Through a series of four vehicle experiments leveraging low-cost GNSS/IMU sensors, the findings from this research indicate that low-cost HAS PPP solutions can yield results comparable to those obtained using CNES ultra-rapid products at the 68th percentile of errors.

DING YI AND SUNIL BISNATH YORK UNIVERSITY, CANADA

NACER NACIRI JPL, USA

F. JAVIER DE BLAS EUSPA, EUROPEAN UNION

ROBERTO CAPUA SOGEI SPA, ITALY

In January 2023, EUSPA officially announced the Galileo High Accuracy Service (HAS) reached initial service through the E6B signal [1]. With the availability of HAS data, users worldwide can retrieve precise GPS+Galileo orbit and clock corrections, as well as satellite code biases in real-time and for free with 24/7 operated service delivery and committed performance levels. This trend has further boosted the development of GNSS receivers and mass-market applications, such as Intelligent Transportation Systems (ITS), precise agriculture and mobile mapping [2]. While there has been a growing interest in assessing the performance of Galileo HAS in Precise Point Positioning (PPP) processing mode for civil applications, there has yet to be an investigation into the use of low-cost sensor data with HAS corrections in urban driving environments. The objective of this study is to evaluate the performance of Galileo HAS PPP in real-world driving conditions using low-cost GNSS and IMU sensors.

Rapid technological advancement

In the pursuit of accurate positioning, two advanced satellite positioning techniques have gained widespread adoption in mass-market applications: PPP and Real-Time Kinematic (RTK). Unlike RTK, which relies on Observation Space Representation (OSR) messages, PPP uses State Space Representation (SSR) data to achieve performance similar to RTK [3,4]. For this study, these SSR messages are sourced from the International GNSS Service (IGS) Analysis Centers (ACs), which provide precise satellite orbit and clock products. Additionally, the IGS has introduced Real-Time Service (RTS) to disseminate SSR corrections, which are provided in the RTCM-3 format and can be accessed through Networked Transport of RTCM via Internet Protocol (NTRIP). PPP, compared to RTK, demands a longer time to achieve centimeter-level accuracy due to its inability to eliminate certain GNSS errors, such as receiver clock errors and atmospheric delays. However, PPP offers distinct advantages, notably the absence of the establishment of local reference stations and the ability to provide continuous, high-quality Positioning, Navigation and Timing (PNT) services without being limited by baseline length.

Instead of broadcasting corrections through the Internet, a recent development in positioning communities has witnessed the emergence of the direct broadcast of SSR corrections via GNSS constellations. As a pioneer in providing GNSS augmentation services, Japan’s Quasi-Zenith Satellite System Centimeter-Level Augmentation Service (QZSS CLAS) is notable for being the first augmentation system to transmit Compact SSR (CSSR) corrections through the L6D signal in 2020, aiming to provide satellite orbit, clock, code/phase biases, and ionospheric/tropospheric corrections to GPS, Galileo and QZSS satellites across Japan [5,6]. To extend the service area for the entire Asia-Oceania region, the Japan Aerospace Exploration Agency (JAXA) introduced the Multi-GNSS Advanced Orbit and Clock Augmentation (MADOCA) system. In 2022, MADOCA initiated its PPP trail service to disseminate satellite orbit, clock, code/phase corrections for GPS, Galileo, GLONASS, BDS and QZSS satellites through the L6E signal [7]. Similarly, BDS-3 (BeiDou-3) offers customized CSSR corrections, including GPS + BDS satellite orbit/clock corrections and code biases through the B2b signal, all geared toward achieving high PPP performance for users in China and the surrounding regions [8,9]. More recently, an open Python toolkit CSSRlib has been created to leverage SSR corrections from multiple free services, allowing for a straightforward comparison and use of different augmented PPP services [10]. 

In contrast to regional services, the European Union is actively progressing in the development of the Galileo High Accuracy Service (HAS). Galileo HAS is expected to play a pioneering role by offering free Signal-in-Space (SIS) corrections to users worldwide. Unlike other PPP services that rely on denser reference station networks, current HAS corrections are generated by 15 Galileo Sensors Stations (GSS) and related infrastructure, and they are broadcasted within the Galileo C/NAV navigation message through the E6B signal at 1278.75 MHz [11]. As of January 2023, Galileo HAS initial service has been declared operational, and these corrections have been accessible both through Galileo E6-B signals and HAS Internet Data Distribution (IDD) service [1]. 

The official announcement of operational deployment of the Galileo HAS initial service has sparked significant interest in the global navigation and positioning community for exploring the potential applications of HAS PPP in civil applications. In early trials, several studies investigated HAS corrections accuracy through signal-in-space range error (SISRE) and differential code bias (DCB) differences [12, 13]. More recently, [14] provides insight into the capabilities of live HAS test signals in 2022. It was observed that these signals could deliver Galileo and GPS orbit and clock corrections with SISRE values of 10.6 cm and 11.8 cm, respectively. [14, 15] also demonstrated that GPS+Galileo HAS PPP solutions can provide real-time 95th percentile positioning performance (2-sigma) of better than 20 cm and 40 cm for cadastral surveying in the horizontal and vertical domains, respectively. Meanwhile, the maturity of GNSS and its associated augmentation services has catalyzed unprecedented growth and evolution of low-cost, multi-frequency, multi-constellation GNSS receivers and antennas. 

This surge in technological advancement has given rise to cost-effective GNSS/IMU sensor integration, which has received considerable attention within the Location-Based Services (LBS) communities [16, 17, 18]. Although progress has been made, there has been no publications of quantitative investigations of low-cost sensors HAS solutions in realistic driving scenarios. Therefore, the main contributions and novelties of this study are to answer the following questions: 1) Compared to the analysis in 2022, how do recent HAS corrections perform in terms of data availability, SISRE and DCB differences? 2) Regarding PPP performance in real-world driving environments, how comparable are HAS broadcasted corrections to CNES ultra-rapid products? 3) With the inclusion of low-cost IMU measurements, how do HAS low-cost tightly-coupled GNSS/IMU integrated solutions behave under different driving conditions?

To address the proposed questions, this article first describes the HAS corrections and the processing methodology for the HAS PPP engine. The next section depicts the experimental setup and assesses the HAS corrections in July 2023, followed by corresponding positioning performance and analysis. 

HAS Corrections Description 

Aligned with the targets proposed by the European Commission (EC), Galileo HAS Service Level 1 (SL1) has a primary goal of providing global GPS + Galileo satellite orbit, clock and biases corrections, conveyed at a data rate of 448 bits per second and structured in a format similar to CSSR. The aim is to facilitate PPP-based horizontal and vertical accuracies better than 20 cm and 40 cm, respectively, with a convergence time of 300 seconds and 99% data availability. Furthermore, Galileo HAS Service Level 2 (SL2) is designed to extend the offerings by providing atmospheric corrections to users within the European Coverage Area (ECA). This expansion makes so-called “PPP-RTK” feasible, potentially reducing the convergence time to less than 100 seconds. The full operational deployment of Galileo HAS is scheduled for the coming two to three years, promising further advancements in satellite-based positioning accuracy and capabilities [2].

As outlined in the Galileo HAS information note, the implementation of Galileo HAS is organized into three phases, as depicted in Figure 1 [2]. Phase 0 involved the successful completion of HA testing and experimentation activities between 2019 and 2022, validating Galileo’s dissemination capabilities. Phase 1, referred to as HA Initial Service, was designed to provide an SL1 service with reduced performance. This phase officially began in January 2023. HAS implementation will then advance to Phase 2, achieving full implementation of Galileo HAS and meeting performance objectives of SL1 and SL2. Current improvements being focused on include additional reference stations and the introduction of Galileo and GPS satellite phase bias corrections, which will allow for faster and more accurate PPP-AR (PPP with carrier-phase ambiguity resolution) on the part of users.

According to the Galileo HAS Interface Control Document (ICD) [19] the constituent elements of HAS corrections involve 1) Satellite orbit corrections to the broadcast ephemerides; 2) Satellite clock corrections to the broadcast ephemerides; 3) Satellite biases. It’s important to note that, as of the information available in the ICD, satellite phase biases are still under development and are not accessible to users at this time. The HAS user reference algorithm (that will be made available for free to any interested party), will ease the accessibility to this service worldwide.

HAS Orbit Corrections

The HAS service provides orbit corrections for GPS and Galileo satellites in the Satellite Coordinate System (SCS), comprising radial, along-track, and cross-track (RAC) components. These corrections are associated with the ionosphere-free antenna phase center (APC) of the satellite, specifically for GPS LNAV and Galileo I/NAV messages.

In general, HAS orbit corrections cover a range of ±10.2375 m, ±16.376 m, and ±16.376 m for the respective RAC directions, with updates occurring at 50-second intervals and a validity period of 300 seconds. Equation 1 illustrates the relationship between the HAS corrected satellite positions  and corresponding corrections δR^s.

where x_s denotes the broadcast satellite position, and  stands for the rotation matrix employed to transform the corrections from the RAC system into the designated Earth-Centered Earth-Fixed (ECEF) frame. As post-processing products from ACs are based on the center of mass (CoM), there is a viable option to convert the APC-based HAS orbits to CoM-based orbits by applying the ionospheric-free phase centre offsets (PCO) corrections sourced from the supplementary ANTEX files:

HAS Clock Corrections

As with the HAS orbit corrections, HAS clock corrections refer to the ionospheric-free combination of the GPS LNAV signals (L1 C/A and L2P) and Galileo I/NAV signals (E1 and E5b). For each satellite, the HAS corrections denoted as δC^s, are computed from the Delta Clock Correction (DCC) and Delta Clock Multiplier (DCM), falling within a range of ±40.95 m, with a 10-second update interval and a 60-second validity period. Prior to being incorporated into the ionospheric-free broadcast navigation clock errors dt^s, it’s essential to consider the relativistic correction  for Galileo satellites. Equation 3 depicts the expression for HAS clock errors:

where  and dt^s are the corrected clock error and broadcast clock error for Galileo satellites, and c is the speed of light.

HAS Satellite Code Biases

Aside from orbit and clock corrections, HAS encompasses support for satellite code biases corrections that are applied to GPS on L1 C/A, L2C, and L2P signals and Galileo on E1 C, E5A Q, and E5B Q signals. Unlike the satellite Differential Signal Bias (DSB) products, HAS code biases are disseminated in the format of Observable-specific Signal Biases (OSBs). These code corrections are framed as pseudo-absolute biases, enabling the direct application to the corresponding pseudorange measurements for users. The range of these biases spans ±20.46 m, with a 50-second update interval and a 60-minute validity period. An example of the conversion between DSB and OSB corrections is shown as:

where  are the DSB of the Galileo C1C and C5Q code observations, while  and  are the OSB of the Galileo C1C and C5Q, respectively.

Methodology and Processing Architecture

This section begins with the basic mathematical methodologies used for the PPP/IMU tightly-coupled integration, followed by the processing architecture of the York University HAS PPP processing engine.

