Signal Quality Monitoring for New GNSS Signals

International audienceIn the context of GNSS signals and associated augmentation systems modernization, new modulations are envisaged. More precisely Galileo E1C, the pilot component of the E1 Open Service signal (CBOC(6,1,1/11) modulation), Galileo E5a and GPS L5 (BPSK(10) modulation) are signals that will be used by civil aviation airborne receivers for pseudorange computation. To meet stringent requirements defined for civil aviation GNSS receivers, the characterization of distortions which could affect a GNSS signal in a hazardous way is required. In particular, expected signal distortions generated at payload level are described by Threat Models (TM). Distortions incorporate in the TM are also called Evil Waveform (EWF). These TMs, and their associated parameter ranges, referred to as Threat Space (TS) are powerful and necessary tools to design and test the performance of Signal Quality Monitor (SQM). The SQM is a mean to detect the presence of dangerous signal distortions and is necessary to protect users with high requirements in terms of integrity, accuracy, availability, and continuity (for example civil aviation users). Nowadays, this monitoring task is performed by GBAS and SBAS reference station for GPS L1 C/A to warn the user in a timely manner. In this paper SQMs for Galileo E1C and Galileo E5a will be designed and compared by mean of an innovative representation inspired from [1]. From this representation, SQM performance is assessed based on the highest differential tracking error entailed by a signal distortion included in the TM and not detected by the SQM within allocated Pfa and Pmd.. It is noteworthy that performance of SQM is dependent on several parameters and in particular on the C/N0 at which the reference station is operating. One of the advantage of the proposed representation is that performances of the SQM can be assessed for different equivalent C/N0 from one figure. Using this representation, different SQMs are compared and an optimized SQM is proposed to monitor signal distortions on Galileo E5a and Galileo E1C signals

Signal Quality Monitoring Design for Galileo E5a and Galileo E1C signals

International audienceGalileo E1C, the pilot component of the E1 Open Service signal (CBOC(6,1,1/11) modulation), Galileo E5a and GPS L5 (BPSK(10) modulation) are signals that will be used by civil aviation receivers for pseudorange computation. To meet stringent requirements defined for civil aviation GNSS receivers, the characterization of distortions which could affect a GNSS signal in a hazardous way is required. In particular, expected signal distortions generated at payload level are described by Threat Models (TMs). Distortions incorporated in the TM are also called Evil WaveForm (EWF).These TMs, and their associated parameter ranges, referred to as Threat Space (TS), are powerful and necessary tools to design and test the performance of Signal Quality Monitor (SQM). The SQM is a mean to detect the presence of dangerous signal distortions and is necessary to protect users with high requirements in terms of integrity, accuracy, availability, and continuity (for example civil aviation users). Nowadays, this monitoring task is performed by GBAS and SBAS reference stations for GPS L1 C/A to warn the user in a timely manner. In this paper, SQMs for Galileo E1C and Galileo E5a will be designed and compared using a new representation introduced in [1]. Using this representation, different SQMs are compared and an optimized SQM is proposed to monitor signal distortions on Galileo E5a and Galileo E1C signals

Association of respiratory symptoms and lung function with occupation in the multinational Burden of Obstructive Lung Disease (BOLD) study

Background Chronic obstructive pulmonary disease has been associated with exposures in the workplace. We aimed to assess the association of respiratory symptoms and lung function with occupation in the Burden of Obstructive Lung Disease study. Methods We analysed cross-sectional data from 28 823 adults (≥40 years) in 34 countries. We considered 11 occupations and grouped them by likelihood of exposure to organic dusts, inorganic dusts and fumes. The association of chronic cough, chronic phlegm, wheeze, dyspnoea, forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1)/FVC with occupation was assessed, per study site, using multivariable regression. These estimates were then meta-analysed. Sensitivity analyses explored differences between sexes and gross national income. Results Overall, working in settings with potentially high exposure to dusts or fumes was associated with respiratory symptoms but not lung function differences. The most common occupation was farming. Compared to people not working in any of the 11 considered occupations, those who were farmers for ≥20 years were more likely to have chronic cough (OR 1.52, 95% CI 1.19–1.94), wheeze (OR 1.37, 95% CI 1.16–1.63) and dyspnoea (OR 1.83, 95% CI 1.53–2.20), but not lower FVC (β=0.02 L, 95% CI −0.02–0.06 L) or lower FEV1/FVC (β=0.04%, 95% CI −0.49–0.58%). Some findings differed by sex and gross national income. Conclusion At a population level, the occupational exposures considered in this study do not appear to be major determinants of differences in lung function, although they are associated with more respiratory symptoms. Because not all work settings were included in this study, respiratory surveillance should still be encouraged among high-risk dusty and fume job workers, especially in low- and middle-income countries.publishedVersio

