ABSTRACT. The National Positioning Infrastructure Capability (NPIC) is a program aimed at establishing the necessary ground infrastructure to track, verify and optimise data for precise GNSS positioning across Australia. The envisioned network will contain approximately 200 Continuously Operating Reference Stations (CORS) well distributed over the Australia's landmass, each capable of tracking multiple GNSS constellations. The interstation distance of such a CORS network is expected to be between 250Km and 300Km, which is relatively sparse compare with networks currently used for network RTK. The research described in this paper is part of efforts to develop ionospheric model for PPP-RTK based on measurements from the NPIC network. Ionospheric modelling is expected to be key in maximising the value of the NPIC. Models that can estimate ionospheric delays in GNSS measurement with an accuracy of 5cm or better will enable precise positioning services with convergence times of a few minutes. This paper will present the effectiveness of three ionospheric modelling: STEC interpolation, b-splines and spherical harmonic caps; when applied to networks of similar density. Ionosphere delay maps will be estimated baser on the three different techniques will be estimated and evaluated based both on the accuracy of the ionosphere delay accuracy and the convergence time of PPP-RTK positioning solutions.

ABSTRACT. Geoscience Australia (GA) maintains one of the most complete public repositories of Global Navigation Satellite System (GNSS) data from continuously operating reference stations across the Asia-Pacific region. The data sets found in this repository define Australia’s national datum, contribute to the IGS and support numerous academic, government and industry projects. In a continuous effort to modernise our data centre workflows and procedures, we have developed a new event-driven GNSS data management system hosted in Amazon Web Services. This new data repository system helps users discover, interact and extract well over 100 million RINEX files not only using traditional file transfer protocol (FTP) but also using secure HTTP APIs with minimum monthly uptime percentage 99.99%.

ABSTRACT. National vertical reference systems have traditionally been based on classical levelling techniques and tide gauge observations. Practical realisation of such datums is challenging. The improved accuracy of height determination and the high quality of horizontal reference datums based on GNSS technology calls for a change in the way we define and realise vertical reference datums. While some countries still have viable vertical networks, many countries do not. Over the last few decades many benchmarks, which are the practical realisation of a vertical datum, have either been destroyed or have shifted. Therefore geodesists around the world nowadays are interested in a new realisation of national vertical datums using GNSS technology. In order to obtain physical heights from the ellipsoidal heights measured by GNSS receivers, a geoid/quasi-geoid surface model is required. Hence, apart from the accuracy of the ellipsoidal height measurements, the quality and resolution of the national geoid model is the major contributor to the accuracy of a national height system. The area of interest for the definition and realisation a new vertical reference datum is Costa Rica. Costa Rica is a small country but challenging in terms of gravity field modelling due to its geography. With coasts on the Pacific Ocean and Caribbean Sea separated only by as little as 100km, and in between with tropical rainforest, mountain ranges and volcanoes as high as 3820 metres, Costa Rica has an inhomogeneous gravity data distribution and large data gaps in the National Park Conservation Areas. To address these challenges, the authors use the latest advances in geodetic techniques: GRACE/GRACE-FO and GOCE satellite gravity data, an accurate digital elevation model, rigorously examined historical marine and terrestrial gravity measurements, and marine models that were obtained with the high-resolution Cryosat2 altimetry mission. This presentation describes the datasets and procedures that have been adopted for the improved Costa Rican vertical reference datum.

ABSTRACT. A Corner Reflector (CR) is an artificial radar target, which can be used to detect surface movements with the Interferometric Synthetic Aperture Radar (InSAR) technique. Co-located to a GNSS site, CRs provide the possibility to compare and validate ground deformation measured by GNSS and InSAR. From a validation perspective, it is advisable to have CRs located in close proximity to the GNSS site, preferably coupled to the same platform or attached to a GNSS monument. However, with regards to GNSS data quality, the metal CRs should have no or only minor impact on the GNSS observations. Multipath effects resulting from reflection of GNSS signals by a CR are a potential source of interference for GNSS observations at a site co-located with CRs. In this contribution, we investigate the multipath effects at five continuously operating sites with co-located CRs in the Sydney Basin area. Four of the sites were newly constructed in 2016 with two CRs being directly attached to the GNSS monument at each site. One GNSS site was already operating since 2010 and had two CRs retrofitted to the existing monument in 2016. At this site, we statistically assess the changes to the coordinate time series resulting from differential GNSS processing for the three-year periods before and after CR deployment. At all five sites, we generate multipath maps by spatially stacking the phase residuals resulting from individual PPP analysis at each site. We find that multipath effects related to the CR structures are present at all five sites, but small compared to multipath effects induced by other infrastructure surrounding a typical GNSS site. Furthermore, the magnitude of the multipath effects strongly depends on the quality of the antenna used at a site, and is almost negligible for high-quality choke ring antennas, such as used in the Australian CORS network.

