracking. A loss of lock on all GPS signals simultaneously implies that users may have to wait for several minutes (even hours in certain cases) before obtai...

Precise point positioning (PPP), considered an alternative to differential positioning, is used in a significantly increased number of applications. Its integration into many practical areas is, however, slowed down by the long convergence time required in order to obtain cm-level accuracy. This drawback is caused by the difficulty in fixing carrie...