Cohort Profile: Burden of Obstructive Lung Disease (BOLD) study

The Burden of Obstructive Lung Disease (BOLD) study was established to assess the prevalence of chronic airflow obstruction, a key characteristic of chronic obstructive pulmonary disease, and its risk factors in adults (≥40 years) from general populations across the world. The baseline study was conducted between 2003 and 2016, in 41 sites across Africa, Asia, Europe, North America, the Caribbean and Oceania, and collected high-quality pre- and post-bronchodilator spirometry from 28 828 participants. The follow-up study was conducted between 2019 and 2021, in 18 sites across Africa, Asia, Europe and the Caribbean. At baseline, there were in these sites 12 502 participants with high-quality spirometry. A total of 6452 were followed up, with 5936 completing the study core questionnaire. Of these, 4044 also provided high-quality pre- and post-bronchodilator spirometry. On both occasions, the core questionnaire covered information on respiratory symptoms, doctor diagnoses, health care use, medication use and ealth status, as well as potential risk factors. Information on occupation, environmental exposures and diet was also collected

Extension of EWF Threat Model and Associated SQM

International audienc

Signal Quality Monitoring for New GNSS Signals

Version augmentée de la publication de International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2016)International audienceIn the context of GNSS signals and associated augmentation systems modernization, new modulations are envisaged. More precisely Galileo E1C, the pilot component of the E1 Open Service signal (CBOC(6,1,1/11) modulation), Galileo E5a and GPS L5 (BPSK(10) modulation) are signals that will be used by civil aviation airborne receivers for pseudorange computation. To meet stringent requirements defined for civil aviation GNSS receivers, the characterization of distortions which could affect a GNSS signal in a hazardous way is required. In particular, expected signal distortions generated at payload level are described by Threat Models (TM). Distortions incorporate in the TM are also called Evil Waveform (EWF). These TMs, and their associated parameter ranges, referred to as Threat Space (TS) are powerful and necessary tools to design and test the performance of Signal Quality Monitor (SQM). The SQM is a mean to detect the presence of dangerous signal distortions and is necessary to protect users with high requirements in terms of integrity, accuracy, availability, and continuity (for example civil aviation users). Nowadays, this monitoring task is performed by GBAS and SBAS reference station for GPS L1 C/A to warn the user in a timely manner. In this paper SQMs for Galileo E1C and Galileo E5a will be designed and compared by mean of an innovative representation inspired from [1]. From this representation, SQM performance is assessed based on the highest differential tracking error entailed by a signal distortion included in the TM and not detected by the SQM within allocated Pfa and Pmd.. It is noteworthy that performance of SQM is dependent on several parameters and in particular on the C/N0 at which the reference station is operating. One of the advantage of the proposed representation is that performances of the SQM can be assessed for different equivalent C/N0 from one figure. Using this representation, different SQMs are compared and an optimized SQM is proposed to monitor signal distortions on Galileo E5a and Galileo E1C signals

Estimation of GNSS Signals’ Nominal Distortions from Correlation and Chip Domain

International audienceThis paper analyses two ways to investigate nominal distortions of GNSS signals. Firstly, these perturbations can be observed from the correlation function point of view and secondly, from the CDO (Chip domain observable) which is a way to extract the shape of such distortions directly from the digitized signal samples using the code periodicity. This method is also known as the Vision Correlator (NovAtel). [1]These two techniques are compared in terms of capacity to observe and characterize GNSS signal nominal deformations. The CDO has the advantage to process only one specific part of the signal whereas the correlation function observable is less affected by the noise and is directly linked with the pseudorange estimation. As a conclusion, this publication proposes a new way to perform the Signal Quality Monitoring based on the Chip Domain Observable