PPP and Tightly-Coupled Methodology

The dual-frequency observations from both GPS (L1/L2) and Galileo (E1/E5b) signals are employed for PPP processing, and the uncombined PPP (UPPP) model is expressed as:

where the pseudorange and carrier-phase measurements on frequency i (i∈{1,2}) are denoted as P and Φ, respectively;  is the geometric range between satellite s and receiver r; dt_r and dt^s represent the receiver and satellite clock offset, and c is the speed of light; f_i refers to the signal frequency on i, and I and T stand for slant ionospheric delay and slant tropospheric delay, respectively; b_P and b_Φ are the code and phase biases, respectively. N is the unknown ambiguity in cycles and λ is the carrier wavelength; ε_P and ε_Φ are pseudorange and phase noise, respectively. In the HAS PPP processing, satellite clock offset (dt^s) and satellite code biases () are provided by HAS corrections.

Incorporating IMU sensor integration, this research uses the tightly-coupled method that integrates the GNSS pseudorange and carrier- phase raw measurements together with IMU measurements into the extended Kalman filter. After iterations and passing the sanity check, the variables from GNSS and IMU can be estimated as:

where δR_x,y,z and δV_x,y,z denote the position and velocity errors in ECEF coordinate system, respectively; δT_r^s stands for the zenith tropospheric delay, which is converted into slant delay with corresponding mapping function. δA_x,y,z refers to the attitude errors in the local navigation system, and b_ax,ay,az and b_gx,gy,gz are the accelerometer and gyroscope biases, respectively.

York HAS Processing Engine 

Figure 2 depicts the processing architecture for the York HAS engine. The HAS corrections and broadcast ephemeris are initially introduced and processed in the Correction Handler module of the code. Subsequently, the calculated HAS orbit, clock and code OSB corrections are directed to the GNSS Handler module. After applying the HAS corrections, the GNSS handler and IMU Handlers acquire and synchronize the raw measurements. The IMU Handler is responsible for aligning IMU raw measurements, initialization and compensating for biases estimated from the previous epoch. Subsequently, the predicted states encompassing attitude, positioning and velocity are conveyed to the TC (tightly-coupled) Handler module. In conjunction with the GNSS measurements, the TC handler undertakes the integration of GNSS and IMU data through the Extended Kalman filter processing engine, with the objective of estimating the unbiased states as shown in Equation 6. Following the quality control and sanity assessments, the York HAS engine advances to the subsequent epoch for processing.

Experimental Setup and HAS Assessment

To investigate the HAS corrections and our proposed algorithms, multiple vehicle experiments were carried out in realistic driving environments. This section introduces the corresponding experimental setup and HAS assessment. 

Measurement Campaign 

To evaluate the effectiveness of HAS corrections and the performance of the York PPP engine, a series of vehicular experiments were conducted in the vicinity of York University, Toronto, Canada. The experimental configuration, depicted in Figure 3, consists of two data collection setups: 1) The geodetic collection employs a NovAtel SPAN (comprising an OEM7 GNSS receiver and Epson IMU) integrated with a NovAtel antenna. 2) The low-cost collection equipment comprises a Septentrio Mosaic-X5 receiver paired with a Tallysman patch antenna. Furthermore, an automotive-grade Xsens MTi-7 IMU is affixed on top of the experiment vehicle. The HAS log files, decoded by NovAtel, are used as input data for the York PPP engine to generate HAS PPP/TC solutions. Additionally, a base station using a NovAtel OEM7 receiver and a geodetic-grade antenna is mounted on an open rooftop within a 5 km baseline length to provide the reference trajectory processed by the NovAtel Inertial Explorer software.

To simulate daily driving environments, four kinematic tests were conducted on different days with a similar route and different multipath profiles. Table 1 highlights the corresponding details of the four vehicle experiments, including test identifiers, collection dates, UTC timestamps, and traffic conditions. Note the traffic conditions fluctuated at different local times, primarily due to variations in traffic volume and traffic density.

Figure 4 shows an aerial street view of the vehicle experiment, which includes multiple multipath profiles like open-sky parking lots, vegetation roads, suburban roads, as well as overpasses. It is anticipated that the GNSS-only positioning solution would experience a significant degradation when the vehicle passes under an overpass due to the limited number of observations. This signal block is the rationale for integrating a low-cost IMU into the navigation solution to enhance robustness and overall positioning performance.

Assessment of HAS Corrections

To evaluate the HAS corrections, a comparative analysis is performed across various criteria, including data availability, Signal-in-Space Range Error (SISRE) and DCB differences. The decoded ASCII HAS files used in this study were provided by Hexagon | NovAtel, a member of the GISCAD- OV project team (giscad-ov.eu).

Data Availability

The results presented focus on the assessment of HAS corrections data availability over a one-week period, from July 22 to July 29, 2023. Considering the HAS orbit and clock corrections are provided with distinct timestamps, their availability is initially examined separately. As shown in Figure 5, green regions denote the presence of corrections accessible to users, while red dots represent instances where HAS corrections were unavailable during those time intervals. Note these results exclusively account for the existence of corrections, without taking into account their validity periods. Both Galileo and GPS exhibit a high degree of HAS orbit availability, with Galileo achieving close to 100% availability, and GPS at ~98%. In contrast, HAS clock availability is somewhat lower, with Galileo achieving 99% availability and GPS satellites attaining 92% availability.

Both orbit and clock corrections are integral components of PPP processing, so it is important to consider them not only in terms of data availability, but also in regard to their respective validity periods. Figure 6 illustrates satellite-specific data availability, and the analysis reveals that, on average, Galileo and GPS satellites can achieve data availability rates of 99% and 92%, respectively. These figures represent an improvement over last year’s performance, where Galileo attained 97% availability, and GPS achieved 91% [14].

Orbit and Clock SISRE Analysis

In the SISRE analysis, a direct comparison is conducted between HAS orbit and clock corrections and the final orbit and clock products provided by the Center for Orbit Determination in Europe (CODE), recognized for its high-quality products. And the detailed SISRE computation equations can be referred to in paper by [20]. Similar to the data availability analysis, the datasets gathered from July 22 to July 29, 2023, are analyzed. Figure 7 shows the SISRE results for HAS orbit 3D and clock corrections specifically on July 22. GPS and Galileo satellites are represented in blue and green dots, respectively.

Figure 8 presents an overview of the average orbital SISRE (represented in green) and total SISRE (represented in purple) for both Galileo and GPS satellites over one week. Owing to unexpected larger errors, G07, G09 and E33 satellites have been excluded from the computation and deserve further investigation. Additionally, Table 2 highlights the overall statistics, indicating HAS is capable of providing orbital and clock corrections with SISRE values of approximately 11 cm and 16 cm, respectively. These accuracy levels are consistent with those observed in 2022 [14]. 

OSB Analysis

In addition to orbit and clock corrections, HAS also provides support for satellite code bias corrections, which are applied to GPS on L1 C/A, L2C, and L2P signals, as well as to Galileo on E1 C, E5A Q, and E5B Q signals. Currently, HAS phase biases are not available to users, so the assessment of PPP-AR (PPP with carrier-phase ambiguity resolution) must wait as future work. To assess the accuracy of HAS OSBs, DCB products from the Chinese Academy of Sciences (CAS) are employed as a reference. Figure 9 and Table 3 indicate the differences in DCB 
between HAS and CAS products are at the sub-nanosecond level. This analysis aligns with the previous conclusion that HAS OSB accuracy remains consistent with the levels observed in 2022 [14]. 

Positioning Results and Analysis

SPP Solutions 

To investigate positioning performance in real-world driving conditions using low-cost sensors, two different GNSS configurations namely SPP (single point positioning) and HAS PPP are initially compared. This comparison is based on the dataset collected on July 25, 2023. SPP represents a traditional GNSS positioning technique frequently employed with low-cost GNSS receivers that are only capable of receiving GNSS pseudorange observations. Figure 10a displays the time series of horizontal errors generated by SPP and HAS PPP. These errors are represented by the red and green lines, respectively. Figures 10b and 10c show the corresponding time series for the number of processed satellites and observations. The observations reveal SPP has the capacity to process a larger number of satellites as compared to HAS PPP. This result is primarily due to the limited availability of HAS corrections. However, despite having access to fewer satellites, HAS PPP consistently delivers more accurate and stable positioning solutions overall when compared to SPP solutions. The improvement is particularly notable when considering metrics such as the 95th percentile errors, 68th percentile errors, and overall rms, as outlined in Table 4. This enhanced performance is attributed to the inclusion of precise carrier phase measurements in the HAS PPP method.

It is worth noting that SPP solutions may, at times, exhibit superior accuracy compared to HAS PPP. This idiosyncrasy occurs when SPP processes a greater number of satellites, leading to more favorable Geometric Dilution of Precision (GDOP), as demonstrated in Figure 10d. Consequently, the effective use of additional satellites and the enhancement of DOP values in HAS PPP solutions deserve further investigation. Additionally, the performance of GNSS-only solutions degrades significantly at certain epochs when the vehicle was traversing an arterial road located beneath a highway viaduct—a notably challenging environment extending over 100 meters.

Positioning Performance Comparison with HAS and CNES Products

A comparative analysis was conducted between HAS corrections and the ultra-rapid products provided by CNES. To ensure an equitable comparison, the DCB values provided by CAS are also taken into consideration when processing CNES PPP solutions, and the satellite orbit, clock and code bias corrections are applied for both GPS and Galileo constellations and processed in the same dual-frequency uncombined mode. Float solutions were examined as HAS satellite phase biases are currently not transmitted to users. Figure 11 presents the time series of low-cost PPP horizontal errors for datasets 1 to 4. The PPP solutions generated by CNES and HAS products are illustrated by blue and green lines, respectively. The red dashed line indicates the convergence threshold. Defining a precise convergence threshold in dynamic environments with frequent signal loss and filter initialization can be challenging, so a more lenient convergence threshold of 50 cm was set.

Table 5 presents a comprehensive analysis of the 95th percentile errors, 68th percentile errors, overall rms, and standard deviation for CNES (left) and HAS (right) PPP solutions throughout the datasets. CNES PPP solutions show superior accuracy and stability compared to HAS PPP solutions, primarily due to the higher availability of satellites in CNES corrections. When focusing on the 68th percentile horizontal performance, where an adequate number of satellites are available for GNSS processing, HAS PPP provides comparable positioning performance to CNES ultra-rapid PPP solutions. CNES PPP solutions generally have better performance than HAS PPP, but the results show the potential of HAS corrections in mass-market applications requiring precise navigation.

Positioning Performance Enhancement with IMU Integration

To mitigate potential positioning errors resulting from GNSS outages, we have tightly-integrated a low-cost IMU with the PPP configuration. Figures 12 and 13 present the time series of positioning errors obtained from the CNES (depicted in blue) and HAS (depicted in green) corrections, with their TC solutions shown in orange lines. It is evident the integration of the IMU leads to a substantial reduction in GNSS outage-related errors across the tested datasets. For dataset 1, which serves as an illustrative case, significant levels of 67% and 75% improvements of overall rms can be observed for CNES and HAS PPP solutions, highlighting the significant advantages of IMU integration.

