Supergeo announced that SuperGIS Server 3.1a Value Edition and Standard Edition are officially launched globally.
According to the announcement, SuperGIS Server is designed for enabling organizations to create, manage, integrate and publish the various types of GIS services. Through SuperGIS Server, spatial data and spatial images of all types as well as GIS functions can be applied as GIS services in desktop, mobile and web applications over the internet to assist enterprises in building ideal workflow and improving productivity.
The newest SuperGIS Server 3.1a mainly adds geoprocessing service publishing functions and enhances the efficiency of map cache tools. Besides the functions in Value edition, SuperGIS Server 3.1a Standard Edition additionally provides developers with Mobile SDK to customize mobile applications which can access SuperGIS Server services and meet various requirements.
Several weeks ago I attended the Esri Federal Users’ Conference in D.C. Not surprisingly, the conference was opened by Jack Dangermond, founder and president of Esri. As with most Esri conferences, there is too much to cover in this short column, so I’m providing my highlights.
Jack opened the conference by presenting the Esri “Making a Difference” award. This year it was given to the Army’s Arlington National Cemetery (ANC) and “make a difference” they did! Shown here accepting the award from Jack is Kathryn Condon, the Executive Director and Major Nicholas Miller, the Chief Information Officer (left).
Several years ago you may remember the scandalous news reports of very poor management and almost total lack of accountability at the ANC. Countless burial plots were misrecorded, finding a burial location for visiting family members was tedious, and some tombstones were even found dumped in a nearby stream. Tracking and management was accomplished via hand-typed index cards and colored pencil annotation of paper maps. We GISPs knew instantly that GIS was the answer and fortunately so did the Army. Their solution was thorough and elegant.
The Army, working with GIS, Inc., spent several months collecting more than 250,000 point locations of grave markers across the 624-acre cemetery. They used Trimble handheld GPS units to record each tombstone to an accuracy of three inches. Additionally, a digital photo of each tombstone was taken and recorded in the database. The result is an online system called ANC Explorer, which displays GIS maps, aerial imagery and digital photos of ANC that visitors can use to navigate the cemetery. Additionally, family members who can’t visit the cemetery in person can do a virtual search and tour.
Jack’s Vision
Jack outlined his long-standing vision of where GIS is and where it is heading. Much of his vision in the past was just that, a “vision.” However, reality has caught up. He spoke of the turning point brought about by cloud computing. He used the term “GIS as a platform” where software such as ArcGIS Online is mashed with other systems to create a pervasive geographic system that enables countless applications. Web maps point back to authoritative data sources rather than carrying the baggage of large local databases. Lightweight, agile applications are extendable, interoperable and permit easy collaboration. As part of this, the emphasis is on web maps as the new medium. He stated that web maps are simple, powerful, and cost effective for collaboration and integration. ArcGIS is the platform enabling this with three components: applications, content, and infrastructure.
To make all this happen, Esri is spending considerable time and effort not only on the technology, but to assemble extensive authoritative content. This is the big difference between Esri and Google. Google has changed how we all view computer mapping, but as many of us have learned over the years, Google is not necessarily an authoritative source. By its own admission, Google’s purpose is to attract users and drive them to advertising. They have no desire to become the world’s GIS expert. Esri on the other hand is working toward that goal. One example supporting this effort is Esri’s Landscape Analyst, which is being released this month. Similar to Community Analyst, designers can develop maps based on a variety of authoritative public data sets related to land use, land cover, pipelines, transmission lines, imagery, and many other features. The interesting aspect of Landscape Analyst is that more than 30 selected data sets can be used, downloaded, and incorporated into local applications.
Another announcement that caused a buzz was the free availability of DigitalGlobe World Imagery. The new update includes 30-cm imagery for the continental United States down to 1:1,000 scale, and 60-cm imagery for large parts of Western Europe down to 1:2,000 scale. Throughout the year, Esri and DigitalGlobe will grow the coverage with more than 100 million square kilometers of updated high-quality imagery, making it one of the most detailed free basemap services available.
CityEngine
For those of you interested in 3D GIS, CAD, BIM models, Voxels and visualization, CityEngine seems to blur the lines between each and merits a serious look. CityEngine was demonstrated during the plenary session, and is clearly a very fast and easy-to-use 3D modeling environment. It combines rapid 3D model creation from 2d GIS data, similar to Google SketchUp with serious database connectivity in a procedural-based environment.
Although I personally haven’t worked with CityEngine, the demos are impressive. See a video demo. CityEngine integrates standard file formats, including Collada, RenderMan, Google Earth, SketchUp, Wavefront, 3DS, Autodesk FBX, and WebGL. The CityEngine models can be viewed in ArcScene and WebScene. An interesting capability that could be very valuable for public meetings is a slider bar that can show inside/outside or before/after images.