A Proposal for Multi-Constellation Advanced RAIM for Vertical Guidance

The GNSS environment will experience major changes in the coming years. GPS and GLONASS are undergoing modernization phases, while Galileo and Compass are currently in their deployment phase. When all these constellations are in their Full Operational Capability (FOC) state, there will be at least three times as many ranging sources than today. In addition, all of these GNSS core constellations will broadcast signals in the two frequency bands, L1/E1 and L5/E5. These signals will be available for civil aviation, allowing users to cancel the pseudorange errors due to the ionosphere. Many studies suggest that it could be possible to achieve global coverage of vertical guidance using multi-constellation, dual frequency Advanced Receiver Autonomous Integrity Monitoring (ARAIM). The benefits of ARAIM would include a reduced ground infrastructure (which would reduce the maintenance costs compared to current augmentation systems), a reduced dependency on any one GNSS core constellation, and, in general, lessen exposure to single points of failure. However, to achieve vertical guidance using ARAIM, it will not be sufficient to adapt the RAIM algorithms that are used for horizontal navigation. This is due to the increased level of safety required for vertical guidance compared to horizontal guidance. Therefore, ARAIM will require a careful faults and effects analysis. Because the integrity provision will be shared across service providers, it will be necessary to develop a common understanding in at least three domains: the navigation requirements, starting with LPV- 200; the airborne algorithm; and the threat model, comprised of both the nominal performance of the constellations and the fault modes. In this paper, we present a concept for the provision of integrity using multiple constellations with ARAIM and an Integrity Support Message (ISM). We will first propose an interpretation of the LPV-200 requirements in the ARAIM context. We will then propose a typical threat model for GNSS which includes both the nominal performance of the constellations and all the faults that need to be mitigated. These threats include both single satellite faults, multiple satellite faults, and constellation wide faults, one of them being the use or broadcast of erroneous Earth Orientation Parameters. We will show how the threats can be mitigated through the use of ground monitoring and the ISM in addition to the ARAIM subset position and residual test. Finally, we will give examples of multiple constellation configurations and performance providing worldwide coverage of LPV-200

Do Solid Earth Tides have a local behaviour? First results from the analysis of 20-year GNSS timeseries

This work presents the first results of the project: Tidal Interplate Lithospheric Deformation of Earth (TILDE) funded by ESA under the NAVISP program (NAVISP-EL1-047). The goals of TILDE project are the estimation of Local Solid Earth Tides (LSET); i.e., models which depends on the geographical position of the selected sites. Furthermore it will investigate possible correlations between LSET and geological/geophysical events, such as tectonic plates movements, earthquakes and volcanic activities. Finally, we test if the adoption of LSET modelling can improve the quality of GNSS geodetic solutions. 73 GNSS stations have been selected all over the world for which a stack of data of 20-year long at least were available. We have processed the data providing the solutions (namely coordinates) with a sampling rate in turn of 1 day (1D) and 3 hours (3H). For each solution, we have in turn switched off (OFF) and switched on (ON) the SET. The solutions with sampling rate of 1D and the OFF mode were used to estimate long periodic constituents (LPC) of LSET; while 3H solutions will be used for shorter ones. We will present the first results achieved working on LPC. A relationship has been found between Love and Shida numbers and the absolute values of the latitudes of the GNSS stations to which they refer to. Their relationship is a convex parabola which has the maximum just close to tectonic equator which has an inclination of about 28.5 degrees, corresponding to the ecliptic angle increased by the moon inclination of five degrees

Gaps In using bronchodilators, inhaled corticosteroids and influenza vaccine among 23 high- and low-income sites

Background Increasing access to essential respiratory medicines and influenza vaccination has been a priority for over three decades. Their use remains low in low- and middle-income countries (LMICs), where little is known about factors influencing use, or about the use of influenza vaccination for preventing respiratory exacerbations. Methods We estimated rates of regular use of bronchodilators, inhaled corticosteroids and influenza vaccine, and predictors for use among 19 000 adults in 23 high-income countries (HICs) and LMIC sites. Results Bronchodilators, inhaled corticosteroids and influenza vaccine were used significantly more in HICs than in LMICs, after adjusting for similar clinical needs. Although they are used more commonly by people with symptomatic or severe respiratory disease, the gap between HICs and LMICs is not explained by the prevalence of chronic obstructive pulmonary disease or doctor-diagnosed asthma. Site-specific factors are likely to influence use differently. The gross national income per capita for the country is a strong predictor for use of these treatments, suggesting that economics influence under-treatment. Conclusion We still need a better understanding of determinants for the low use of essential respiratory medicines and influenza vaccine in low-income settings. Identifying and addressing these more systematically could improve the access and use of effective treatments.</p