Figure 14 offers a comprehensive overview of horizontal positioning errors across four datasets, encompassing four combinations of processing strategies. CNES and HAS PPP solutions are represented by blue and green bars, respectively, while their TC solutions are depicted in lighter shades. Several significant conclusions can be drawn from this analysis: 

1) As expected, CNES PPP solutions exhibit superior performance compared to HAS PPP solutions. Specifically, CNES PPP achieves 0.8 m and 0.6 m for the 95th percentile errors and overall rms, respectively, outperforming HAS PPP solutions, which achieve 1.1 m for the 95th percentile errors and 0.7 m for overall rms. However, when focusing on the 68th percentile errors, HAS PPP solutions exhibit comparable positioning performance to CNES products. 2) The TC integration demonstrates little enhancement for 68th percentile positioning, suggesting the inclusion of the IMU does not significantly impact GNSS-only solutions when a sufficient number of observed satellites is available. 3) It is noteworthy that both HAS and CNES TC solutions achieve a horizontal positioning rms of 0.5 m. This indicates the integration of a low-cost IMU effectively narrows the performance discrepancy between using HAS and CNES products, which is likely attributed to limited HAS availability, where IMU mechanization solutions play a more substantial role in determining the final positioning.

Conclusions and Future Work 

To investigate the PPP performance of HAS corrections with low-cost sensors in real-world driving environments, four vehicle experiments were conducted close to York University. The final results provide insights into addressing the posed questions:

Compared to the analysis conducted in 2022, this current study reveals an improvement in data availability. On average, the data indicates that Galileo corrections exhibit an availability rate of 99%, while GPS corrections demonstrate an availability rate of 92% during the period from July 22 to July 29, 2023. However, the SISRE and DCB differences results do not show any significant improvements regarding the accuracy of HAS corrections.

In the context of PPP performance within real-world driving environments, it is evident that CNES PPP solutions consistently outperform HAS PPP solutions when considering metrics such as 95th percentile errors, overall rms and standard deviations. However, an interesting and noteworthy finding is HAS PPP solutions demonstrate comparable, and in some cases, superior performance in terms of the 68th percentile errors. This observation highlights the significant potential of HAS corrections in Location-Based Services (LBS) applications where precise positioning is crucial.

The inclusion of the low-cost IMU leads to several important insights. First, the TC solutions do no harm to GNSS-only solutions when a sufficient number of satellites are available. Furthermore, TC solutions play a pivotal role in significantly mitigating positioning errors during GNSS outages, enhancing the robustness of positioning systems in challenging environments. Most notably, the integration of TC solutions effectively narrows the performance gap between using HAS and CNES corrections, leading to a remarkable achievement of 0.5 m rms for horizontal positioning performance, even in challenging environments. 

For future work, the analysis will be expanded to include PPP ambiguity resolution by incorporating HAS phase bias corrections when they become available. Additionally, it is anticipated that PPP-RTK will become a feasible option within the European coverage area once HAS Phase 2 is fully implemented. Furthermore, improvements to the HAS DOP will be made through Galileo broadcast navigation messages, and these HAS studies will be extended to smartphone applications. These improvements open exciting possibilities for enhancing location-based services and navigation capabilities on widely accessible mobile devices. 

Acknowledgements

The authors would like to thank the EU Horizon 2020 project GISCAD-OV (Grant Agreement 870231) and the Natural Science and Engineering Research Council of Canada for providing funding for this work. And the authors would like to thank the data contribution from the IGS and Hexagon | NovAtel (decoding HAS corrections) and acknowledge the collaboration from Sogei. Finally, the York authors would like to thank their colleagues at the GNSS Laboratory for their support in collecting field data.

This article is based on material presented in a technical paper at ION GNSS+ 2023, available at ion.org/publications/order-publications.cfm. 

References 

[1] EUSPA (2023). Galileo High Accuracy Service goes Live! EU Agency for the Space Programme. https://www.euspa.europa. eu/newsroom/news/galileo-high-accuracy-service-now-operational.

[2] EUSPA (2020). Galileo high accuracy service (HAS) info note. European GNSS Agency. https://www.gsc-europa.eu/sites/ default/files/sites/all/files/Galileo_HAS_Info_Note.pdf.

[3] Zumberge, J., Heflin, M., Jefferson, D., Watkins, M., and Webb, F. (1997). Precise point positioning for the efficient and robust analysis of GPS data from large networks. Journal of geophysical research: solid earth, 102(B3):5005–5017.

[4] Bisnath, S. and Gao, Y. (2009). Current state of precise point positioning and future prospects and limitations. In Observing our changing earth, pages 615–623. Springer.

[5] Saito, M., Sato, Y., Miya, M., Shima, M., Omura, Y., Takiguchi, J., and Asari, K. (2011). Centimeter-class augmentation system utilizing quasi-zenith satellite. In Proceedings of the 24th International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GNSS 2011), pages 1243–1253.

[6] Miya, M., Fujita, S., Sato, Y., Ota, K., Hirokawa, R., and Takiguchi, J. (2016). Centimeter level augmentation service (CLAS) in Japanese quasi-zenith satellite system, its user interface, detailed design, and plan. In Proceedings of the 29th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2016), pages 2864–2869.

[7] Kawate, K., Igarashi, Y., Yamada, H., Akiyama, K., Okeya, M., Takiguchi, H., Murata, M., Sasaki, T., Matsushita, S., Miyoshi, S., et al. (2023). MADOCA: Japanese precise orbit and clock determination tool for GNSS. Advances in Space Research, 71(10):3927–3950.

[8] Tao, J., Liu, J., Hu, Z., Zhao, Q., Chen, G., and Ju, B. (2021). Initial Assessment of the BDS-3 PPP-B2b RTS compared with the CNES RTS. GPS Solutions, 25:1–16.

[9] Xu, Y., Yang, Y., and Li, J. (2021). Performance evaluation of bds-3 ppp-b2b precise point positioning service. GPS Solutions, 25(4):142.

[10] Hirokawa, R., Hauschild, A., & Everett, T. (2023, September). Python Toolkit for Open PPP/PPP-RTK Services. In Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023) (pp. 2514-2526).

[11] de Blas, F. J., Vázquez, J., Hernández, C., Ostolaza, J., Lagrasta, S., Fernandez-Hernández, I., & Blonski, D. (2023, September). The Galileo High Accuracy Service (HAS): A Pioneer Free-of-Charge Global Precise Positioning Service. In Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023) (pp. 449-468).

[12] Hauschild, A., Montenbruck, O., Steigenberger, P., Martini, I., and Fernandez-Hernandez, I. (2022). Orbit determination of Sentinel-6A using the Galileo high accuracy service test signal. GPS Solutions, 26(4):120.

[13] Fernandez-Hernandez, I., Chamorro-Moreno, A., Cancela-Diaz, S., Calle-Calle, J. D., Zoccarato, P., Blonski, D., Senni, T.,  de Blas, F. J., Hernández, C., Simón, J., et al. (2022). Galileo high accuracy service: initial definition and performance. GPS Solutions, 26(3):65.

[14] Naciri, N., Yi, D., Bisnath, S., de Blas, F. J., and Capua, R. (2023). Assessment of Galileo High Accuracy Service (HAS) test signals and preliminary positioning performance. GPS Solutions, 27(2):73.

[15] Naciri, N., Yi, D., Bisnath, S., de Blas, F. J., and Capua, R. (2022). Validation of a European High accuracy GNSS service for cadastral surveying applications. In Proceedings of the 35th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2022), pages 381–396.

[16] Abd Rabbou, M. and El-Rabbany, A. (2015). Tightly coupled integration of GPS precise point positioning and MEMS-based inertial systems. GPS Solutions, 19:601–609.

[17] Vana, S. and Bisnath, S. (2020). Enhancing navigation in difficult environments with low-cost, dual-frequency GNSS PPP and MEMS IMU. In Beyond 100: The Next Century in Geodesy: Proceedings of the IAG General Assembly, Montreal, Canada, July 8-18, 2019, pages 143–150. Springer.

[18] Yi, D., Yang, S., and Bisnath, S. (2022). Native smartphone single-and dual-frequency GNSS-PPP/IMU solution in real-world driving scenarios. Remote Sensing, 14(14):3286.

[19] European Union (2022). Galileo High Accuracy Service signal-in-space interface control document (HAS SIS ICD), Issue 1.0. https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_HAS_SIS_ICD_v1.0.pdf.

[20] Montenbruck, O., Steigenberger, P., & Hauschild, A. (2015). Broadcast versus precise ephemerides: a multi-GNSS perspective. GPS Solutions, 19, 321-333.

Authors

Ding Yi is a Ph.D. candidate in the Department of Earth and Space Science and Engineering at York University, Toronto, Canada. Previously, he received his undergraduate degree in Geomatics from Wuhan University in China and obtained a master’s degree in Geomatics Engineering from the University of Stuttgart, Germany. Currently, his research interests involve precise point positioning (PPP) technology and multi-sensor integration.

Nacer Naciri is a postdoctoral fellow at the NASA Jet Propulsion Laboratory. He holds a Ph.D. from York University, Canada, as well as an aeronautics engineering degree from ISAE-SUPAERO in France, and an M.Sc. in aerospace engineering from KTH Royal Institute of Technology in Sweden. His research interests involve multi-GNSS, multi-frequency PPP-AR. 

Sunil Bisnath is a Full Professor in the Department of Earth and Space Science and Engineering at York University, Toronto, Canada. He received his Ph.D. in Geodesy and Geomatics Engineering from the University of New Brunswick. For over 25 years, he’s actively researched GNSS processing algorithms for positioning and navigation applications.

F. Javier de Blas is the Commercial and High Accuracy Service Manager at the EU Agency for the Space Programme (EUSPA). He has been leading the implementation of the Galileo HAS and CAS services, while actively contributing to Galileo Services’ Management activities within the Agency. He holds a M.Sc. degree in Aeronautical Engineering and a master’s degree in Airport and Air Navigation Systems from the Technical University of Madrid.

Roberto Capua is responsible for GNSS R&D at Sogei, the technological partner of Ministry of Economy and Finance of Italy. He received his master’s in Electronic Engineering from Sapienza Università di Roma and has 25 years of experience in the field of GNSS applications, research and development for public and private organizations. His areas of activity include advanced GNSS augmentation systems for high accuracy and integrity, GNSS software receivers and GNSS surveying.

The post Galileo HAS: A Performance Assessment in Urban Driving Environments appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

GMV is currently developing the ground control segment for the in-orbit validation (IOV) system for Galileo Second Generation satellites (G2G), under a contract signed recently with the European Space Agency (ESA). The contract exceeds €200 million in value, making a total of more than €500 million in contracts signed by GMV for work on the Galileo program since 2018.

The new ground segment will be used to control two G2G satellite platforms, which are currently in the design and production phase. The system will come into operation in 2025, coinciding with the launch of the first G2G satellite.

Getting set for G2G

According to ESA, G2G satellites will be much larger than first generation (G1G) satellites, using electric propulsion for the first time and hosting an enhanced navigation antenna. Digital payloads are being designed to be easily reconfigured in orbit, enabling Galileo services providers to actively respond to the evolving needs of users.

The new electric propulsion capability, which will be used to maneuver satellites from initial orbits into final, operational orbits, will mean two satellites can be launched at once, in spite of their increased mass. On-board technologies will include inter-satellite links, enabling routine cross-checking of performance between satellites and allowing reduced dependency on the availability of ground installations. The satellites will also feature more precise onboard atomic clocks, as well as advanced jamming and spoofing protection mechanisms to safeguard Galileo signals.

The ground segment

The new ground segment to be developed by GMV will provide control and monitoring capabilities for the G2G satellites, and will mark a technological leap forward compared to current systems. Innovations will include post-quantum cryptography, deployed microservices, improved automation, and new user interfaces, among others. The improvements will ensure the ground segment remains flexible, scalable, expandable, robust, and autonomous. Particular emphasis will be placed on aspects related to cybersecurity.