One word of caution that I learned working with first responders is the use of textures or cloned images to create 3D models. Previous work I did with Pictometry and PLW Modelworks highlighted the difference between a representation of a 3D scene and use of actual geo-registered imagery. PLW builds 3D models that are “photorealistic” and “photo-accurate.” The models are built from imagery and each building is draped on each side with the actual measurable image of the building. As you can imagine, it’s important that a window shown 5 feet above ground is actually there and not just a graphic. If occlusions block some portion of the image, PLW makes no attempt to fake the image. It instead shows a no-data area that looks like a black shadow.
Note this example. The “shadow” is really a no-data location of the image.
Social Media
A pervasive topic that was part of numerous sessions and Expo exhibitors was social media and big data. The integration of this real-time data with GIS data and analytics is proving to enhance both, and its use is growing. There was a powerful example shown in the plenary session using Topsy technology. Topsy uses complex algorithms to do expert searches on thousands of tweets to discover information based on keywords or terms. The search ranks results based on topical focus and geography. Since only 1 percent of tweets are explicitly geotagged, Topsy developed machine learning methods to infer an author’s location, using features such as regular references to landmarks or events. By doing so, it claims to have high-confidence geographic information for more than 90 percent of tweets. The company demonstrated the benefit of plotting real-time tweets about power outages as a second, validating source of data during Hurricane Sandy.
Several exhibitors showed social media exploitation tools that were equally impressive. TerraGo demonstrated GeoXRAY, a system that combines GIS data with social media discovery and exploitation tools, brought together into a GeoPDF that can be used off-line in local collaborations by non-GIS users.
Other exhibitors were using social media for intelligence applications, financial analysis, and business and marketing applications, with a dizzying array of claims. My personal observation is that the social media environment is like the “Wild west.” Similar to the early days of GIS, there are competing products, repackaged data, and capabilities with overlapping systems. It will take a while to sort it out, but this is too important a topic to take lightly. Look for more information in future columns as I get educated.
The California Technology Agency has launched the California GeoPortal, an interactive and user-friendly gateway to thousands of geographic data sources around the country.
“California’s new GeoPortal organizes important geographic data and makes it more accessible and useful,” said Secretary Carlos Ramos. “This innovation increases government transparency, boosts efficiency and saves the State money.”
According to the announcement, the California GeoPortal helps find solutions to real-world problems such as locating a new business or helping choose a new place to live. The GeoPortal gathers thousands of data sources such as demographics, environmental hazards, school information and transportation, and makes the information more accessible and useful. The GeoPortal strengthens these databases by combining information and making it customizable.
“For the first time in our history, California is taking a statewide approach to sharing data and mapping it to provide a visual location based view for our stakeholders – both public and private industry,” said Scott Gregory, California’s Geographic Information Officer. “By making these diverse resources accessible and relevant, it becomes a very efficient and powerful decision making tool for all Californians.”
“The GeoPortal is a groundbreaking tool enhancing collaboration and data sharing among the public and private sector,” said Carl Guardino, the Chief Executive Officer of the Silicon Valley Leadership Group. “Business will have accurate and relevant data at their fingertips, supporting their decisions to help grow California’s economy.”
The announcement stated that California’s GeoPortal is a comprehensive catalog of thousands of data sources from federal, state, county, city, tribal and education geographic resources. Users can access the GeoPortal from the web without having to login to another system, streamlining access to government derived and developed data.
“The ability to share geospatial data through a single public source will be a tremendous benefit to the academic institutions in California,” said Dr. Shawna Dark, Department of Geography Chair, California State University, Northridge.
The GeoPortal is a service offering by the California Technology Agency to state and local agencies and departments at no cost. It is a tool to be leveraged by organizations to catalog and manage their geographic data resources. Organizations will be able to register their geographic data content on the GeoPortal and securely manage their information. It has a robust set of management tools that allow organizations to edit, upload and maintain geographic information. The end result is a more comprehensive and authoritative data resource for geographic data in California.
For a video introduction to the California GeoPortal, visit here.
The USGS announced it is expanding the involvement of volunteers to enhance data collection about structures for The National Map.
This program, known as The National Map Corps, focuses on encouraging citizens to collect data relating to structures by both adding new features and/or correcting existing data within The National Map database. These structures can include schools, hospitals, post offices, police stations and other important public places.
According to the announcement, collaborative pilot projects in Colorado were recently used to test the concept of crowd-sourcing. While the project is on-going, early indications point to positive results and show the success of using TNMC volunteers to enhance data sets.
