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The application of GPS in bridge monitoring aims to determine accurately and precisely the response of the deck and towers of the bridge, and estimate the main response characteristics (amplitude, and modal frequencies). The main requirement of GPS monitoring is a high level of accuracy and availability of fixed solutions, which ensure the reliable operation of GPS and result in the precise estimation of the bridge’s response. However, the derived GPS time series of bridge monitoring can be contaminated by noise, due to the performance of the GPS satellite(s), the geometry of the GPS satellite constellation and the potential obstructions due to the bridge elements, which can even lead to GPS solution of poor accuracy and/or precision and result in reduced efficiency of the performance of the GPS monitoring. This study investigates the potential contribution of other GNSS constellations for a more robust and reliable displacement time series solution, derived from multi-GNSS records. More specifically, a novel method is developed to derive the optimal combination of GNSS records to determine the GNSS displacement time series based on checks of parameters which reflect the geometry of the satellite constellation and the quality of the GNSS satellites signals. The method is applied in monitoring of the Severn Suspension Bridge, in the UK, and it is revealed the enhancement in the GNSS monitoring performance of the bridge response for specific time-intervals for various locations on the bridge’s support towers, suspension cables and deck.

The CoDRIVE solution builds on R&D in the development of connected and autonomous vehicles (CAVs). The mainstay of the system is a low-cost GNSS receiver integrated with a MEMS grade IMU powered with CoDRIVE algorithms and high precision data processing software. The solution integrates RFID (radio-frequency identification) localisation information derived from tags installed in the roads around the University of Nottingham. This aids the positioning solution by correcting the long-term drift of inertial navigation technology in the absence of GNSS. The solution is informed of obscuration of GNSS through city models of skyview and elevation masks derived from 360-degree photography. The results show that predictive intelligence of the denial of GNSS and RFID aiding realises significant benefits compared to the inertial only solution. According to the validation, inertial only solutions drift over time, with an overall RMS accuracy over a 300 metres section of GNSS outage of 10 to 20 metres. After deploying the RFID tags on the road, experiments show that the RFID aided algorithm is able to constrain the maximum error to within 3.76 metres, and with 93.9% of points constrained to 2 metres accuracy overall.

Navigational error accounts for half of the accidents and serious incidents in close to shore maritime transport in Norway predominantly due to the rapidly changing weather conditions and the dangerous nature of the narrow inshore waters found along the Norwegian coast. This creates a dependence on Differential Global Positioning System (DGPS) use and any disruption to this service can lead to an increased accident rate. The aim of this paper is to research the jamming vulnerability of existing maritime receivers and to understand if an upgrade to a multi-constellation or multi-frequency receiver would improve system resilience. The novelty of this work is a comparison of jamming resilience between different combinations of multiple constellations (GPS and Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS)) and multi-frequency Global Navigation Satellite System (GNSS) signals. This paper presents results from GNSS jamming trials conducted in the northern part of Norway, confirming previous research and indicating that typical maritime GPS receivers are easy to jam and may produce erroneous positional information. Results demonstrate that the single frequency multi-constellation receivers offer better jamming resilience than multi-frequency (L1 + L2) GPS receivers. Further, the GLONASS constellation demonstrated a better resilience than GPS. Results demonstrate a known correlation between GPS L1 and L2 frequencies, as well as a probable over-dependence on GPS for signal acquisition, meaning that no signal can be received without GPS L1 present. With these limitations in mind, the authors suggest that the most economic update to the single frequency GPS receivers, currently used for maritime applications, should be multi-constellation GPS + GLONASS receivers. This solution is cheaper and it also offer better jamming resistance for close to shore navigation than dual frequency receivers.

Global Navigation Satellite Systems (GNSS) is the most commonly used positioning technology for many Location Based Services (LBS) including navigation. However, GNSS applications are limited to outdoors as GNSS signals can get blocked and attenuated inside or between buildings, making positioning unreliable, inaccurate or impossible. Blockage of GNSS signals may result in the lack of availability of the minimum of four satellites in-view at each epoch, for a single constellation GNSS positioning, and consequently, lead to a failure in the continuity of the positioning service. This is a particularly common issue in urban canyon and indoors. This paper proposes and implements a framework to handle this challenge by virtually distribute the antenna in space and time and accumulate the measurements while adding some unknowns to solve the synchronization and the position solution. To test the proposed technique, Virtual Spatial Diversity Antenna (VSDA), raw GNSS measurements are captured using an Android 7.1.1. running smartphone over the period of forty-seven minutes. Then the observations are accumulated until the number of measurements outcounts the number of unknown, i.e. three position components plus the number of epochs. The results of the GPS-only measurements for a relatively limited period of 47 minutes, where satellite geometry may not significantly change, prove the feasibility of solving position solution in presence of fewer than four satellites at each epoch using VSDA scheme, and achieving the horizontal and vertical accuracy of 47.16 m and 68.45m, respectively.