In 2018, GMV began work on the G1G ground segment, of which the company has already deployed the first of two contracted versions, currently providing services to a total of 28 satellites. GMV will continue to work on the G1G and the new G2G contracts simultaneously until the end of 2026, when Galileo’s ground control segment will be unified in order to manage the full 50-satellites constellation.

The post GMV Building Galileo Second Generation Ground Segment appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

A look at NTCM-G, a new Ionospheric model fully compatible with the Galileo Open Service. 

MATTEO SGAMMINI, FRANCESCO MENZIONE, JOINT RESEARCH CENTRE (JRC) OF THE EUROPEAN COMMISSION

RAUL ORUS PEREZ, EUROPEAN SPACE AGENCY

MAINUL HOQUE, GERMAN AEROSPACE CENTER (DLR)

The Neustrelitz Total Electron Content Model (NTCM) is an empirical model that in its NTCM-G variant has been adapted to operate with the broadcast Galileo Effective Ionisation Level coefficients. NTCM-G is a fully compatible algorithm used to compute ionospheric corrections for Galileo single-frequency users [1]. It provides a practical, cost-effective solution for determining global TEC and is proposed as an alternative to the NeQuick-G algorithm [2]. It is worth noting, however, that NeQuick-G will continue to be the reference algorithm for Galileo.

The model has been characterized and thoroughly tested and provides excellent performance similar to the current recommended solution using NeQuick-G, while its computational complexity is highly reduced. The reduced complexity and runtime of the NTCM-G algorithm are considered beneficial, particularly in user-segments where the equipment has limited resources available. This is typically the case for receivers used in civil aviation (i.e., avionics receivers) and location-based services (e.g., smartphones, smartwatches, UAV, IoT devices).

The NTCM-G model was developed by the German Aerospace Centre (DLR) and validated by the Joint Research Centre (JRC) of the European Commission and the European Space Agency (ESA). The description of the source code and its implementation were carried out jointly between DLR and JRC, with the European Union Agency for the Space Programme (EUSPA) and ESA supporting the review and publication of the model description. Users are invited to download the reference document “NTCM-G Ionospheric Model Description,” freely available at [3]. The document contains definitions, step-by-step procedures and guidelines for the implementation of NTCM-G in a GNSS receiver. The document also includes a dedicated section on the algorithm validation and data for the verification of independent implementations. The source code of NTCM-G is also available at [4]. The software package provides a portable and validated C/C++ implementation (Matlab and Simulink implementations are also available), including testing functions and testing vectors.

Model Description

NTCM is an empirical model [5] that provides a practical, cost-effective solution for determining global TEC. It makes use of 12 model coefficients, few empirically fixed parameters, and the solar radio flux F10.7 index. The original NTCM model has been further improved and adapted to work with daily proxy ionospheric correction coefficients, as in its NTCM-BC version described in [7]. A further adaption is the NTCM-Klobpar model [8], which replaces the driving parameter F10.7 by a so-called Klobpar parameter derived from the GPS broadcast coefficients. The performance analysis described in [8] demonstrated that the NTCM-Klobpar model achieves significantly better performance than the Klobuchar model. The analysis, based on TEC data from more than one solar cycle, compared the TEC modeled by the Klobuchar algorithm with the TEC modeled by NTCM-Klobpar, this latter providing 40% reduction on the average RMS during high solar activity periods and 10% during low solar activity periods. 

NTCM has been further adapted to operate with the broadcast Galileo Effective Ionisation Level coefficients (NTCM-G). For this purpose, the F10.7 index is replaced by a particular realization of the Effective Ionisation Level, called Azpar hereafter, which is computed using the three Effective Ionisation Level coefficients broadcast in the Galileo navigation message, i.e., (a_i0, a_i1, a_i2). Although these coefficients were optimized for NeQuick-G, their applicability to operate the NTCM has been demonstrated [5]. The investigation shows NTCM-G can be successfully driven by the Galileo broadcast Effective Ionisation Level coefficients. Azpar is used as a proxy measure of the solar activity level. The Azparexpression, given in Equation 1, has been analytically derived by taking the average root mean squared of the effective ionization level (Az) values for Modified Dip Latitude (MODIP) between 70° north and 70° south, and it is determined as follows:

The basic modeling approach considers five major dependencies of the vertical TEC (VTEC), i.e., local time dependency (F₁), seasonal dependency (F₂),geomagnetic field dependency (F₃),equatorial anomaly dependency (F₄) and solar activity dependency (F₅).The dependencies are combined in a multiplicative way as:

The five model functions F_i make use of 12 model coefficients k₁ to k₁₂ and a few empirical constants. The fixed model coefficients are derived based on a best-fit approach using as input Global Ionospheric Maps (GIM) from CODE and Azpar computed from the Effective Ionisation Level coefficients broadcast by Galileo during the 2013 to 2017 period. For additional details the reader is invited to refer to the official NTCM-G reference document on the European GNSS Service Centre (GSC) website [6].

NTCM-G is a two-dimensional VTEC model and therefore a mapping function (MF) is needed for the conversion of VTEC to slant TEC (STEC)

Where MF_MSLM is a Modified Single Layer Model (MSLM) mapping function in which ionospheric pierce point (IPP) height is used as 450 km.

Finally, in a first order approximation, the ionospheric propagation delay is inversely proportional to the square of the signal frequency (f) and directly proportional to the integral of the electron density along the ray path, i.e. the STEC and can be therefore obtained as: 

Software Implementation

A reference implementation of the core algorithm and the auxiliary functions described in [1] has been developed by the JRC in Ispra and is available for download on the GSC website [3]. The software package aims at providing a portable and validated C/C++ implementation of the model that can be easily deployed in different GNSS applications and simulation environments. Matlab and Simulink implementations are also available, including testing functions and several test vectors.

The development approach is based on modern industrial rapid prototyping practice of Model Based Design (MBD) using the Matlab/Simulink toolchain, followed by an auto-generated code into the target C/C++ application. This maximizes the code readability, improves the performance (i.e. memory and execution time) and achieves compatibility with common standards, as the MISRA C/C++ 2012 Coding Guidelines in this case. The MISRA C/C++ coding standard, originally designed for the automotive embedded software industry, is today widely used by embedded industries in safety critical applications, including aerospace and defense, telecommunications, medical devices, and rail. The design choice of the software implementation maximizes software reusability and modularity of each sub function, so the user can easily refactor or integrate each software component within their own solution. 

The <NTCM_Procedure_Core.slx> is the core function implementing the step-by-step procedure described in [1] and summarized in Table 1. Figure 1 depicts the Simulink structure and the functional blocks numbered with the corresponding step in the Table. 

Model Validation 

In this section, the performance of the proposed NTCM-G model is compared with that of NeQuick-G in both vertical and slant TEC and position domains. For additional and comprehensive results, the reader is invited to read [1].

Some of the analyses presented in this section classify the results based on the MODIP, which is a latitude related to the geomagnetic field. Additional details about the MODIP and how to compute it are available in [1].

Galileo further splits the MODIP into five different regions, which are given in Figure 2. Please note, that in the Galileo OS SIS ICD [4], navigation message fields have been reserved to potentially broadcast specific information about the state of the ionosphere in each of these regions.

NTCM-G performance in TEC domain

The NTCM-G and NeQuick-G model-derived VTECs are computed at each grid location and time epoch and compared with the corresponding reference VTEC values, taken from IGS VTEC products, IGSG. The model residuals (VTECmodel–VTECigsg) are determined and the corresponding mean, Standard Deviation (STD), and Root Mean Squares (RMS) are computed and enlisted in Table 2 for the years 2014 and 2015. It is worth noting the year 2014 corresponds to the solar maximum of Solar cycle 24. Additionally, considering that ionospheric effects are most dominant in the low latitude region during daytime hours, we also compared the model performance for the low latitude region 30° N–30° S at daytime hours 06:00-18:00 local time, and the results are summarized in Table 3.

By comparing the values in Table 2 and Table 3, NTCM-G residual statistics results indicate that NTCM-G provides accurate corrections, resulting in similar performances as those obtained using NeQuick-G.

To offer a glimpse of the geographical distribution of the error, the global VTEC RMS maps are depicted in Figure 3.
Looking at the equatorial regions, on both sides of the geomagnetic equator, NeQuick-G results in slightly larger RMS errors when compared to the NTCM-G model. This is true for both years. However, NTCM-G shows comparatively larger errors at around 60° S and 60° W geographic regions.

It is worth noting that the local accuracy and reliability of IGS VTEC products present geographically unbalances because it is highly dependent on the coverage (presence of GNSS stations) in a particular region. Continental areas, where the number of available ground stations is high, are in general more reliable and accurate than areas where the number of stations is low, like in the oceanic regions. The largest inaccuracies observed in Figure 3 in remote areas, like in the Pacific, can be partially attributable to a lower accuracy of the reference product.

The performance of NTCM-G and NeQuick-G is also assessed using independent Slant Total Electron Content (STEC) measurements computed at about 120 to 160 worldwide IGS ground stations using GPS SiS measurements and for every day in the period from March 2013 to December 2021. The NTCM-G and NeQuick-G model-derived STECs are computed at each station location for the same link geometries considering only elevation angles above 5°. The comparison is done in terms of STEC residual, which is defined as the difference between the modeled STEC and its corresponding STEC observation (i.e. STECmodel–STECobs), on a global scale and at the five MODIP regions. RMS estimates of STEC residuals are computed on a daily basis and over a total of about 10.6 billion samples. The results are plotted in Figure 4.

By comparing the RMS residual plots in all panels of Figure 4, we see the performance of both models is very similar and it can be concluded that there is no significant difference in performance between NeQuick-G and NTCM-G.

Analysis Over the Extended Period, 2000 to 2022

Galileo started broadcasting the Effective Ionisation Level coefficients in March 2013. To extend the availability of these coefficients even before 2013, ESA made use of a network of IGS receivers resembling the current Galileo network of sensor stations and derived past coefficients as they would be computed by the Galileo system. This allowed extending the analysis back to the year 2000, 
covering more than 23 years of data and extending over three solar cycles. 

Figure 5 depicts some noteworthy results based on the VTEC residuals computed over the extended period of 23 years. VTEC residuals have been sorted out based on the MODIP region and intensity of the proxy measurement of the solar activity level, Azpar. The plots display the 1-CDFs distributions for each range of Azpar of size 10. For each Azparrange, the 95th percentile is also displayed, together with the corresponding fitting curve over the whole Azpar extent. The plots give an insight on the distribution of the error a user can expect when adopting NTCM-G to compensate for the Ionospheric delay. 

Furthermore, the clear direct proportionality between the VTEC residuals and the intensity of Azpar (see dashed line in the plots) allows defining a proportional factor between the VTEC error at a certain latitude and the level of the proxy measurement, i.e. the values of the Effective Ionisation Level coefficients broadcast by Galileo.

NTCM-G Performance in Position Domain

The analysis on the positioning performance has been conducted at 47 global locations over the whole years of 2014 and 2019. Modeling errors, other than the residual ionospheric delay, are drastically reduced by implementing a PPP approach as described in [10], thus allowing for a complementary test of the error contribution due to the mismodeling of the ionosphere. Figure 6 shows the location of the 47 IGS stations used for the derivation of the positioning errors. It is worth noting the availability of each single station varies on a daily basis, therefore the effective number of stations effectively used on each day might be lower than 47.