The USGS reported that over a trial period of ten months, 143 volunteers collected, improved, or deleted data on more than 6,400 structures in Colorado. The volunteers’ actions were accurate and exceeded USGS quality standards. In the Colorado pilot project the volunteer-collected data showed an improvement of approximately 25 percent in both location and attribute accuracy for existing data points. Completeness, or the extent to which all appropriate features were identified and recorded, was nearly perfect.
The significant results of the Colorado pilot have led to a phased, nation-wide expansion of the crowd-sourcing /volunteer project. The states in the first expansion of TNMC are: Arkansas, Alaska, Colorado, Delaware, Georgia, Idaho, Maryland, Michigan, Montana, North Dakota, New Jersey, New Mexico, Ohio, Oregon, South Carolina, Utah, Washington, West Virginia
After an evaluation of the quality and procedures of the first group of states, the second set will be made available. Ultimately, by the end of 2013, the third batch of states will complete the expansion of the program.
“The response by volunteers in Colorado exceeded our expectations both in terms of the number of volunteers and the quality of the data they collected”, said Kari Craun, the Director of the USGS National Geospatial Technical Operations Center. “The Volunteered Geographic Information (VGI) community represents a fantastic, untapped resource to assist USGS in maintaining data that are part of The National Map.”
While some familiarity with the area that a volunteer chooses is helpful, one doesn’t have to live near a particular place to contribute. The tools on TNMC website, along with ancillary information available on the Internet, are generally sufficient to edit a distant area.
There have been several instances of crowd-sourced geographic information making significant contributions to research and databases in government, private sector, and non-profit organizations. The goal of the TNMC is to provide data for the nation’s primary federal mapping agency in its effort to provide accurate and authoritative spatial data via the web-based National Map.
The citizen geographers/cartographers who participate in this program will make a significant addition to the USGS’s ability to provide accurate information to the public. Data collected by volunteers become part of TNM Structures dataset which is available to users free of charge.
Without a network of volunteers, the desired information would not be collected this year and the existing data would not be updated. TNMC volunteers perform important work that otherwise will not be accomplished in the foreseeable future.
Becoming a volunteer for TNMC is easy; go to the National Map Corps website to learn more and to sign up as a volunteer. If you have access to the Internet and are willing to dedicate some time to editing map data, we hope you will consider participating!
Esri and Geofeedia announced plans to extend the ArcGIS platform with Geofeedia’s social media tools. Public safety professionals will be able to advantage of these capabilities to accurately integrate, monitor, analyze, and visualize live emergency data as events unfold. Deploying assets and personnel, understanding of events on the ground, adjusting response on the fly, and post-event monitoring are all improved using social media combined with location analytics.
“Geofeedia is an innovator in location-based social media,” says Ryan Lanclos, emergency management manager, Esri. “Both organizations recognized that understanding location provides context and value to social media. Ultimately, this improves meeting mission demands.”
“Esri is an industry leader and provides the ideal enterprise platform to visualize and analyze real-time social media feeds from Geofeedia,” says Phil Harris, CEO of Geofeedia. “Location-based social media data layers from Geofeedia combined with Esri’s technology and vast repository of other layers give public safety officials the best combination of real-time intelligence for response efforts.”
According to the announcement, the real-time data integration, searching and streaming will work across multiple social media platforms including Twitter, Instagram, Flickr, YouTube, and Picasa. Geo-located tweets, photos, and videos can be viewed within the context of digital imagery, street networks, topography, and community base maps. The social data can be mashed up with other information such as public safety assets, city infrastructure, utility networks, hazardous materials, demographic data, and more. Additional dynamic data including weather, automated vehicle location, GPS, and traffic video camera feeds can be combined with social and map data. In addition, people can perform historical social media analysis to identify trends and patterns.
In addition to public safety, professionals in government, national security, healthcare, and insurance will be able to extend the ArcGIS platform by adding intelligence about social conversations. This includes social media sentiment, location, population profile, and temporal and spatial trend analysis. Adding intelligence improves security, crisis response and business continuity, event monitoring, marketing, compliance, and more.
The International GNSS Service (IGS), a worldwide federation of agencies involved in high-precision Global Navigation Satellite System applications, has announced the launch of its Real-Time Service (RTS). The RTS is a global-scale GNSS orbit and clock correction service that enables real‐time precise point positioning (PPP) and related applications requiring access to IGS low latency products.
The RTS is offered in beta as a GPS-only service for the development and testing of applications. The Russian GLONASS is initially provided as an experimental product and will be included within the service before the end of 2013 as the RTS reaches its full operating capability. Other GNSS constellations will be added as they become available.