Wireless communication signals have become popular alternatives for indoor positioning and navigation due to lack of navigation satellite signals in such environments. The signal characteristics determine the method used for positioning as well as the positioning accuracy. Ultra-wideband (UWB) signals, with a typical bandwidth of over 1 GHz, overcome multipath problems in complicated environments. Hence, potentially achieves centimetre-level ranging accuracy in open areas. However, signals can be disrupted when placed in environments with obstructions and cause large ranging errors. This paper proposes a ranging measurement quality indicator (RQI) which detects the UWB measurement quality based on the received signal strength pattern. With a detection validity of more than 83%, the RQI is then implemented in a ranging-based collaborative positioning system. The relative constraint of the collaborative network is adjusted adaptively according to the detected RQI. The proposed detection and positioning algorithm improves positioning accuracy by 80% compared to non-adaptive collaborative positioning.

As the demands on terrestrial transport systems increase, there is a growing need for greater efficiencies. More intelligent mobility and ultimately autonomous transport assets will deliver these efficiencies through the evolution of cooperative intelligent transport system (C-ITS) technology. Central to this evolution will be the capability to accurately and precisely position assets within their environment and relative to each other to predefined and regulated standards.\ud \ud The core of modern positioning and navigation methods are the global navigation satellite systems (GNSS) (e.g. GPS, Galileo, GLONASS and BeiDou). These systems rely on line of sight radio frequency signals, which are vulnerable to obstruction and/or interference (e.g. multipath and/or non-line of sight reception). As a result, the position accuracy is degraded and therefore GNSS would greatly benefit from a priori intelligence that predicts where and when obscuration or interference will occur. Similarly, a real time assessment of where and when GNSS signal reception will be restored and the location of the satellites in the sky will aid in restoring satellite lock. This paper describes a computer vision system that utilises 360o images to derive a priori intelligence to predict changes in the environment that may threaten position and navigation integrity.

GPS is the positioning tool of choice for a wide variety of applications where accurate (cm level or less) positions are required. However GPS is susceptible to a variety of errors that degrade both the quality of the position solution and the availability of these solutions. The contribution of additional observations from other GNSS systems may improve the quality of the positioning solution. This study investigates the contribution of the GLONASS and BeiDou systems and the potential improvement to the precision achieved compared to positioning using GPS only measurements. Furthermore, it is investigated whether the combination of the satellite systems can limit the noise level of the GPS-only solution. A series of zero-baseline measurements, of 1 Hz sampling rate, were recorded with different types of pairs of receivers over 12 consecutive days in the UK and in China simultaneously. The novel part in this study is comparing the simultaneous GNSS real measurements recorded in the UK and China. Moreover, the correlation between the geometry and positional precision was investigated. The results indicate an improvement in a multi-GNSS combined solution compared to the GPS-only solution, especially when the GPS-only solution derives from weak satellite geometry, or the GPS-only solution is not available. Furthermore, all the outliers due to poor satellite coverage with the individual solutions are limited and their precision is improved, agreeing also with the improvement in the mean of the GDOP, i.e. the mean GDOP was improved from 3.0 for the GPS only solution to 1.8 for the combined solution. However, the combined positioning did not show significant positional improvement when GPS has a good geometry and availability.

This work focuses on the performances of Locata technology in single point positioning using different firmware versions (v2.0 and v4.2). The main difference is that the Locata transmitters with firmware v2.0 are single frequency, whereas in the v4.2, they are dual frequency. The performance of the different firmware versions has been measured in different environments including an urban canyon-like environment and a more open environment on the roof of the Nottingham Geospatial Building. The results obtained with firmware v4.2 show that with more available signals, cycle slips can be more easily detected, together with the improvement of the detection of multipath fading on the received signal. As a result, the noise level on the carrier phase measurements recorded with firmware v4.2 is equal on average to a third of the level of noise on the measurements recorded with firmware v2.0. In addition, with either firmware, the accuracy of the position is at the sub-centimeter level on the East and North coordinates. The Up coordinate accuracy is generally less accurate and more sensitive to the geometry of the network in our experiments. We then show the importance of the geometry of the Locata network on the accuracy of Locata positioning system through the demonstration of the relationship between the dilution of precision value and the confidence ellipse. We also demonstrate that the model of the noise on the Locata coordinates is a white Gaussian noise with the help of the autocorrelation function. To some extent, this technique can help to detect whether the Wi-Fi technology is interfering with the Locata technology and degrades the positioning accuracy.