For the performance analysis, the 68th, 90th and 95th percentiles are computed for each available station on a daily basis and then a 15-day global average is extracted, weighted by the number of stations available on each day. The following plots show the global mean for the years 2014 and 2019.

A comparison between NTCM-G and NeQuick-G for the 68th percentile of the 3D positioning error is given in Figure 8. The plot shows that the two models perform in a very similar manner.

Summary

This article presents a fully compatible algorithm to compute ionospheric corrections for Galileo single-frequency Open Service (OS) users, called NTCM-G. The global model provides a practical and a cost-effective solution for the determination of ionospheric TEC.

NTCM-G provides excellent performance, similar to the current recommended solution using NeQuick-G, while its computational complexity is highly reduced. A software implementation compliant to the MISRA C Coding Guidelines is available on the GSC website [3] and can ease code development 
targeting safety-critical applications. 

The reduced complexity and runtime of the NTCM-G algorithm are considered beneficial, particularly in user-segments where the user equipment has limited resources available such as receivers used in civil avionics receivers and location-based services such as smartphones, smartwatches, drones and IoT devices. It is safe to assume that NTCM-G can serve the needs of aviation users and to meet the stringent requirements of aviation receivers because of its simplicity and low computational cost.

References

[1]        European GNSS (Galileo) Open Service – Alternate Ionospheric correction algorithm for Galileo single frequency users, Issue 1.0, May 2022, European Commission (EC)

[2]        European GNSS (Galileo) Open Service— Reference Ionospheric correction algorithm for Galileo single frequency users, Issue 1.2, September 2016, European Commission (EC)

[3]        European GNSS Service Centre, website: https://www.gsc-europa.eu/

[4]        European GNSS (Galileo) Open Service Signal In Space Interface Control Document (OS SIS ICD), Issue 2.0, European Union, January 2021 

[5]        Hoque, M. M., Jakowski, N., Orús Pérez, R., “Fast ionospheric correction using Galileo Az coefficients and the NTCM model,” GPS Solutions, 2019, doi: 10.1007/s10291-019-0833-3.

[6]        Hoque, Mainul, Sgammini, Matteo, Menzione, Francesco, Perez, Raul Orus, & Chatre, Eric. (2022, November 16). Good performance, less computation: A new ionospheric model for the Galileo Open Service. https://doi.org/10.5281/zenodo.7326066

[7]        Hoque MM, Jakowski N (2015) An alternative ionospheric correction model for global navigation satellite systems. J Geodesy 89(4):391–406. https://doi.org/10.1007/s00190-014-0783-z

[8]        Hoque MM, Jakowski N, Berdermann J (2018) Positioning performance of the NTCM model driven by GPS Klobuchar model parameters. Space Weather Space Clim 8:A20. https://doi.org/10.1051/swsc/2018009

[9]        Hoque M M., Jakowski N., Cahuasquí J. A., “Fast Ionospheric Correction Algorithm for Galileo Single Frequency Users,” 2020 European Navigation Conference (ENC), 2020, pp. 1-10, doi: 10.23919/ENC48637.2020.9317502.

[10]      Orus, R., “Ionospheric error contribution to GNSS single-frequency navigation at the 2014 solar maximum”. Journal of Geodesy, 2017, 91, 397–407. https://doi.org/10.1007/s00190-016-0971-0

Authors

Matteo Sgammini is a technical officer at the Joint Research Centre (JRC) of the European Commission. He was a system and software engineer at MTU Aero Engines from 2006 to 2008. From September 2008 to April 2017, he was a research associate in the Navigation group of the Institute of Communication and Navigation at the German Aerospace Center (DLR), Germany. His research includes signal processing and estimation theory for GNSS. Currently, he focuses on GNSS integrity, Galileo Safety-of-Life services, and Galileo system performance verification.

Raul Orus Perez has a Physics degree from the University of Barcelona (UB) in 2000 and a Ph.D. in Aerospace Science and Technology from the gAGE/UPC research group of the Technical University of Catalonia (UPC) in 2005. Since 2010 he has worked in the Wave interaction and Propagation Section of ESA/ESTEC as a Propagation Engineer. His main focus is on activities related to radio-wave propagation in troposphere and ionosphere for supporting ESA missions.”

Mainul Hoque received his Bachelor in Electrical and Electronics Engineering in 2000 and was awarded a PhD in 2009 from the University of Siegen, Germany. Hoque has worked at the German Aerospace Center (DLR) since 2004. Since 2019 he has been the head of the Space Weather Observations department at the DLR Institute for Solar-Terrestrial Physics. He has many years of research experience with a focus in mitigation of ionospheric propagation effects including higher order effects in GNSS precise positioning, global ionospheric total electron content (TEC) modeling, three-dimensional ionosphere and plasmasphere modelling and mapping function modeling. He was/is involved and has contributed in many EU, ESA and national projects related to ionospheric research. He is the author/co-author of three patents and more than 90 peer reviewed journal papers.

Francesco Menzione received BE, ME, and Ph.D. degrees from the University of Naples Federico II in Aerospace Engineering and Satellite Navigation. After almost eight years of working in the aerospace sector as a control and software engineer, he joined the European Commission Joint Research Centre as Technical and Scientific Officer for the Galileo Sector. His main areas of research are GNSS navigation and GNSS based remote sensing. He is currently contributing to EU next generation space projects for precise orbit determination, Space Service Volume and LEO PNT systems.

The post Good Performance, Less Computation appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

As of August, 2023, operational Galileo GNSS satellites, with some exceptions, have been updated and are now transmitting an improved I/NAV message. Users will see an enhancement in the Galileo E1 Open Service (OS) performance in terms of robustness and a significant reduction in time to first fix in challenging environments, with both unassisted and assisted GNSS. Backward compatibility is assured, with no impact on legacy receivers and low complexity implementation within OS receivers.

Galileo satellites broadcast different types of data in four navigation messages: the F/NAV and I/NAV navigation messages, a commercial navigation message (C/NAV) and a governmental navigation message (G/NAV). The latest upgrade comprises new features added to the I/NAV message, carried by the E1-B signal.

New features

According to the EU Agency for the Space Program (EUSPA), the improved Galileo I/NAV signal now includes the Reed Solomon outer forward error correction (RS FEC2), enabling faster and more robust positioning. The RS FEC2 increases demodulation robustness at all times, enhancing sensitivity, while also improving overall time to retrieve clock and ephemeris data (CED) thanks to the broadcast of additional, redundant CED information. This allows the device to restore potentially corrupt data bits autonomously.

The reduced CED (RedCED) enables fast initial positioning, with lower than nominal accuracy, by decoding a single I/NAV word while waiting to receive the four I/NAV words carrying the full-precision CED. In combination, the new features allow users to obtain a rough first position much faster, while also significantly reducing the time required to obtain a first full-accuracy solution. The result is a much-reduced time to first fix, particularly when operating in difficult environments.

The improvements also benefit users working in assisted GNSS (A-GNSS) mode, through the new secondary synchronization pattern (SSP). In A-GNSS mode, when navigation data is received from non-GNSS channels, and when the receiver’s knowledge of the Galileo system time is affected by a relatively large error, clock uncertainty must be resolved quickly and reliably. With the I/NAV improvements, receivers can do this via the SSP feature, thus reducing TTFF in A-GNSS mode.

New I/NAV testing campaign

EUSPA is set to launch a testing campaign, open to receiver manufacturers, enabling participants to confirm the proper implementation and processing of the I/NAV improvements in their products. The tests will be conducted at the European Commission’s Joint Research Centre (JRC) in Ispra and at the European Space Agency facility in Noordwijk (ESA/ESTEC). Participants will be assigned to one of the two facilities depending on specific conditions and availability.

The post Galileo Implements I/NAV Improvements appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

The European Agency for the Space Program (EUSPA) is moving forward with its rollout of the free Galileo high accuracy service (HAS). Speaking at the recent HAS Days event in Spain, EUSPA’s Carmen Aguilera said, “Galileo HAS is user driven, as is the case for all European space programs. Our goal is to make sure that the services we are delivering are tailored to meet the needs of the users and the industries that will employ them in their businesses.”

EUSPA has recently launched a series of testing campaigns at the European GNSS Service Center (GSC) in Torrejon, aimed at assessing HAS performance in different application settings. “The accuracy of the performance of the service can differ, depending on the use case,” Aguilera said. “What is the speed, the dynamics? What are the obstacles and where is the user working? So we have been integrating and testing Galileo high accuracy in different dynamic user scenarios.”

One of the first testing campaigns has involved HAS being used in drone navigation, in cooperation with navigation technologies company Rokubun and Galileo operational service provider Spaceopal. Researchers flew EUSPA’s own ATMOS-8 fixed-wing drone out of the CATUAV/BCN Drone Center near Barcelona. The vehicle was equipped with a Rokubun MEDEA GNSS receiver.

“We performed, together with Rokubun, a series of flights where we collected gross signals,” said Aguilera, “and we then applied the HAS PPP corrections in post-processing, using the Rokubun JASON, HAS reference algorithm and other EUSPA tools. This allows us to compute the trajectories that would have been obtained if we had used a Galileo HAS receiver onboard the drone.”

The assessment of the obtained trajectories is ongoing and EUSPA will make the results available when the study is complete. “This is an example of kind of offline or post-processing testing that can be quite useful for those of you who might be thinking about using Galileo high accuracy for a specific application, but who may not know what kind of performance to expect. We can use this methodology to determine how good Galileo HAS would be for your use case at a very limited cost.”

EUSPA is currently undertaking similar tests of HAS performance in maritime navigation scenarios in rivers and ports in Ireland, in cooperation with the General Lighthouse Authority. All results are expected to be available in the fall of 2023.

The post EUSPA Testing HAS for Drone Navigation appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

Rokubun has developed and demonstrated a ready-to-use OSNMA library, enabling reception of trustworthy Galileo OSNMA navigation and positioning authentication information in a variety of GNSS solutions.

“We have managed to develop and validate a Galileo OSNMA client for tiny embedded microcontrollers,” said Rokubun CEO and co-founder Xavier Banqué Casanovas. “This opens the door to millions of devices with a GNSS chip and general purpose MCU to use Galileo OSNMA for authenticated navigation, against interference and attacks.”

Rokubun’s OSNMA Library has undergone extensive testing using official EUSPA test vectors, and its OSNMA algorithms have been validated under real conditions at the European Commission’s Galileo testing facilities at the Joint Research Center at Ispra, Italy.

“The key innovation lies in the fact that we managed to slim down the algorithm implementation to fit in very small MCUs platforms,” said Banqué. “This library is ready to roll out for users who want to announce Galileo OSNMA compatibility in parallel with the expected OSNMA service operations announcement at the end of 2023.”

Made to fit

The Rokubun Galileo OSNMA Library is compact and reliable and guarantees seamless integration and cross-platform support. Engineered in C with meticulous attention to MISRA compliance, it has been optimized for embedded and automotive platforms. It constitutes just 60 KB of code, needs only 15 KB of RAM, and does not rely on dynamic memory, and it is designed to be architecture- and OS-agnostic, allowing for smooth integration across various platforms.

