GTX Corp, which specializes in putting GPS technology in consumer products, and Atlantic Footcare have signed a manufacturing and distribution agreement to develop and launch GPS embedded insoles. Under the agreement, Atlantic Footcare will be making an investment of $200,000 to advance the development of the new GPS SmartSoles.
Atlantic Footcare, headquartered in Rhode Island, has been a designer and manufacturer of insoles for more than twenty years and supplies many of the major athletic and shoe companies, national retail chains, and the U.S military with high-quality and comfort insoles. Atlantic Footcare has experience in embedding electronics inside insoles through other partnerships and alliances and has completed the first prototypes of the GPS SmartSoles, which are undergoing testing.
“This relationship and investment with GTX is a great opportunity to couple technology with an insole, enabling us to produce a truly innovative and cost effective solution to meet today’s growing personal tracking needs. We are very excited at the opportunity to be at the forefront of wearable GPS tracking technology,” said Charlie Sipes, Atlantic Footcare president.
GTX Corp had been researching ways to further miniaturize its GPS module to penetrate new markets and expand current ones. “Compared to our existing module, this next gen is approximately 30 percent smaller, thinner, and lighter; 20 percent less expensive; and has 200 percent more battery life. It is equipped with a motion sensor and advanced A-GPS technology for pinpoint accuracy and rapid time to first fix,” said GTX Corp CEO Patrick Bertagna. “The opportunity to partner with Atlantic Footcare opened up and with this latest next generation device, embedding the module inside an insole was a natural next step.”
INTRUSION SENSORS strive to have a high detection rate and low false alarm rate.
By Eric Olson and Steven Pisciotta
Ongoing threats from terrorist activities at critical facilities require early detection before the threats can reach their target and complete their mission. This has produced the need for advanced security systems to effectively detect terrorist activity, while reducing alarms caused by normal friendly activity. Automatic Threat Assessment, also referred to as Identify Friend or Foe (IFF), is the ability to automatically acknowledge alarms created by friendly assets. It can be achieved with a security system that uses GPS and geospatial data to go beyond the typical intrusion-sensor-only configuration.
The addition of a tracking system associated with friendly vehicles and personnel can provide the missing information necessary to tighten security and reduce the need to take action on alarms caused by friendly targets, and reduce the material and personnel cost of threat assessment. Tracking systems and intrusion sensors can worktogether to automatically classify an actual intruder with high confidence and without operator intervention.
The Verification Problem
Typical intrusion sensors include intelligent fences, ground proximity sensors, radar, LIDAR, and video analytics. The role of the intrusion sensor is to identify a breach and notify security personnel so they may perform verification. Table 1 shows the formal alarm types received from intrusion sensors, which strive for a high detection rate and a low false-alarm rate. For this reason, the nuisance alarm can be problematic as it reflects a real event for the intrusion sensor, but often a non-event for the security operator.
These typical sensors only provide a “suspected intruder” list. The follow-on task is to decide whether or not to reclassify a suspected intruder as an actual intruder. This process is typically a manual task and can be difficult, confusing, and time-consuming.
For instance, a landscape crew will trigger alarms. Even for very accurate systems that can uniquely track the object over a long period, it is highly likely that over the period of time the landscapers are in the area, the track will be lost, causing the system to re-alarm on the same person or vehicle, as it represents a potential intrusion.
If the landscaping crew needs to open a gate, and that gate is integrated into the facility’s access control system via a dry contact or beam breaker device, it may continuously alarm while left open, or at a minimum, in the case of the beam, each time one of the workers or the vehicle passes through the entrance. In these situations, security will either need to validate each alarm by verifying it on a camera or having an officer follow the landscaping crew throughout their route.
The existence of a friendly alarm event that needs continual validation can lead to compacency of security personnel, either not verifying it, or not verifying it in a timely manner.
Table 1. Alarm types.
Combined Detection, Location
A GPS tracking system combined with the intrusion sensors can help identify friends. Tracking systems consist of two main types of locating devices: GPS-enabled devices and wireless transponders.