The RTS is operated as a public service. Users are offered free access through subscription. Interested parties are invited to visit the service’s website.
The IGS is a worldwide federation of more than 200 organizations that operate a cooperative global infrastructure to provide the highest-quality GNSS data products for scientific users. The IGS is a service of the International Association of Geodesy (IAG), one of the associations of the International Union of Geodesy and Geophysics (IUGG). It is also a service of the World Data System of the International Council for Science (ICSU/WDS).
Scientists in Hanoi, Vietnam, send word that on March 27 the four Galileo in-orbit validation satellites were visible at the same time in the sky over that Southeast Asian country for nearly two hours (from 2:15 to 4:00 GMT) while transmitting a valid navigation message.The research team of the NAVIS Centre at Hanoi University of Science and Technology (HUST) successfully computed what they claim is the first Galileo-only position fix in Asia.
Figure 1 depicts the obtained positions are depicted on top of the roof of the NAVIS Centre, where the antenna used to receive the signals is located (latitude = 21°00’16.69” N, Longitude = 105°50’37.90” E, height = 35,2 meters).
Figure 1. Positions obtained by only Galileo E1 Open Service (the antenna is located at the roof of the Ta Quang Buu library building inside HUST campus)
Figure 2 shows the positions of the four Galileo satellites and of 12 GPS satellites at time of acquisition, while Figure 3 reports the acquisition results of the four Galileo IOV satellites.
Figure 2. Skyplot of the satellites of the GPS and Galileo systems at the time of the campaign. The Galileo satellites are PFM (PRN11), FM2 (PRN12), FM3 (PRN19), and FM4 (PRN20).Figure 3. Acquisition results of the four Galileo IOV satellites: PRN 11.Figure 3. Acquisition results of the four Galileo IOV satellites: PRN12.Figure 3. Acquisition results of the four Galileo IOV satellites: PRN19.Figure 3. Acquisition results of the four Galileo IOV satellites: PRN20.
Comparison of the position computed using only Galileo, only GPS or both systems together is also presented in Figure 4. It should be noted that during the campaign, the data demodulation process reports that the Galileo system announces the “navigation data valid” status for PFM and FM3, meanwhile the “working without guarantee” for FM2 and FM4.
Figure 4. Position computed when using GPS only, Galileo only, or GPS+Galileo
The NAVIS Centre, located at the Hanoi University of Science and Technology in Hanoi, Vietnam, was established with a project co-funded by the European Union and collaborates with European and Asian partners on research and development of satellite navigation technology in Southeast Asia. This report was made by Dr. Ta Hai Tung, director of the NAVIS Centre, and Prof. Gustavo Belforte, co-director.
eLORAN Initial Operational Capability at the Port of Dover
An overview of the work of the General Lighthouse Authorities of the United Kingdom and Ireland on the implementation of Enhanced Loran Initial Operational Capability (IOC) in the waters around Great Britain. eLoran is the latest in the longstanding and proven series of low-frequency, LOng-RAnge Navigation systems. It evolved from Loran-C in response to the 2001 Volpe Report on GPS vulnerability. It vastly improves upon previous Loran systems with updated equipment, signals, and operating procedures.
By Paul Williams and Chris Hargreaves
GPS/GNSS is everywhere! It is used in many ship’s systems (Figure 1), but it is vulnerable to interference both intentional and unintentional.
Its output is displayed on the electronic chart display and information system; is transmitted to other vessels using the Automatic Identification System (AIS); is used to calibrate the gyro compass; is used in the radar; is connected to the digital selective calling, its reported position transmitted at the push of the emergency button for search-and-rescue; is in the vessel data recorder, the dynamic positioning system, surveying equipment, the ship’s entertainment system for aiming the satellite dish; and it even synchronizes the ship’s clocks!
28 days worth of ship-traffic data for the Strait of Dover.
GNSS is also used in marine Aids-to-Navigation (AtoN) provision, for deploying buoys and lights, AIS transponders, and AtoN position monitoring, and its precise timing capabilities are used to synchronise the lights along an approach channel to improve conspicuity.
GNSS (effectively GPS) has become the primary Aid-to-Navigation (AtoN) used by all professional and most other mariners. The vulnerability of GNSS to space weather and interference (unintentional and criminal jamming) means that a backup system is needed to achieve resilient Position, Navigation, and Timing (PNT) for e-Navigation. Though the probability of losing GNSS may be low, the consequential impact could be very high, and maintaining an appropriate balance of physical and radionavigation AtoNs is vital for e-Navigation.
Figure 1. GPS is used in many ship’s systems.