ABSTRACT. The center of space technology and microgravity (ZARM) at the university of Bremen in Germany is working on high precision models for non-graviational accelerations improving orbit propagation and determination. We give a quick overview on the modelling methods and some applications involving space geodesy (GRACE), GNSS (GALILEO) and fundamental physics missions (MICROSCOPE).

ABSTRACT. To facilitate the real-time precise GNSS positioning, Geoscience Australia is developing an Analysis Centre Software (ACS) package to produce multi-GNSS orbit and clock products. The dual-frequency ionosphere-free observations from GPS (L1&L2), BeiDou (B1&B2) and Galileo (E1&E5a) are used to eliminate the first-order ionosphere effect. By combining the partials from the precise orbit determination (POD) component and the partials related to GNSS observations, the Extended Kalman Filter (EKF) is adopted to estimate the parameters including the satellite orbit adjustments, epoch-wise satellite and station clocks, the zenith wet delay and the ambiguities. To validate the results, we have processed multi-GNSS data from ~100 globally distributed stations, and the estimated satellite orbits and clocks for GPS, BeiDou and Galileo constellations are used for analysis. Our initials comparisons with the International GNSS service (IGS) final products show that the ACS estimated 3-D orbit RMS differences are at the ~5cm level for GPS, ~10cm level for Galileo. The BeiDou orbit 3-D RMS differences range from ~10cm to ~1m depending on the satellite type, e.g., MEO, IGSO or GEO. Comparison of the estimated satellite clocks against IGS final products typically shows RMS differences of ~3cm for GPS clock, and ~6cm for BeiDou and Galileo satellite clocks.

ABSTRACT. The Trimble CenterPoint RTX positioning service delivers real-time centimeter-level accurate positioning for standalone GNSS receivers. It is based on the estimation of precise satellite orbits, clocks and biases as well as atmospheric models computed from the data of a worldwide network of GNSS reference stations. The correction data is transmitted to the user receiver via L-band from geostationary satellites or via the internet. Using pseudorange and carrier phase observations together with the received correction data, the user can perform absolute cm-level accurate positioning anywhere on Earth. By using all current GNSS an accuracy of 2.5 cm (95%) is achieved after a convergence time of less than 15 minutes (95% of the time) globally or less than 1 minute when using regional ionospheric and tropospheric corrections available in large parts of Europe and North America.

In 2018 we have seen the rise of the BeiDou-3 constellation, with an impressive number of nine launches in one year. With its global coverage and excellent observation quality, BeiDou-3 can be considered an ideal addition to the existing RTX service already delivering corrections for GPS, GLONASS, Galileo, QZSS and BeiDou-2.

In this contribution we show first BeiDou-3 performance results based on the data of Trimble’s global RTX tracking network and using a BeiDou-3 capable prototype implementation of the RTX server and rover software. In addition to analyzing the observation quality of the new BeiDou-3 signals provided by the recently introduced Trimble Alloy reference station receiver, the inherent satellite clock stabilities and RTX orbit accuracies are reviewed. It is shown that using the 19 Beidou-3 MEO and IGSO satellites currently in orbit and healthy, the new constellation already provides substantial improvements in availability and convergence time for RTX users around the world.

ABSTRACT. Geoscience Australia currently runs the role as the IGS Analysis Center Coordinator (IGS ACC). We Combine the orbit and clock solutions submitted by different participating analysis centers into a standard IGS product as one of the main roles of the IGS ACC. With additional GNSS constellations becoming fully operational over the coming years, there is need for an upgrade to the combination software to a more flexible platform which enables combination of multi-GNSS orbit and clock solutions from different analysis centers. Due to the increasing number of satellite types and different capability of each analysis center in modelling each of the satellite systems, an updated weighting strategy is essential. This work presents the current status and future direction of the next version of the IGS ACC combination software currently being developed at Geoscience Australia.

ABSTRACT. A major limitation of the GNSS Precise Point Positioning (PPP) technique is the slow solution convergence time. Tens of minutes are required for the solutions to converge to decimetre-level accuracy even with ambiguity resolution (PPP-AR). This paper analyses two ambiguity resolution methods to provide reliable ambiguity resolution and fast PPP convergence time. They are the partial ambiguity resolution based-LAMBDA method (PAR-Ps) and the iFlex method proposed by Trimble Navigation company. One month of multi-frequency GNSS observations from one CORS station was processed in kinematic mode. The root mean square (RMS) results indicate that the iFlex method outperforms the PAR-Ps method with respect to minimising the position errors of a kinematic test. Although two methods provide a similar horizontal convergence time (one minute), the horizontal error using the PAR-Ps is not stable until the 13-minute mark. This is caused by several sessions with incorrectly-fixed ambiguities. When compared to the PAR-Ps method, the iFlex method has improved the vertical convergence time to about 7 minutes.