“The new library fits every build system,” Banqué said. “It’s compiled with a tool chain for your architecture, and packaged as a single static library and header file, so adding it to any project is a matter of minutes.”

With the library loaded, the embedded platform receives the navigation messages from the host computer via the serial interface. It then decodes the OSNMA data and authenticates the navigation data transmitted by the Galileo satellites.

Made to move

The OSNMA library is designed to be as portable as possible, requiring only a working ASM and C compiler that supports ISO C99. A clean interface design ensures easy and fast integration. Rokubun has implemented a state-of-the-art hardware-in-the-loop (HIL) continuous integration, continuous deployment setup, to ensure optimal performance while validating user-specific enhancements, such as the utilization of cryptographic accelerators or other SoC/MCU specific resources. This setup continuously tests the library against several reference MCU targets, assessing its performance and guaranteeing its reliability.

Rokubun’s OSNMA library has been successfully cross-compiled and tested for various CPU architectures. Testing confirms it is compatible with X86, ARM Cortex-A (ARMv7-A), ARM Cortex-M, and Xtensa LX7 architectures.

The post Rokubun Unveils OSNMA Library for Embedded Platforms appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

The European Space Agency (ESA) recently awarded GMV with a contract worth more than €200 million to develop the ground control segment for in-orbit control and validation of Galileo Second Generation (G2G) satellites.

Europe’s Galileo provides positioning and clock synchronization services to more than 4 million users globally with a positioning accuracy of up to 20 cm. G2G will introduce new services, enhance existing technology and services, improve accuracy, strengthen system security and reduce maintenance costs, according to a news release.

The ground segment GMV is developing will control two new second-generation satellite platforms currently in the design and production phase. It’s scheduled to begin operation in 2025, which is when the first G2G satellite is slated to launch. A total of 12 satellites are expected to be launched over the next three years.

The ground segment will include many advanced features, including post-quantum cryptography, deployed microservices, improved automation and new user interfaces. The upgrades will make the system flexible, scalable, expandable, robust and autonomous.

The new agreement includes contracting core G2G activities, at a value of about €155 million. Activities will be carried out over 42 months from mid-2023 until the end of 2026, with options to extend to 2028.

A history of involvement

This isn’t GMV’s first contract for Galileo development. The company has been working on Galileo First Generation (G1G) since 2018, with contracts now totaling more than €500 million. GMV has deployed the first of the two contracted versions of the G1G ground segment, providing services to 28 satellites. GMV will deliver on both contracts simultaneously until the end of 2026. That’s when Galileo’s ground control segment will be unified to manage up to 50 satellites for constellation parallel replenishment.

Earlier this year, ESA awarded GMV a contract to develop the Galileo Second Generation System Test Bed (G2STB). G2STB will provide ESA with a key system verification and validation facility in support of its role of Galileo System Development Prime, enabling a wide range of Galileo system monitoring, troubleshooting, prototyping and experimentation activities.

A look at G2G

Once launched, the much larger G2G satellites will join the G1G satellites already in orbit. The new satellites will leverage electric propulsion for the first time, according to the ESA website, and feature an enhanced navigation antenna and fully digital payloads that will be easy to reconfigure in orbit for future updates.

Inter-satellite links between the satellites will enable them to routinely cross-check their performance and reduce their dependency on the availability of ground installations. The satellites will also feature more precise onboard atomic clocks and advanced jamming and spoofing protection mechanisms.

A leap forward

The ground segment, as well as the G2G satellites, will further enhance Galileo and the millions of users who rely on it for PNT, providing added protection and the ability to evolve with advancements in technology.

“In addition to providing control and monitoring capabilities for the future satellites, this new project marks a technological leap forward compared to current developments,” according to the release. “Development will be carried out for the first time in Galileo following the ‘Agile’ methodology, in order to support future phases of the system, and particular stress will be placed on aspects related to cybersecurity.”

The post ESA Awards GMV Contract for G2G Ground Control Segment Development appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

This year’s Munich Satellite Navigation Summit featured notable speakers and some notable absences. European, American and Chinese, but not Russian, representatives of respective GNSS programs updated attendees on progress and concerns.

At the Munich Satellite Summit opening plenary, Paraskevi Papantoniou, acting director for Space at the European Commission, discussed steps forward in a ‘crisis context’: “We continue to work toward our main EU objectives, of which there are three: the establishment of new data services, achieving net zero emissions and digitalization of the economy. We have some key space initiatives, including the development of new data services, and we have IRIS squared.” IRIS2 is the new European multi-orbital satellite constellation, put together in record time and offering enhanced communication capacities, including broadband, high-speed internet, to governmental users and businesses.

“We have launched the Galileo high accuracy service [HAS],” Papantoniou said, “with accuracy level of a few decimeters, for compatible receivers worldwide. This is the first ever free, global, precise positioning service and we’re inviting receiver manufacturers and app developers to use it.” Add the free OSNMA Galileo authentication service and the now running encrypted public regulated service (PRS) and you have a nice array of GNSS-alone-based services to brag about, if you’re the European Commission.

“We’ve been testing and tuning the OSNMA for the last few years,” Papantoniou said, “and we are confident that it is reliable and performing well. Our plan is to officially declare initial operations by the end of this year, but we know some manufacturers are already implementing this service, for both indoor and outside apps, for example trucks in Europe using the smart tachograph.”

Security Sooner Rather Than Later

As for the PRS, Papantoniou said, “We plan to declare PRS initial service next year. Together with ESA [European Space Agency], EUSPA [European Agency for the Space Program] and with industry, we are moving full speed. This is the last mile for us. In the current crisis context, it is important to have this governmental service fully operational.” Here, we suppose, Papantoniou, by ‘crisis context,’ was referring to the war in Ukraine.

“And of course,” Papantoniou said, “next to everything I’ve mentioned, in parallel, we are developing the second generation of Galileo satellites, with new and robust features, relying on ESA for design and also supervising industry. All of this ensures that Galileo will remain the top GNSS in the world, for ground, sea and air applications, but also providing services for space applications, for the GNSS space service volume.”

The absence of Russians, not only in Munich but more essentially at the European spaceport in Kourou, French Guyana, is indeed a crisis-level problem for the EU. As everyone knows by now, the Union has allowed itself to become heavily reliant on Russia’s Soyuz launch services over the years. Finding a way to get into space is now an immediate concern for the EU space program, while political principles continue to constrain its options.

“We want to rely on European suppliers for our flagship programs. This is enshrined,” Papantoniou said. “At the same time, in our EU space program regulation, one of the key objectives is to ensure autonomous access to space, through European Union providers. This is how we launch our satellites. There is also a strong governmental component, for example with the PRS, so we need to have the right security assurances. We are working very closely with our European service provider Arianespace, to see when we will be able to launch our next Galileo satellites, but for now, today, we are in a difficult situation, in a crisis situation.”

A Place for High Accuracy

Representing the U.S. GPS program, Harold ‘Stormy’ Martin, director of the National Coordination Office for Space-Based PNT in Washington, responded to the announcement of the new Galileo HAS: “The U.S. has long held the position that high-accuracy, precise point positioning [PPP] services should be provided by commercial services, so for decades U.S. companies have built PPP systems to meet the needs of their users. The U.S. belief is that the commercial market is best suited to adapt to those changing customer needs and provide the best product, so that customers can buy the level of accuracy that they desire, even if that desire changes over time.”

The Galileo HAS is delivered via the E6 radio frequency band, but the U.S. Federal Communications Commission (FCC) has not granted access to the Galileo E6 signal in the U.S., arguing that doing so could constrain its spectrum management in the future. The FCC last ruled on this in 2018, and its position continues to be a point of contention for the Galileo program.

“Spectrum use in the U.S. is a complicated issue,” Martin said, “involving multiple government agencies and commercial interests that are ultimately adjudicated by the FCC, which is an independent body. We can’t predict what the FCC would do in any given situation, but for context, E6 is not specifically allocated for radionavigation service in the U.S., and we do not have a GPS signal in the E6 band, so we can’t provide the protections for using Galileo E6 safely in that band. In the U.S. spectrum allocation process there is an allowance for submission of a reconsideration, but there is no guarantee that there will be a different outcome.”

A Place for Russia?

As widely reported, China and Russia signed contracts in 2022 to host ground stations for their respective GNSS, BeiDou and GLONASS. Beijing will place new ground monitoring stations at different locations in Russia, while Moscow will do the same in China. The two sides also recently signed a statement on the joint provision of support services to their customers. New ground infrastructure will likely boost the performance of both Chinese and Russian systems, enabling them to exploit new GNSS-based applications in areas such as precision farming, transportation and unmanned vehicles. Improved PNT services also will certainly benefit Chinese and Russian military users. Chinese-Russian GNSS cooperation is part of a broader partnership in space, which seemed to gather pace after the Western backlash against Russia’s 2014 invasion of Ukraine.

Jiang De, of the China Satellite Navigation Office in Beijing, was asked by session moderator Claus Kruesken to explain China’s ongoing cooperation with Russia, even as that country engages in aggressive warfare in Europe. His answer, though not exactly to the point, was an answer: “BeiDou adheres to the principle of cooperation,” he said. “China’s BeiDou is the world’s BeiDou, and so we cooperate with Russia, just as we promote cooperation and negotiation on satellite navigation applications and satellite communication with other systems, especially on the issue of compatibility and interoperability. I also believe that cooperation between different systems provides better services and applications to the global users. Again, we are not neglecting multi-lateral cooperation. We are doing joint performance assessment with other systems, and we are pushing to join more international organizations. We are implementing education and training programs to cultivate talents across the world. In a word, BeiDou has always promoted the capability, construction and technology development of satellite navigation.”

Stormy Martin told Inside GNSS he felt no awkwardness in sharing a stage with China at what could be seen as a fragile time in U.S.-Chinese relations. “I think it’s important to realize that there are a lot of users out there that use all of these systems every day,” he said. “They may not realize it, but if you go into the guts of cell phones, for instance, a lot of them have a chip that uses GPS, GLONASS, BeiDou and Galileo. Now, in different countries, different parts of that chip may be activated or may not. It depends on exactly what location they’re in and what the manufacturer of the cell phone decides to enable, but there are people all over the world that use all of these systems, so it’s important to focus on those customers. What can we do to make our systems better for them, because they rely on us for safety-of-life response, fire, ambulance, police, safety of aviation, in the air, and then all of the commercial uses which have changed our lives dramatically.” So the American and Chinese delegations, at least in Munich, seemed not to be of a mind to bicker. “And meanwhile,” Martin said, “we can continue to hope the world becomes a more peaceful place.”

Galileo PRS Push

As it waits for the world to become more peaceful, the European Union is forging ahead with its plans to beef up GNSS security. The characteristics and architecture of the Galileo PRS have already been outlined elsewhere. Fabien Frossard, service engineering manager at EUSPA, said, “The Galileo dual frequency, E1 and E6, certified and accredited PNT service, what we call the PRS, is managed by EU member states, accessible to them as well as to third countries and international organizations, subject to conditions.” Third countries currently enjoying access to the PRS include Norway and the U.S., and we have it on good authority that Great Britain also will be granted access in the near future, subject to the outcome of ongoing negotiations.