The International Maritime Organisation seeks to develop a strategic vision for e-Navigation, integrating existing and new navigational tools in an all-embracing system, contributing to enhanced navigational safety and environmental protection, while reducing the burden on the navigator. One of IMO’s requirements for e-Navigation is that it should be resilient — robust, reliable and dependable.
The General Lighthouse Authorities of the United Kingdom and Ireland (GLAs) have the statutory responsibility to provide marine AtoNs around the coast of England, Wales, Ireland, and Scotland. It has become clear over recent years that if the GLA chose to implement eLoran, it could rationalize its physical AtoN infrastructure, removing some lights and other physical aids, and on balance actually reduce costs by implementing eLoran. Indeed, compared to other possible resilient PNT options such as GNSS hardening, radar absolute positioning, increasing physical AtoN provision, eLoran would save the GLAs £25.6M over a nominal system lifespan of 10 years from the introduction of e-Navigation services in 2018 to 2028.
Not So Old-Fashioned. How does the new eLoran differ from the old, outdated, Loran-C system? The core signal of eLoran is pretty much the same as Loran-C, but tolerances have been tightened up. Things like carrier zero crossing points, half-cycle peaks, ECDs, transmission timing, signal power, signal availability, power supply resilience have all been upgraded, taking advantage of improvements in technology allowing us to better appease the so-called four horsemen of navigation: accuracy, availability, continuity, and integrity.
SAM control is a thing of the past, and eLoran transmitters are synchronised directly to UTC. This means that their times of transmission can be predicted. Having stations independently synchronised to UTC means that the mariner no longer has to rely on old-fashioned hyperbolic navigation. Charts with hyperbolic lines of position on them are also a thing of the past. A modern eLoran receiver works just like a GPS receiver, employing signals from all available transmitters in its position solution. With GPS those transmitters are moving in space; in eLoran the transmitters are fixed onto the surface of the Earth.
Reelektronika LORADD receiver, only 3 centimeters tall.
Modern receivers are small (photo). They use off-the-shelf, high-performance processors, and the receiver is written in software, allowing a lot of flexibility.
Three transmitters are sufficient to give you position; four or preferably five signals are better for integrity. But for timing and frequency applications you only need one transmitter. The Anthorn station in the UK can cover the entire UK and Ireland with a radio signal that has stability enough to satisfy the Stratum 1 frequency source requirement for steering the clocks of telecom networks, and Anthorn has not even been upgraded to full eLoran standard yet!
One of the big differences between Loran-C and eLoran is that eLoran now has a data channel. Some of the Loran pulses of each pulse group are modulated so that data can be sent over the 100kHz signal. This allows service providers to send integrity alerts, and application-specific data, like UTC time, and differential-Loran (DLoran) and DGPS corrections. In Europe this is implemented by the already internationally standardised Eurofix system.
A parallel can be drawn with GPS signals, which contain a navigation component (pseudorandom noise code and/or carrier phase) and modulated data. Some options for data channel technology are still evolving with 1500 bits per second demonstrated, and 3000 bps possible. That may not sound very much to salt-of-the-earth communications engineers, but for Loran it’s pretty impressive, especially when you consider prototype attempts at Loran data communications in the past have been limited to 30 to 250 bps.
Maritime Applications Services
How do we apply eLoran to something like the maritime application of port approach? It is important to remember that the receiver operates by measuring how long it takes a groundwave radio signal to travel over the surface of the earth. An eLoran receiver assumes that the world is made entirely of seawater, for which it has a very accurate propagation model built in. The receiver does not, and indeed cannot, know about any land along the propagation path; and land slows the signal down, perhaps by as much as a few microseconds, over typical propagation distances.
So the service provider must survey the effects of the land masses in the area of coverage. The Additional Secondary Factors (ASFs) of all the stations across the proposed service area are therefore mapped. The ASF survey is a once-and-for-all task, but it needs to be done and the ASFs published. In the old days, hyperbolic lines would be “grid warped,” or tables would be published on paper for the navigator to enter values manually. But with modern eLoran receivers containing large amounts of memory, quite detailed ASF maps can be stored in the mariner’s receiver.
ASFs depend on the electrical conductivity of the surface over which the eLoran signal travels. The conductivity changes with the constitution and moisture content of the earth. This means that the ASF along a path varies over a period of time —perhaps by as much as a few hundred nanoseconds over a year. Because the ASFs in a receiver are fixed, a method is needed to correct for this temporal ASF variation. In order to monitor this variation, a reference station is installed close to the harbor or point of use of the eLoran service. This DLoran reference station measures the temporal changes in the signals’ arrival times due to changing ASFs, transmitter variations, and weather effects.