ABSTRACT. GNSS technology has revolutionised many aspects of the modern global economy. It provides essential support for everything from precision agriculture, construction and mining, to our understanding of the processes of plate motions, all of which require one thing: precise and accurate position information. Today we are seeing a new generation of GNSS correction services, software and hardware devices enabling cheaper, more compact and truly scalable high-precision GNSS solutions, making the technology accessible to mass-market. At the same time, GNSS and RNSS satellites are also evolving to include next generation augmentation capabilities to improve PNT services. This revolution in precise positioning is helping to realise new applications for example in the automation industry, and to unlock opportunities in new markets. In this contribution, the authors endeavour to encapsulate current developments in GNSS precise positioning in particular the changing landscape of Precise Point Positioning (PPP) services. It includes an efforts at the international level to address standardization and interoperability of PPP services; and speculate on a future where mass-market uptake will be the driving force in the ‘democratisation’ of GNSS precise positioning.

ABSTRACT. For most services areas it is now possible to track most of the major GNSS constellations. This means that the number of available satellites has increased from about 10 SV, for a two hour session to more than 40. This causes a large jump in the computational resources if the Double Difference algorithm is used. This computational load is significantly reduced if undifferenced data is used. The increase in the number of SVs from about 10 to about 40 for a 2 hour session means that there is some solid compensation in the solution degrees of freedom for the algorithm changes. The principal tools for the inter-comparison of data which has instrument and regional effects and processing strategies which involve the use of IGS Ultra Rapid, Rapid and Final products and other non-IGS products such as those generated by commercial houses such as Trimble and Magic-GNS involve the sample mean and standard deviation or variance and graphical visualization techniques. The sample means and variance are particularly sensitive to the mix of the available GNSS constellations and the source of the orbit and clock products. Data showing these dependancies will be presented. It will be demonstrated that the PPP techniques is able to perform at the 10 mm level for 1 to 2 hour sessions.

ABSTRACT. With the recent advent of the ability to extract raw GNSS pseudorange and carrier-phase measurements from smartphones and now dual-frequency, multi-constellation tracking chips, it has become possible to apply Precise Point Positioning (PPP) augmentation to this market, with the goal of providing more accurate positioning for smartphone applications. PPP offers precise positioning results with no additional hardware and can potentially replace the existing metre-level standard positioning solution provided by smartphones.

The magnitude of measurement noise and multipath on the smartphone measurements is in tens of metres as compared to a geodetic-grade low-cost receiver. This impacts the residual RMS for the pseudoranges which is in tens of metres. In order to make full use of the power of PPP processing, smartphone measurements must be carefully analysed and conditioned.

The research focuses on investigating and improving the quality of the raw measurements obtained from conventional smartphone hardware: that have a monopole antenna with poor multipath suppression and irregular gain patterns. Large jumps in the noisy pseudorange measurements, coupled with missing carrier-phase measurements have led to techniques to: 1) model these measurements by filtering out the bad raw measurements; 2) synthesise missing measurements – especially for the second frequency tracked (L5/E5a); 3) model multipath; and 4) filtering of pseudorange measurements with carrier-phase measurements.

Initial results show that single-frequency PPP processing with smartphones have an average horizontal root mean square (rms) error of 60 cm. Though, with dual-frequency multi-GNSS PPP processing, the horizontal rms error was an average of 40 cm. In kinematic data processing, the results were in the metre-level. Measurement analysis provides insight into the quality of the code and phase measurements, trends, outliers, and potentially explains the observed phenomena under user conditions. The conditioning techniques applied allow for increased solution availability and improved solution accuracy. The use of dual-frequency chipsets in smartphones provides the ability to increase positioning accuracy in potential user applications such as location-based services, augmented reality apps and gaming. Future work aims at 1) conducting different types of field tests with new models of chips and phones 2) further customization of the quality control parameters in the YorkU PPP software for data processing 3) measurement noise modelling, and 4) studies of the impact of the improved GNSS positioning on smartphone applications