Modern, low-cost GPS receivers can achieve an accuracy rating of less than 3 meters, provide an update once per second, and do not require visibility to the open sky. Wireless communication transmits the GPS data to the C2 system. A typical data set includes time, date, latitude, longitude, altitude, heading, speed, and quality of GPS signal.
The combination of intrusion sensors and tracking systems can produce automatic threat assessment. Routine situations requiring significant security involvement, such as the landscaping scenario, can be automatically managed by the system. The command and control system has the ability to know friendly targets and their location.
Further, the system can perform a check before actually alarming. In the case of a perimeter alarm, it now has the intelligence to understand, within a level of confidence, that the object detected by the intrusion sensors is the same friendly item being tracking by the tracking system. If the system determines the targets to be the same object, the alarm can be suppressed, eliminating the need for security to verify the event.
THE COMBINATION of intrusion sensors and a tracking system allows for Automatic Threat Detection.
Common Operating Picture
The integration of these types of systems is not complex in terms of how to coordinate data. Interface documents exist for these types of integration and are done on a regular basis. Typical position and target information is communicated over XML in a standard format. However, to gain these benefits, the tracking systems and intrusion sensors must all work within a common geospatial operating picture.
Advantages of geospatial or geo-referenced systems systems include the ability to easily display and control data in a map-based format, allowing tracking systems and intrusion sensors to synergistically perform automatic verification. This combined knowledge of the target’s track also allows the fusing of the GPS data and the intrusion sensor data into a single object and path, aiding security by reducing target and track clutter on his command and control or PSIM (perimeter security information system).
Take for example a guard enabled with a tracking device, performing a tour around a fence protected by video analytics enabled cameras. On a typical PSIM, a normal guard tour would result in two icons on the display, one friendly from the tracking system and one unknown from the video analytics. This scenario would also result in two similar object tracks. Security would need to review the situation and understand that this symbology represents a single target and a single track.
Integrating the tracking system with the video analytics system allows for a fusing of this data, and the resulting command-and-control symbology is a single target and a single track.
Other considerations when combining a tracking system with intrusion sensors include update rate, time and location accuracies, and overlapping coverage.
Ideally, all sensors would be synchronized when it comes to timing aspects, but this is typically not the case. Different timing between data updates and time inaccuracies can result in the inability for the systems to confidently conclude that two tracks were created by the same target. Transport delay, the transmission of the GPS data through the satellite, can also be an issue. For tracking devices, it’s vital for the data to be received by the C2 system with a repeatable transport delay. Variability in the transport delay also decreases the ability to automatically verify the threat.
Geographic accuracy of both the GPS tracker and the intrusion sensor is another important factor in data fusion. Typical GPS trackers have an accuracy rating of 3–10 meters. Actual accuracy varies based upon the visible GPS satellites, tall buildings, body worn, and RF interference. Intrusion sensors also possess an inherent accuracy. Radar surveillance may have a resolution of 1 x 1 meter at close range, but it expands at far range to 1 x 20 meters.
Intelligent fence sensors and video analytic systems can have resolutions that vary from 1 to 25 meters, based on the type of sensor and the terrain. These geographic inaccuracies can be handled to some degree by considering other factors, including heading, speed, and previous track, but it’s important to understand where these inaccuracies can occur.
Overlapping coverage of surveillance sensors also affects data fusion. In the case of track fusion, this ability is only available is areas where both a geospatial intrusion sensor exists and a tracking system is operational. If there are gaps in overlapping coverage, or areas that do not include geospatial- based intrusion sensors, then fusion is not possible in those regions.
Eric Olson is vice president of Marketing at PureTech Systems.
Steven Pisciotta is president of Remote Tracking Systems.
INTRUSION SENSORS strive to have a high detection rate and low false alarm rate.