The phrase “reference station” conjures up images of expensive buildings, amenities, and hordes of personnel and associated support services. However, a DLoran reference station is a small box sitting in the corner of a room connected to a small eLoran receive antenna on the roof, and to the Internet. It sends differential corrections over the Internet to an eLoran transmitter, which then broadcasts them to the mariner’s receiver over the Loran Data Channel, for example Eurofix.
Note that a DLoran reference station does not transmit a radio signal. It does not need a transmitter itself; it uses the Internet and the eLoran signal to disseminate its real time data. The mariner uses the same eLoran receiver to receive both the navigation signal AND the differential corrections.
So the process is: map ASFs once; run a reference station; and broadcast corrections. That’s it! With good signal-to-noise ratio and transmitter geometry, 10-meter or better accuracy can be obtained.
Measuring ASFs
The GLA have had the ability to measure ASFs for several years, using a combination of commercial hardware and proprietary software (Figure 2).
Figure 2. GLA-produced software for ASF survey, processing, and validation.
The software, written in Matlab, shows a real-time plot of the survey as it progresses. The ASF values are color-coded according to magnitude. The software can also process the ASF data once it has been measured, to get the best performance out of it. The real-time capabilities of the software allow the determination of the quality of the data while aboard the ship, rather than having to wait until back in the laboratory. Statistical analysis of the data can also show where the ship should go to gather more data in a particular area.
Once the survey is complete, the software can be used to generate interpolated grids of ASF data — the most convenient and accurate form of ASF data storage.
It is important with any scientific or engineering measurement to establish the error on that measurement. The same can be said of ASFs, and so the software can calculate the error bounds on ASF measurements. This “ASF error” data can again be published in grid form alongside the ASF database. This allows it to be used as one component of an Integrity Equation, implemented within the mariner’s receiver, to calculate Horizontal Protection Level (HPL).
After processing, the ASF data should be validated by performing a harbor approach or other maneuver that requires a particular positioning accuracy. For this, the software can be switched to “Validation” mode. Once the validation is successful, the data can be output in a publication format (RTCM SC-127 format for example).
The plot in Figure 2 shows part of an ASF database for Harwich and Felixstowe, major ports on the east coast of the UK. Using this data and DLoran in the Harwich and Felixstowe approach provides 10-meter (95 percent) positioning accuracy.
UK eLoran Prototype
This prototype eLoran system works alongside GPS. It has been in operation 24 hours a day since May 2010. It is “prototype” because it demonstrates the concept of eLoran using signals from existing Loran-C stations in Norway, the Faroe Islands, Germany, and France plus the UK’s station at Anthorn; see Figure 3.
Figure 3. Relevant European Loran-C stations for prototype eLoran.
These stations, together with ASF measurements and DLoran, can deliver a high-precision eLoran service in ports where 10-20 meter accuracy is needed, across the area enclosed by the green contour in Figure 4.
Figure 4. Coverage of prototype eLoran over the UK and Ireland.
It is very impressive, yet the full availability and accuracy benefits of eLoran are still to come as these stations are eventually upgraded to full eLoran capability. And for the last year or so, the GLA have begun to move beyond the confines of the Harwich and Felixstowe approaches and implement initial eLoran services in other regions around the GLA service area.
The GLA aim to do this in two stages. In the first stage Initial Operational Capability (IOC) service will be installed by mid-2014, with the second stage Full Operational Capability (FOC) service covering all major ports in the UK and Ireland, plus Traffic Separation Schemes, installed by 2019 or so in time for e-Navigation.
Initial Operational Capability
IOC involves upgrading the installation at Harwich and Felixstowe and new installations in the approaches to another six of the busiest ports in the UK: Aberdeen, Grangemouth, Middlesbrough, Immingham, Tilbury, and Dover. For each of these areas an ASF survey and a DLoran reference station will be required.
The corrections for these reference stations will be broadcast using the Anthorn Loran Data Channel. There is also the need for a Monitoring and Control System for the network of DLoran Reference Stations, and it is envisaged that this will be based in Harwich. Figure 5 illustrates the architecture of the Initial Operational Capability system. The diagram shows the major components: eLoran transmitter, DLoran reference station network, monitor, and control system. Also shown are the interfaces between the components, which provide not only operational data but also include the ability to monitor the integrity of the system. Also note that the Loran Data Channel is capable of supporting third-party messaging applications using a client “logon” facility. This is already being done at Anthorn.
Figure 5. The architecture of the UK GLA’s eLoran Initial Operational Capability.
The European tender process for seven operational reference stations and the control system is almost complete.