Around 90% of trade and good are transported by sea. In the same time, navigational error accounts for half of the accidents and serious incidents worldwide. These errors have increased significantly since the introduction of GPS and ECDIS (Electronic Chart Display and Information System) on most ships (1995-2002). While there is no direct evidence, previous research [1,2] has suggested that navigators’ over-reliance on GPS could be a cause. Norwegian Coastal Administration provides a network of 12 Differential GPS (DGPS) stations along the coast to support navigation in dangerously narrow fjords, prone to a rapid weather changes. Any disruption to this service or GPS in general, will also affect the AIS service as it relies on GPS to provide both the position and the synchronisation time. With commercial jammers are available online for less than a hundred dollars [3], it is a very realistic security and safety threat. In the previous research [4] authors demonstrated, in live trials, that in the most common L1 jamming scenario the use of multi constellations offers better jamming resilience than the use of multiple frequencies. Results demonstrate known correlation between GPS L1 and L2 frequency, and possibility of over-dependence on GPS for signal acquisition, meaning that no signal can be received without GPS L1 signal being present. This paper describes a further research with the aim to understand the ability of the modern GNSS front ends to mitigate GPS L1 frequency based jamming, verify GPS over-dependence and to identify implication of those for the close to shore maritime navigation. The conducted consisted of laboratory and live trials, with the multiple modern GNSS front-ends tested. Former have been conduced using SPIRENT GSS9000 simulator and dedicated interference signal generator. Jamming simulation has been based on previously published trials [4] and included: * a continuous wave (CW) at 1575.42MHz (GPS L1 centre frequency) with varied spread and power; * a frequency modulated CW (MCW) swept over L1 and G1 frequencies. Results of the simulation have been verified by the life trials, conducted in the fjords in southern Norway and using GPS L1 frequency centred jammer. Initial results show that response to jamming is dependent on the front end type. The result, from laboratory and live trial, will be used to improve the understanding the jamming effect on the different vessels and GNSS solutions. This will be used in the further research, including large volume AIS pattern analysis. [1] Grant, A., Williams, P. and Basker, S. (2010): “GPS Jamming and its impact on maritime safety” in Port Technology International, vol. 46, pp. 39-41 [2] Boyes, H. A. (2013): “Maritime Cyber Security - Securing the Digital Seaways” (Sector Publications, 2013), Resilience, Security & Risk in Transport, Sector Publications, pp. 56-63, DOI: 10.1049/PERRSR3E_ch9 IET Digital Library [3] Mitch, R., Dougherty, R., Psiaki, M., Powell, S., O`Hanlon, B., Bhatti, J. and Humphreys, T. (2011): “Signal characteristics of Civil GPS Jammers” in Proceedings of ION GNSS 2011, pp. 20-23 [4] Oeystein Glomsvoll and Lukasz K Bonenberg (2016): "GNSS Jamming Resilience for Close to Shore Navigation in the Northern Sea", Journal of Navigation [5] P. Craven, R. Wong, N. Fedora, P. Crampton, (2013): "Studying the Effect of Interference on GNSS Signals" , Institute of NavigationInternational Technical Meeting 2013, (ITM 2013), San Diego, California, USA, 28 – 30 January 2013 [6] Borio, D.; O'Driscoll, C. and Fortuny, J., (2013): "Jammer impact on Galileo and GPS receivers," International Conference on Localization and GNSS (ICL-GNSS), 25-27 June 2013 pp. 1-,6, doi: 10.1109/ICL-GNSS.2013.6577265. [7] Erik Axell, Fredrik M. Eklof, Peter Johansson, Mikael Alexandersson and Dennis M. Akos, (2015): "Jamming Detection in GNSS Receivers: Performance Evaluation of Field Trials", NAVIGATION : Journal of The Institute of Navigation, Vol. 62