“We have been in the initial service phase since 2016, when we started to broadcast the signal in space,” Frossard said. “Right now, we are preparing the operational qualification of the new PRS release. That’s to say we are about to finalize the deployment of system build 2.0. And of course we manage the PRS access control from the Galileo Security Monitoring Centers in France and in Spain.”

Frossard outlined a number of current tasks being undertaken by EUSPA in its push toward PRS full operational capability. One of these entails providing PRS expertise to member states. “And we are doing the same on the other side for industry,” he said. “We are also helping to fund and coordinate R&D projects. We are now deploying across Europe a Galileo robust operational network [GRON]. This is a classified network used to disseminate the PRS keys all across Europe, giving users access to PRS signal.”

Next steps include supporting more R&D projects, for example toward the development of new PRS receiver
prototypes. One project, designated P3RS2, has already produced a prototype. “This was our first one,” Frossard said. “It’s a sort of shoe box unit, and we’re now going deeper, step by step, to reduce the form factor. We have another one under development, with the Leonardo-designed project P3RSE. This is a compact, dual-constellation receiver, much smaller than the first one.” The new prototype is designed for both land and maritime tactical platforms. It is tamper proof and it hosts Galileo PRS compact secure receiver type I (GSRT1) using Galileo OS and PRS, and GPS C/A, and there is an option for military GPS (SAASM).

“We are also preparing a radio frequency constellation simulator [RFCS],” Frossard said, “for which we have published a tender. This will simulate the constellation signals in space in different environments, as received at a specific position and date, to test and validate receivers and security modules before mass production, and for the investigation of incidents.” The unit will have full simulation capabilities in all Galileo bands, plus GPS and others.

Finally, a new project with Airbus and Fraunhofer is developing a test vector generator. “This is an ongoing project,” Frossard said. “It will give us a simulation tool for the whole industry that can be used by member states to simulate PRS orders and messages, for the development of PRS receivers and security modules.”

More Coming

“For the future, we will continue to support member states’ competent PRS authorities [CPAs],” Frossard said, “and of course we have many activities on the user segment aimed at promoting ease of access to the PRS. We are keen to be supportive to PRS uptake, and EUSPA’s idea is to help member states and the industry to propose innovative solutions for the PRS user segment. Therefore, we are launching a number of actions through the Horizon program [the EU’s R&D funding framework] and to develop PRS-based applications with the competent PRS CPAs.”

Following Frossard, Frank Wilms of FDC and Ronald Nippold of DLR presented work under ongoing EU-funded R&D projects, aimed at developing and demonstrating a range of new PRS-based technologies and applications.

There were many other extremely enlightening presentations given at the Munich Satellite Navigation Summit. In all, the event felt a bit like a class reunion. After an extended break, due to health concerns, the Bavarian capital was found to be everything that it had been before. The summit featured familiar faces and some fresh ones, and in spite of the missing GLONASS delegation, the event was informative and encouraging, and one could hardly have wished for more than that.

The post Brussels View: Highlights From the Satellite Navigation Summit appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

Businesspeople, politicians, civil servants and a range of engineers and researchers gathered in Brussels for the 15th European Space Conference in January. Topics were many and varied, with war, dependency, resilience and a big-time launcher crisis heading the list.

One subject, more than any other, preoccupied attendees of this year’s European Space Conference. In a stirring welcome address, High-Representative/Vice-President of the European Commission Josep Borrell Fontelles told the assembly, “One year ago, we were just on the eve of war. Now, we are in the middle of a war, so the security of Europe in space is a very timely subject.” Our regular readers know that subject has been very timely for a while.

“Last year,” Borrell continued, “we stressed the increased level of threats in the space domain, and we now believe we need a change of paradigm. Space will become a kind of battlefield, of competition and confrontation. Satellite imagery and communications have proved to be game changers for the Ukrainian armed forces and the civilian population.”

Borrell recalled the cyber-attack on Viasat on the night of the Russian invasion that knocked out communications for several days, affecting neighboring countries as well as Ukraine. “This has revealed our own vulnerabilities,” Borrell said, “affecting our own member states. These are critical infrastructures that we need. If they fail, our economies, our entire lives, will be disrupted. In 2021, Russia tested a kinetic anti-satellite weapon. It was an irresponsible act that signaled to anyone that Russia is prepared to put anyone’s satellites at risk.”

Timo Pesonen, director-general, DG DEFIS, European Commission, also recalled the days just before the start of the war. “A year ago, if somebody in this room had asked who thought Putin was going to attack the capital of Ukraine in one month’s time, I’m not so sure how many of us would have raised our hands. Of course, there was intelligence information around that he was gathering troops at the border, but I think we were all hoping for a miracle to happen.”

What They Thought About That

The 15th edition of the conference was a return to form, that is to say a return to format. Two years ago, In 2021, the conference was mostly a ‘virtual’ online affair, due to the crisis we need not name. Then, in 2022, it went back to being held in person, but many habitual attendees stayed home, choosing to keep their distance until the coast was well and truly clear. By all accounts, that edition was a rather forlorn affair.

This year’s event felt like old times. The big plenary room was full to bursting, everyone was breathing deeply and the lunch hall, lobbies, corridors and side rooms were abuzz. And, as they will, fresh from the affray in the big room, people exchanged views candidly once outside. Having heard a number of high-profile presenters expressing their surprise and dismay at the events of February 2022, more than one corridor commentator expressed their own surprise at the surprise. “Didn’t Russia invade Georgia a few years ago?” said one, off the record. “Didn’t they just annex Crimea?”

Another well-known personality at the conference whispered, confidentially, “We were hearing every day from the intelligence experts. Of course we could see what was about to happen. There was no surprise.” Still another participant cited the regime in question’s repeated past “criminal” actions, saying the surprise was perhaps more about the absolute scale of the thing.

In 2017, Inside GNSS published an article titled, “EU and Russia: Lost in Space?” that questioned the advisability of maintaining a dependent relationship with Russia in the wake of that country’s aggressive actions against a familiar target. According to the article:

In April, the United States officially pulled the plug on almost all space cooperation with Russia as a result of the latter nation’s intervention in Ukraine.

According to a Space News report, cited in the 2017 article, Europe did not follow suit:

At the height of the bloodletting in eastern Ukraine last June, ESA [European Space Agency] Director-General Jean-Jaques Dordain said, “The European Space Agency has seen no signs that its relations with Russia will be curtailed as a result of the confrontation between Russia and the West concerning Russia’s actions in Ukraine.”

Even though:

Speaking in Brussels, one unnamed European official said, “The situation in Ukraine is very tense indeed, with many obvious consequences on the relationship between Russia and Europe.”

The Launcher Crisis

So much for warning signs. Europe now has a very present situation to contend with. In an era of ever-accumulating crises, we may add another: ‘The European Launcher Crisis.’ Borrell said, “This war was a wake-up call. We are becoming much more aware of the dependencies on foreign suppliers. For example, when the Russian Soyuz teams suddenly left the spaceport of Kourou, they put in danger our launch capabilities.”

“WE BUILT GALILEO IN RESPONSE TO AN EXISTING NAVIGATION NETWORK THAT WE ALL KNOW VERY WELL. TODAY, GALILEO IS PROVIDING THE MOST ACCURATE SIGNAL FOR NAVIGATION, FOR POSITIONING, AND THIS IS SOMETHING WHERE EUROPE CAN BE VERY PROUD.”

Josef Aschbacher, high-representative/vice-president, director general, ESA

But war isn’t the only problem. Josef Aschbacher, Director General of ESA, in his presentation of 2022 highlights, acknowledged other setbacks: “We had the successful launch of our MTG satellite on the 13th of December [onboard Ariane 5], but also just before Christmas, on the 20th of December, we had the failure of our Vega-C launcher, after we had had a successful inaugural flight in July, earlier in the year.”

According to reports, the Vega-C’s Zefiro 40 second stage deviated from its intended trajectory following a loss of pressure, resulting in reentry over the Atlantic, less than 1,000 km from its launch site. Two Airbus Defence and Space dual-use Pléiades satellites were lost in the misfire. Zefiro is a family of solid-fuel rocket motors developed by Avio.

“And this puts Europe in a very critical situation on launchers,” Aschbacher said, “due to the situation of our delays on Ariane 6.” Also in 2022, ESA again delayed the first flight of Europe’s Ariane 6 launcher, this time to late 2023.

“With this, and with the halt of the Soyuz launches from Kourou and the Vega-C failure, Europe is in a very serious situation. Guaranteed access to space is a top priority for Europe, for ESA, for all of us, because if we cannot guarantee access to space, we will seriously shut down launching of infrastructure on which we depend.” That includes completed Galileo satellites currently sitting on the ground, ready for launch.

Aschbacher said it is crucial to get Ariane 6 and a safe and functioning Vega-C onto the launch pad as quickly as possible, “but we also need to invest in the future, to engage a new group of launchers, micro-launchers, mini-launchers. And later we will need reusable launchers, after Ariane 6 and Vega-C. This is a weakness of Europe today.” Stéphane Israël, CEO of Arianespace, agreed: “In the long term, we will need a heavy, reusable launcher. For the European flagship programs, Galileo and so on, you will need a big launcher, no doubt.”

For now, the waiting goes on. A spokesperson for ESA told Inside GNSS the agency is actively seeking a solution for launching grounded Galileo satellites, which can include non-European (and non-Soyuz) launchers.

Self-Reliance Versus Dependency

An unintentionally provocative take: For all its ingenuity and scientific excellence, and in spite of Jules Verne, Europe has lagged behind as a source of inspiration in space. At the height of the Cold War, the U.S. and the Soviet Union drew the hearts and minds of the world toward the stars, on the tails of their military-fueled space race. Today, the Chinese government has managed to link its space program to the country’s immense sense of pride and their belief in its extraordinary destiny. Europe, on the other hand, for all its technical achievements and steady reliability, has remained a rather polite, very competent but otherwise low-key partner seeker. Not, one should add, without success.

Aschbacher said, “We built Galileo in response to an existing navigation network that we all know very well. Today, Galileo is providing the most accurate signal for navigation, for positioning, and this is something where Europe can be very proud.”

Miguel Romay, general manager navigation systems, GMV said, “When I started in navigation more than 30 years ago, Europe was completely out of the game. We had GPS, GLONASS and nothing from Europe. We started to move toward satellite navigation, dreaming about having something similar to what the Americans had.”

Must Europe always turn to others for inspiration? In this time of geopolitical turmoil and economic uncertainty, who will serve as Europe’s model? And on whom will it depend for help?

”EIGHT YEARS AGO, I FLEW TO SPACE ON A RUSSIAN VEHICLE, THE SOYUZ. A YEAR AGO, I FLEW ON A U.S. VEHICLE, NOT EVEN A GOVERNMENT VEHICLE BUT A VEHICLE PROVIDED BY A PRIVATE COMPANY AS A SERVICE. YOU HAVE THAT EXPERIENCE AND YOU START TO SCRATCH YOUR HEAD, AND THINK, ‘WELL, THIS IS GREAT. I LIKE INTERNATIONAL COOPERATION, BUT WHAT ABOUT FLYING IN A EUROPEAN VEHICLE?’”

Samantha Cristoforetti, ESA Astronaut

“We cannot implement the U.S. model,” Israël said. “The U.S. spends five times more on space than Europe. We can take some lessons, but the copycat strategy will not work. And this should not be about Europeans competing against each other. This is the U.S. and China competing against Europe. It’s time to organize the industrial base in order to compete. We see how it goes in the U.S., with the Inflation Reduction Act, how they have changed overnight the competitiveness of their companies against us. Let’s not be naive, let’s take the bull by the horns and make it happen.”