The aim of IOC is to provide areas for demonstrations and trials, so that the mariner can gain experience of the system and its capabilities and provide feedback to the GLA on its performance.
eLoran at the Port of Dover
In the absence of the final operational reference stations, the GLA decided to perform an early implementation using prototype equipment that was already available at the GLA. The choice for this implementation was obvious: the iconic Port of Dover, a major port on the southeast coast of the UK and the Dover Strait, one of the busiest seaways in the world. Some 500-plus vessels travel through the Strait each day on their way to or from the North Sea region; see Opening Figure.
The GLA have, with the agreement of Port of Dover Operations, installed a prototype DLoran Reference Station within the port’s Terminal Control building. The roof of the building is an ideal location for the reference station receiver antenna as the location demonstrates low noise in the eLoran band and has easy access to mains power, cable runs, antenna mounts, and Internet access.
The ASF survey took place in March 2012, and covers the area outlined by the yellow polygon in Figure 6.
Figure 6. Area of March 2012 ASF survey.
Accuracy Performance Validation
Once the ASFs had been measured and the prototype reference station installed, the performance needed to be tested. This was accomplished through a validation run of the vessel through the area.
Figure 7 shows a screenshot of the GLA ASF measurement software running in validation mode. The colored track shows the path of the vessel, with the color indicating the positioning error compared to differential GPS. The vessel travels through an area of extrapolated and interpolated ASF data, so the positioning error at the northern end of the track is higher than the lower end of the track.
Figure 7. Screenshot of GLA ASF measurement software running in validation mode.
Figure 8 shows a comparison of eLoran positioning against DGPS positioning along the route as a scatter plot. The associated Cumulative Distribution Function (CDF) is shown on the right of the diagram. From this it can be seen that the positioning accuracy obtained along this particular route was 12.5 meters (95 percent).
Figure 8. eLoran positioning accuracy scatter plot and cumulative distribution function of positioning error. Accuracy: 12.5 m (95%)
Dover to Calais Ferry Installation. Further validation and demonstrations will take place aboard a cross-Channel ferry. P&O Ferries in the UK has installed a receiver aboard their vessel, The Spirit of Britain. This relatively new vessel is one of the largest passenger ships to operate along the iconic Dover to Calais route. Data will be collected and feedback obtained on the eLoran service’s performance over the coming months.
Other Areas
The GLA continue their work towards IOC-level eLoran. Dover was the first port of call for the GLA eLoran Initial Operational Capability — the ASFs have been mapped and a prototype DLoran reference station has been installed. The final operational DLoran reference stations should be available this time next year.
The next area the GLA have concentrated upon is the Thames Estuary up to Tilbury. Although the GLA have not yet installed a permanent DLoran reference station, the ASF survey was performed in November 2012 using a temporary reference station installed at Medway. Along the route shown in Figure 9, a validation trial demonstrated 8.3 meters (95 percent) accuracy (Figure 10). The GLA have also recently surveyed the River Humber, including its approaches, up to the port of Hull. The data is currently in the process of being validated.
Figure 9. ASF map validation route from the port of Medway heading out of the River Thames estuary.Figure 10. eLoran positioning accuracy scatter plot and cumulative distribution function of positioning error. Accuracy: 8.3 m (95%).
Status and Next Steps
The next steps are to continue the implementation of IOC eLoran at the remaining port approaches for this phase. It is the aim that all ASF surveys will have been performed by the middle of 2014 in readiness for the installation of the operational DLoran reference stations at each candidate port. Licence agreements are being established with the various port authorities involved in order to allow this.
All ports that have been approached are positive and are keen to assist in the GLA eLoran implementations. eLoran noise surveys have been performed at all ports and locations for all DLoran reference stations have been found.
The Port of Dover has prototype eLoran up and running and has demonstrated 12.5-meter (95 percent) accuracy during the limited validation performed so far; however, further validation continues aboard the Spirit of Britain ferry.
The Thames Estuary ASF Survey has been performed, and 8-meter (95 percent) accuracy has been demonstrated in the area. The River Humber and its approaches have also been surveyed with validation in progress.
IOC-level DLoran reference stations should be available mid-2014, ready for installation.
The methods and processes employed during this work will be proposed for inclusion within the next version of the eLoran receiver Minimum Performance Specification as determined by Radio Technical Commission for Maritime Services (RTCM) Special Committee 27. These include techniques and algorithms used for ASF measurement processing, the preferred ASF file format, guidelines on the usage of ASF data, and integrity computation.
Acknowledgments
The GLA acknowledge the assistance of the crew of THV Alert, the Dover Harbour Board, Peel Ports (Medway), Associated British Ports (Humber), Aberdeen Harbour Authority, Forth Ports, PD Ports (Middlesbrough).