By Eric Olson and Steven Pisciotta
Ongoing threats from terrorist activities at critical facilities require early detection before the threats can reach their target and complete their mission. This has produced the need for advanced security systems to effectively detect terrorist activity, while reducing alarms caused by normal friendly activity. Automatic Threat Assessment, also referred to as Identify Friend or Foe (IFF), is the ability to automatically acknowledge alarms created by friendly assets. It can be achieved with a security system that uses GPS and geospatial data to go beyond the typical intrusion-sensor-only configuration.
The addition of a tracking system associated with friendly vehicles and personnel can provide the missing information necessary to tighten security and reduce the need to take action on alarms caused by friendly targets, and reduce the material and personnel cost of threat assessment. Tracking systems and intrusion sensors can worktogether to automatically classify an actual intruder with high confidence and without operator intervention.
The Verification Problem
Typical intrusion sensors include intelligent fences, ground proximity sensors, radar, LIDAR, and video analytics. The role of the intrusion sensor is to identify a breach and notify security personnel so they may perform verification. Table 1 shows the formal alarm types received from intrusion sensors, which strive for a high detection rate and a low false-alarm rate. For this reason, the nuisance alarm can be problematic as it reflects a real event for the intrusion sensor, but often a non-event for the security operator.
These typical sensors only provide a “suspected intruder” list. The follow-on task is to decide whether or not to reclassify a suspected intruder as an actual intruder. This process is typically a manual task and can be difficult, confusing, and time-consuming.
For instance, a landscape crew will trigger alarms. Even for very accurate systems that can uniquely track the object over a long period, it is highly likely that over the period of time the landscapers are in the area, the track will be lost, causing the system to re-alarm on the same person or vehicle, as it represents a potential intrusion.
If the landscaping crew needs to open a gate, and that gate is integrated into the facility’s access control system via a dry contact or beam breaker device, it may continuously alarm while left open, or at a minimum, in the case of the beam, each time one of the workers or the vehicle passes through the entrance. In these situations, security will either need to validate each alarm by verifying it on a camera or having an officer follow the landscaping crew throughout their route.
The existence of a friendly alarm event that needs continual validation can lead to compacency of security personnel, either not verifying it, or not verifying it in a timely manner.
Table 1. Alarm types.
Combined Detection, Location
A GPS tracking system combined with the intrusion sensors can help identify friends. Tracking systems consist of two main types of locating devices: GPS-enabled devices and wireless transponders.
Modern, low-cost GPS receivers can achieve an accuracy rating of less than 3 meters, provide an update once per second, and do not require visibility to the open sky. Wireless communication transmits the GPS data to the C2 system. A typical data set includes time, date, latitude, longitude, altitude, heading, speed, and quality of GPS signal.
The combination of intrusion sensors and tracking systems can produce automatic threat assessment. Routine situations requiring significant security involvement, such as the landscaping scenario, can be automatically managed by the system. The command and control system has the ability to know friendly targets and their location.
Further, the system can perform a check before actually alarming. In the case of a perimeter alarm, it now has the intelligence to understand, within a level of confidence, that the object detected by the intrusion sensors is the same friendly item being tracking by the tracking system. If the system determines the targets to be the same object, the alarm can be suppressed, eliminating the need for security to verify the event.
THE COMBINATION of intrusion sensors and a tracking system allows for Automatic Threat Detection.
Common Operating Picture
The integration of these types of systems is not complex in terms of how to coordinate data. Interface documents exist for these types of integration and are done on a regular basis. Typical position and target information is communicated over XML in a standard format. However, to gain these benefits, the tracking systems and intrusion sensors must all work within a common geospatial operating picture.
Advantages of geospatial or geo-referenced systems systems include the ability to easily display and control data in a map-based format, allowing tracking systems and intrusion sensors to synergistically perform automatic verification. This combined knowledge of the target’s track also allows the fusing of the GPS data and the intrusion sensor data into a single object and path, aiding security by reducing target and track clutter on his command and control or PSIM (perimeter security information system).
Take for example a guard enabled with a tracking device, performing a tour around a fence protected by video analytics enabled cameras. On a typical PSIM, a normal guard tour would result in two icons on the display, one friendly from the tracking system and one unknown from the video analytics. This scenario would also result in two similar object tracks. Security would need to review the situation and understand that this symbology represents a single target and a single track.