André-Hubert Roussel, president of Eurospace, said, “We don’t benefit from the measures that have been put in place by some of our competing nations, specifically for the U.S. industry. We are facing nearly 10% inflation in Europe. It’s going to cost our space industry 500-750 million euros in extra costs this year. We have to tackle this with our partners, starting with ESA and the EC [European Commission]. We need venture capitalists, and we need to make sure we have a level playing field with the U.S.”

Aschbacher said, “Today, Europe is not capable of launching its own astronauts, with its own capabilities, into space, because we are flying with our good friends and strong partners of NASA, the Americans. In the past few years, we were flying with Russia, but if you look 10 years into the future, I think Europe should seriously consider having its own capability. This is much bigger than space. It is geopolitical, it is societal, it is about the unity of Europe. We are not fast enough and we are not bold enough.”

Speaking of astronauts, ESA Astronaut Samantha Cristoforetti said, “Eight years ago, I flew to space on a Russian vehicle, the Soyuz. A year ago, I flew on a U.S. vehicle, not even a government vehicle but a vehicle provided by a private company as a service. You have that experience and you start to scratch your head, and think, ‘Well, this is great. I like international cooperation, but what about flying in a European vehicle?’ At this point, the question is what’s wrong with us? Why do we not have that ambition?”

”GALILEO HAS BEEN DESIGNED TO BE VERY ROBUST.
THE SPECTRUM OF SERVICES THAT ARE BEING DEPLOYED, STARTING FROM THE BASIC SERVICE, ADDING AUTHENTICATION, THE HIGH-ACCURACY SERVICE, THE PRS [PUBLIC REGULATED SERVICE], EMERGENCY SERVICES THAT WILL BE DEPLOYED IN THE FUTURE, SAFETY-OF-LIFE, WHICH IS PROVIDED BY EGNOS, ALL THIS NEEDS TO BE ASSURED.”

Javier Benedicto, director of navigation, ESA

“We live at the end of an era of happy globalization,” said Thomas Dermine, Belgium’s State Secretary for Economic Recovery and Strategic Investments, in charge of Science Policy. “We see a rise in geopolitical tension, we see commercial tension, we see a rise in protectionism. If you look at the American Inflation Reduction Act, it impacts all sectors. It is going to impact the space industry. A few years ago, we were seeing all kinds of cooperation with other parts of the world. We see today that our cooperation with Russia is completely ended. In China we see rising tension, and even with the Americans. We need to rely more on our own capabilities, because you don’t know what the future will be.”

Then Came PNT

Amid all the soul-searching, conference attendees suddenly found themselves faced with a series of presentations on what it all means for the positioning, navigation and timing troops. “It was already there before the war,” Pesonen said, “but the war has certainly underlined it. Resilience is a key word for us.”

”WE ARE OFFERING SERVICES THROUGH DIFFERENT SIGNALS, AT DIFFERENT FREQUENCIES, AND THIS IS PRETTY GOOD AGAINST INTERFERENCE. THEN WE HAVE OUR AUTHENTICATION SERVICE, WHICH IS COMING UP THIS YEAR, AND THERE WE WILL BE PRETTY GOOD AGAINST SPOOFING. WE CAN SPEAK ABOUT THE SECOND-GENERATION SATELLITES, WHICH ARE GOING TO PROVIDE MORE ROBUST SIGNALS.”

Paul Flamant, Head of Unit, Satellite Navigation, DG DEFIS, European Commission

Paul Flamant, Head of Unit, Satellite Navigation, DG DEFIS, European Commission, assessed the state of resiliency of Europe’s GNSS systems: “We are offering services through different signals, at different frequencies, and this is pretty good against interference. Then we have our authentication service, which is coming up this year, and there we will be pretty good against spoofing. We can speak about the second-generation satellites, which are going to provide more robust signals.

“But also,” he said, “it’s very important in terms of satellite navigation resilience that we keep our good agreements with those brilliant people that are on the other side of the Atlantic. We have agreements with the Americans, and it is very important that we continue this collaboration.”

Flamant also cited the EU’s European Radio Navigation Plan. “I invite people to read it,” he said. “In it, we call on people to come up with new resilience solutions, and we’ve been trying to see what really needs to be done, in terms of navigation but also in terms of timing. There were the workshops organized recently at the Joint Research Center at ISPRA, where we could see what other timing and navigation systems exist.”

“From the point of view of operations,” EUSPA Executive Director Rodrigo da Costa said, “we have two control centers, we have two security monitoring centers, so there’s a lot of resilience in there, but we also exercise that resilience. We carry out simulations, a number of simulated situations, working with our external action service, where we simulate techniques and responses. This is incredibly important in order to ensure the preparedness of our operational teams.”

A New Architecture

ESA Director of Navigation Javier Benedicto said, “Satellite navigation really has a very strategic dimension for all of us. It has become a commodity with respect to our daily life. It contributes to economy, but also to implementing government policy. This fundamental nature creates a notion of dependency. We depend every minute on it, and therefore there is an expectation on the part of users. These are systems that have to work all the time.

“This in turn creates responsibility, for the people who conceive the system,” Benedicto said. “Galileo has been designed to be very robust. The spectrum of services that are being deployed, starting from the basic service, adding authentication, the High-Accuracy Service, the PRS [public regulated service], emergency services that will be deployed in the future, safety-of-life, which is provided by EGNOS, all this needs to be assured.”

Benedicto outlined the new LEO PNT program adopted at the most recent ESA ministerial conference. “This program is the largest in the world of its nature,” he said. “It brings a new dimension, not based anymore on geostationary or MEO satellites but also on LEO satellites. The trick of the business is to interconnect all that from the user perspective. The user does not know or care if the signal is coming from a LEO or a MEO or GEO satellite.

“We will also see an evolution affecting the EGNOS service, today based on geostationary signal broadcast, but in the future also to be broadcast most probably from MEO and LEO satellites. And we see a future in deploying navigation signals in new frequency bands, not only in the L band but also in lower bands and higher bands. All this leads to a multi-layered PNT architecture.”

A Constellation for Digital Resilience

IRIS2 (Infrastructure for resilience, interconnectivity and security by satellite) is the EU’s newest space-based infrastructure, being mounted in record time and offering enhanced communication capacities to governmental users and businesses, and delivering high-speed internet broadband in connectivity dead zones. Initial services are scheduled for launch as early as 2024, with full operational capability by 2027.

Benedicto said, “IRIS2, Galileo and EGNOS all have to be connected, because, at the end of the day, we want to reach the smartphone, we want to reach the airplane cockpit, the dashboard of the autonomous vehicle, and this requires a combination of sensors and techniques for both communication and navigation. This will require the use of optical technologies, quantum communication, quantum encryption, and with all of this, I am sure that Europe will remain at the forefront of resilient PNT.”

On that very inspiring note, we leave the 15th European Space Conference, with apologies to all who were not cited. We will meet again, and so say not adieu, but au revoir. Until next time…

The post Brussels View: European Space Conference 2023 Takes a Hard Look appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

GMV is selected by the European Space Agency (ESA) for the development of the Galileo Second Generation System Test Bed (G2STB)

The G2STB is one of the Key infrastructure elements that ESA is developing for the correct functioning of the Galileo second generation satellites

The contract ceremony was performed on March 10 at the GMV´s headquarter

The European Space Agency (ESA) acting on behalf of the European Union Agency for the Space Programme (EUSPA) and in the name of the European Union represented by the European Commission (COM) has awarded technology multinational GMV a contract for the development of the Galileo Second Generation System Test Bed (G2STB).

The G2STB will provide ESA with a key system verification and validation facility in support of its role of Galileo System Development Prime, enabling a wide range of Galileo system monitoring, troubleshooting, prototyping and experimentation activities.

The G2STB project will ensure a smooth transition from the Galileo First Generation (G1G) to Second generation (G2G), capitalizing and building on the heritage of key G1G legacy system tools. In particular, the G2STB is one of the key infrastructure elements that ESA is developing for the correct functioning of the Galileo Second generation satellites. This new generation of satellites represents a major step forward for the Galileo constellation, incorporating numerous technology updates. ESA has prepared new procurements to ensure that the key technology elements required in the G2G ground segment are properly covered.

The G2STB will eventually replace and upgrade with state of the art capabilities two G1G existing facilities, the Galileo System Evaluation Equipment (GALSEE) and the Time and Geodetic Validation Facility (TGVF-X). The latter, developed and operated by GMV over the last decade, has played a key role in monitoring the Galileo signals and system validation activities during the Galileo Exploitation Phase. The TGVF-X is also contributing to the early validation of new capabilities and elements being rolled out in recent and upcoming Galileo System updates.

Under an iterative development approach and continuous evolution based on Scaled Agile Framework (SAFe), GMV will deliver four major G2STB versions over a period of five years. This methodology will ensure a continuous value delivery in the development of the different System capability Prototyping modules (ScPMs) of the G2STB. Among these modules, the G2 HAS data generator and monitor is of significant importance as it aims at further improving the Galileo High Accuracy Service (HAS), recently declared operational and for which GMV has also played a key role. Other G2 Early Capabilities of the G2STB comprise an upgraded Orbit Determination and Time Synchronization facility capable to process Inter Satellite Link data, a Time Service Monitoring module, an Integrity Support Message generator, a Signal Authentication Service (SAS) /Authentication validation module, an Emergency Warning Service (EWS) module, an ISL simulator and a G2G Message composer.

In parallel to the development phase, the G2STB will ensure the upgrade of the network of Galileo Experimental Sensor Stations (GESS) to cope with the new signals and capabilities ensuring the availability of a G2 capable worldwide multi constellation network of receivers and bit-grabbers, independent from the operational Galileo Sensor Stations (GSS).

As project leader, GMV will lead a consortium of more than twenty partners including Thales Alenia Space Italy as core team member and a total number of 20 entities from 8 different European countries. Without question, this milestone strengthens GMV’s role as a top-level participant in the Galileo program.

In words of Miguel Romay, GMV’s Navigation Systems General Manager, “We are delighted that ESA has once again placed its trust in GMV’s experience and expertise. This new contract will undoubtedly highlight the great effort GMV has conducted over the last decade as key partner in the definition, implementation, and monitoring of the Galileo system.”

“The G2 System Test Bed is the first of wide set of Galileo Second Generation key procurements currently ongoing, which will ensure that Europe will continue to be the leader of GNSS services in the next 2 decades. In particular, the G2STB will provide a critical role in the definition and optimization of all Galileo services improvements and new G2 Service capabilities, to be validated as soon as the first G2 satellites are launched”, stated Miguel Manteiga Bautista, ESA Galileo Second Generation Project Manager.

Graphical system view

Contract signing ceremony

The contract ceremony was performed on March 10 in GMV´s headquarters offices. Presents at the signing event were Jesús Serrano, CEO of GMV; Miguel Romay, Satellite Navigation Systems General Manager, hile on behalf of the European Space Agency were, Ennio Guarino, Head of the Galileo Programme Department and Miguel Manteiga Bautista, Galileo Second Generation Project Manager.

The post GMV Will Develop the Future Galileo Second Generation Capabilities appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.