This article is based on a presentation made at the Institute of Navigation International Technical Meeting, January 2013, in San Diego, California.
Paul Williams is a principal development engineer with the Research and Radionavigation Directorate of the GLA, and technical lead of the GLA’s eLoran Work Programme, responsible for the ongoing roll-out of the GLA’s eLoran Initial Operational Capability (IOC). He holds a Ph.D. in electronic engineering from the University of Wales.
Chris Hargreaves is is a research and development engineer with the Research and Radionavigation Directorate Directorate of the GLA. His work focuses on eLoran in measurement trials, software development, and data analysis. He holds a masters’ degrees in mathematics and physics from the University of Durham and in navigation technology from the University of Nottingham.
Aeroflex Incorporated, a wholly owned subsidiary of Aeroflex Holding Corp., has announced its capability to simulate WAAS (Wide Area Augmentation System) LPV (Localizer Performance with Vertical Guidance) approaches by adding this new feature to their GPSG-1000 Portable GPS Simulator.
Aeroflex has developed the capability of simulating WAAS LPV approaches to expedite and validate the installation of WAAS-enabled navigation systems in aircraft. The GPSG-1000 offers the following features to installers of these systems:
Ability to perform structured, repeatable dynamic motion tests (actual flight) of a WAAS/LPV installation,
Ability to check and validate the sensitivity and dynamic range of an airborne GPS receiver, either statically or while in motion,
Reduce aircraft down time and flight demonstration time required by FAA,
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New orders for the GPSG-1000 are ready for immediate delivery. For existing GPSG-1000 customers, a no-charge software upgrade will be available by mid-April 2013.
The FAA created the WAAS program in 1992 to provide the necessary integrity to utilize GPS signals for precision approach. The WAAS consists of a network of precisely surveyed wide area reference stations (WRS). These reference stations monitor GPS satellites to determine errors in the GPS satellite signal. Each reference station relays the information about the GPS satellites to the WAAS wide area master stations (WMS). The master station then develops corrections to the GPS position information and provides timely notification of unreliable GPS data. These corrections are sent to ground uplink stations (GUS) where they are transmitted in the form of a WAAS correction message to a Geostationary Earth Orbit (GEO) satellite. The WAAS signal is then broadcast to users on the same frequency as GPS. This WAAS corrected signal provides three-dimensional guidance to aircraft.
Video VBOX Waterproof by Racelogic combines a powerful GPS data logger with a high-quality multi-camera video recorder and real-time graphics engine, allowing users to carry out detailed driver training and vehicle analysis whatever the weather. Housed in a water-resistant anodized aluminium casing (IP66), Video VBOX Waterproof incorporates a flange and mounting holes to permit users to bolt the system anywhere on their vehicle.
The unit takes video from up to two bullet cameras and combines it with a customizable graphical overlay, recorded on to SD card or USB stick in DVD quality. It is designed for a variety of applications from automotive testing to motorsport, driver training, and industrial applications.
The TraceME micro by KCS BV is a small GPS / GPRS tracker that fits inside a key chain. It is targeted for personal use and any application that need a minimum size while maintaining the exact same options and server connection full-size units have. KCS TraceME GPS / GPRS modules enable remote tracking of objects such as cars, trucks, containers, and motorcycles.
Equipped with a 65-channel Skytraq Venus634LPx GPS receiver, the KCS TraceME Module provides reliable and accurate navigational data. All communication is handled rapidly and effectively by a GPRS/GSM modem (quad-band) through GPRS or SMS. In areas without network coverage, position data and events are stored in memory (up to 55,000 positions). As soon as communication is restored, all information can be transmitted. The user-configuration menu controls actions such as sending position information, depending on all possible events. All of the necessary server-side scripts to process and store data from the TraceME units are available free of charge.
Evaluation Kit NV08C-EVK-CSM by NVS Technologies is a set of instruments for a developer of systems based on NVS Technologies’ NV08C-CSM module. Use of EVK-CSM is a convenient way to learn functionality of NV08C-CSM and begin system design.
The EVK-CSM may be used in navigation systems to obtain the current position (latitude, longitude and elevation), velocity vector, and time GNSS signals including GPS, GLONASS, Galileo, Compass, and SBAS in any location on Earth and at any time. The EVK-CSM is a flexible tool that allows users to evaluate various modes of operation of the NV08C-CSM and to override a default configuration and connection diagram with jumpers.
Connectors and jumpers on EVK-CSM PCB provide simple monitoring of intermediate signals and parameters (digital IOs state, power supply voltages, and currents on individual supply inputs).