With the rise of large city and the need of large civil engineering structures and city planning, surveying industry improves continuously their instruments/software in order to get cm accuracy position anywhere. Moreover, since the boom of mobile phones in the late 90s, location has become very valuable information for security, emergency and commercial applications. Depending of the application, the location technologies vary based on the accuracy of the location and the price of the system, which delivers the location information to the user. For outdoor applications, Global Navigation Satellite System is the main candidate, whereas if the user/mobile node is indoors or in a narrow street other technologies will be preferred such as the ones based on Wi-Fi or radio-frequency signal.This chapter provides an overview of different positioning technologies used in geo-location together with their limits/advantages. This chapter studies also a number of algorithms developed to estimate the position coordinates of a static or mobile user or target.

2012 International Conference on Indoor Positioning and Indoor Navigation, IPIN 2012 - Conference Proceedings 2012, Article number 6418893 An integrated positioning solution termed 'collaborative positioning' employs multiple location sensors with different accuracy on different platforms for sharing of their absolute and relative localizations. Typical application scenarios are dismounted soldiers, swarms of UAV's, team of robots, emergency crews and first responders. The stakeholders of the solution (i.e., mobile sensors, users, fixed stations and external databases) are involved in an iterative algorithm to estimate or improve the accuracy of each node's position based on statistical models. This paper studies the challenges to realize a public and low-cost solution, based on mass users of multiple-sensor platforms. For the investigation field experiments revolved around the concept of collaborative navigation, and partially indoor navigation. For this purpose different sensor platforms have been fitted with similar type of sensors, such as geodetic and low-cost high-sensitivity GNSS receivers, tactical grade IMU's, MEMS-based IMU's, miscellaneous sensors, including magnetometers, barometric pressure and step sensors, as well as image sensors, such as digital cameras and Flash LiDAR, and ultra-wide band (UWB) receivers. The employed platforms in the tests include a train on a building roof, mobile mapping vans, a personal navigator and a foot tracker unit. In terms of the tests, the data from the different platforms are recorded simultaneously. Several field experiments conducted in a week at the University of Nottingham are described and investigated in the paper. The personal navigator and a foot tracker unit moved on the building roof, then trough the building down to where it logged data simultaneously with the vans, all of them moving together and relative to each other. The platforms then logged data simultaneously covering various accelerations, dynamics, etc. over longer trajectories. Promising preliminary results of the field experiments showed that a positioning accuracy on the few meter level can be achieved for the navigation of the different platforms. © 2012 IEEE.

GNSS has become one of the most wide- spread measurement technologies, allowing cm-level positioning accuracy using RTK or Network RTK. Unfortunately, the system’s major drawbacks are the requirement for a clear view of the sky and accu- racy dependent on the geometric distribution of the satellites, not only varying throughout the day but also prone to location specific problems. With wide- spread utilisation of GNSS for monitoring of man- made structures and other civil engineering tasks, such shortcomings can be critical. One of possible solution is the deployment of a sup- porting system, such as Locata – a terrestrial posi- tioning technology, which mitigates the need for a clear view of the sky and provides system integrity control. This paper, part of the proposed integration feasibil- ity study, presents Locata performance indoors, its capacity and mitigation methods.

RailSat aims to use Global Navigation Satellite System (GNSS) to monitor and maintain railway assets and its surrounding environment by railway asset owners and/or other relevant stakeholders. The rail sector is looking for continuous monitoring solutions which have no impact on the train service, both wayside (track bound) and onboard (train bound), which require accurate positioning while travelling at high speeds (>120kmh). This paper focuses on the combination of positioning data from traditional GNSS/INS system with processed LIDAR point cloud and discusses real-life results from the Snake Pass, Peak District, England. Data have been collected using a dedicated multisensory van but the nature of the road allows us to draw conclusions relevant to the rail industry. This paper discusses the proposed deployment of a mobile LiDAR monitoring system consisting of a set of laser scanners and a navigation component. While the LIDAR component is capable of centimetre accuracy, it is limited by the navigation accuracy, predominantly affected by the difficult railway environment, frequent multipath and NLOS interference combined with a loss of signal next to the monitoring structures itself (bridges, cuttings, tunnels, embankments etc.), making precise positioning the biggest challenge. The proposed navigation system combines IMU positioning system with a computer vision system capable of localisation using features in the natural environment. This paper outlines the combination of the proposed navigation system with the LIDAR’s information, which provides two ways of correcting navigation trajectory in post-processing.