ABSTRACT. The integration of multi-frequency, multi-GNSS receiver chipsets into smartphone hardware and the accompanying software changes that provide access to raw observation data have generated significant research interest over the past 12 months. Studies to date have focussed on the positioning accuracy of the receiver chipset, testing different positioning techniques and environmental conditions. In all these studies there is an acknowledgement that the contribution of the GNSS antenna to the positioning accuracy has been ignored or treated as a ‘black box’. It is increasingly evident that current receiver chipsets can produce positioning accuracies of ±0.4m (horizontally and vertically), which represents the combined performance of the GNSS antenna and the multi-frequency, multi-GNSS receiver chipset. This paper identifies the GNSS antenna effects impacting the Xiaomi Mi 8 smartphone and quantifies their influence on the positioning accuracy. The GNSS antenna effects considered are the antenna orientation, the smartphone’s wireless communication settings, and human interaction with the antenna. To control the influence of external factors such as the atmosphere, multipath, obstructions, and satellite geometry the Spirent 6425 Record and Playback System (RPS) was used to repetitively playback the raw satellite signals to the Xiaomi Mi8. To ensure the playbacks were not affected by random external signals, each playback took place in an anechoic chamber. Quantifying the individual GNSS antenna effects will result in a model of the overall affect that the GNSS antenna has on the total positioning error budget of the Xiaomi Mi8.

ABSTRACT. This scoping study aims to review the needs of real-time GNSS correction streaming for modern precise positioning (PP) users that will enable existing industries to improve productivity, efficiency, safety and assist in decision making, as well as facilitate the access and adoption of PP technologies in wide range of new applications, such as intelligent transport, autonomous vehicles and Industrial Internet of Things (IoT). While, the Network Transport of RTCM via Internet Protocol (NTRIP) has been the standard data transmission protocol for the current PP applications, several challenges have been identified, including the efficiency and scalability needed to handle the expected volume of modern mass-market users, the ability to effectively handle the evolving GNSS data and correction message types and formats and additional features needed to benefit CORS network operation and provide highly available and dependable services.

Multiple open standard modern data transmission protocols, including MQTT, AMQP, CoAP and more, have been evaluated against the user requirements, including scalability, efficiency, security and interoperability. Specific protocol features have also been evaluated for improving GNSS data and correction services. For example, guaranteed service delivery for GNSS data archives from real-time streaming, data retain to minimize unnecessary data packet transmission (repeated slow varying parameters) and flexible and customized correction messages.

ABSTRACT. NTRIP has been the current standard in GNSS data transmission via the internet for high precision applications with the ability to handle hundreds of CORS stations and up to few thousands of concurrent users. However, it will be challenging to meet the rapid growth in demand from the advances in sensing and communication technologies. New generation high precision GNSS hardware are increasingly capable and affordable for large scale deployment, while new wireless communication technologies enables real-time data transmission at environments that are currently impractical to achieve (long-range, low power consumption and mesh topology). These will accelerate the precise positioning adoption in the industrial, scientific and potentially the consumer markets.

This study proposes a highly available, scalable, reliable and efficient GNSS data transmission service with MQTT protocol with cloud services. MQTT broker clustering with load balancer offers a highly available and scalable backbone for the services, while auto-scaling will meet the dynamic demand of mass-market users. Additional reliability can be achieved with MQTT bridge connecting multiple clusters with hybrid-cloud architecture. MQTT topic hierarchy offers efficient data transmission for users on legacy GPS-only equipment or new generation multi-GNSS receivers. An HTTP server agent has also been developed that receives NTRIP connection and forwards to the MQTT backbone.

Experimental testing with MQTT broker clustering has been conducted to evaluate performance with different service levels (QoS) under various loads. Additionally, latency and various other parameters have been analysed.

ABSTRACT. LTCOL Robin Smith SO1 Robotic and Autonomous Systems Future Land Warfare Branch Army Headquarters (Australia)

ABSTRACT. GPCAPT Mal Hurman Air Force Reserve Defence Space Position Navigation and Timing

ABSTRACT.  

Speaker Biography

Group Captain Jerome Reid is Air Force’s designated disruptor, currently posted as one of the two Directors of Plan Jericho, also known as the Jericho Twins.

Jerome has enjoyed a diverse career across a number of work environments, most often in positions that were underpinned by a focus on enterprise level transformations, capability innovations, people development and organisational change. Until 2016 Jerome was an Australian Army Infantry Officer and in that capacity has led teams in operational planning, combat operations, disaster relief and other humanitarian missions. Jerome also holds a secondary specialisation in military industrial relations and has led significant remuneration, industrial relations, as well as whole of workforce system innovations and reforms in the Australian Defence Force.

Jerome was appointed to his current role in the Royal Australian Air Force to bring his transformation experience and expertise into Plan Jericho, which is the Chief of Air Force’s seminal capability transformational project. Jerome’s role on Jericho is to focus on ‘how to think about complex problems’ and design and deliver Air Force’s internal disruption capability through innovation. Jerome rates Plan Jericho as the best job he has ever had in the military.