Integrating the tracking system with the video analytics system allows for a fusing of this data, and the resulting command-and-control symbology is a single target and a single track.
Other considerations when combining a tracking system with intrusion sensors include update rate, time and location accuracies, and overlapping coverage.
Ideally, all sensors would be synchronized when it comes to timing aspects, but this is typically not the case. Different timing between data updates and time inaccuracies can result in the inability for the systems to confidently conclude that two tracks were created by the same target. Transport delay, the transmission of the GPS data through the satellite, can also be an issue. For tracking devices, it’s vital for the data to be received by the C2 system with a repeatable transport delay. Variability in the transport delay also decreases the ability to automatically verify the threat.
Geographic accuracy of both the GPS tracker and the intrusion sensor is another important factor in data fusion. Typical GPS trackers have an accuracy rating of 3–10 meters. Actual accuracy varies based upon the visible GPS satellites, tall buildings, body worn, and RF interference. Intrusion sensors also possess an inherent accuracy. Radar surveillance may have a resolution of 1 x 1 meter at close range, but it expands at far range to 1 x 20 meters.
Intelligent fence sensors and video analytic systems can have resolutions that vary from 1 to 25 meters, based on the type of sensor and the terrain. These geographic inaccuracies can be handled to some degree by considering other factors, including heading, speed, and previous track, but it’s important to understand where these inaccuracies can occur.
Overlapping coverage of surveillance sensors also affects data fusion. In the case of track fusion, this ability is only available is areas where both a geospatial intrusion sensor exists and a tracking system is operational. If there are gaps in overlapping coverage, or areas that do not include geospatial- based intrusion sensors, then fusion is not possible in those regions.
Eric Olson is vice president of Marketing at PureTech Systems.
Steven Pisciotta is president of Remote Tracking Systems.
The chief designer of the BeiDou Navigation Satellite System said China will advocate the use of the system, which will be compatible with new devices, “so that Beidou can function properly and independently even if something goes wrong with the GPS.”
Sun Jiadong, chief designer of BDS and an academician of the Chinese Academy of Sciences, made his comments in an interview with The Beijing News, as reported by the Chinese government’s website.
He added that this compatibility is the only way to ensure the protection of national information. “Safety issues abound in economic areas,” said Sun. “Ordinary people may have few concerns about the security of information but it is of vital significance.”
The development of Beidou also largely depends on the government’s involvement. “Even though the enterprises spare no effort in developing the system, the products they make would not be available for mass production, which will in turn be reflected by the prices. The government has to promote the research and development of the system,” Sun said. Sun cited the governments of Beijing, Shanghai, and Guangzhou as examples of local governments that were effectively helping to develop the BDS.
The use of Beidou could go beyond basic navigation functions and extend to the civilian market. It would take longer for the BDS to be available for civilians, said Sun. The use of Beidou on mobile phones relies on the development of a small and power-efficient chip. Otherwise the phone cannot be used.
When asked about when and how the cost of developing the BDS will be recovered, Sun reiterated that Beidou was developed to ensure the security of national information, and not to make profits.
The Beidou global navigation system will be available by 2020 with the launching of more than 30 satellites.
An ITT Exelis product that detects and locates GPS interference sources in 3-D by using longitude, latitude and altitude has successfully completed a significant integration milestone.
Signal Sentry 1000, formerly known as GPS Interference, Detection and Geolocation, may now be deployed to collect actionable intelligence for law enforcement, such as tracking high-value targets and protecting critical infrastructure.
Signal Sentry 1000 is a proprietary product that leverages GNSS signal domain knowledge; it is based upon patented technology developed by Exelis through many years of designing and fielding electronic intelligence systems, ITT Exelis said.
“Exelis developed Signal Sentry 1000 to help protect critical infrastructure and to deliver intelligence to law enforcement operations that depend upon GPS availability,” said Kevin Farrell, positioning, navigation and timing general manager for Exelis Geospatial Systems. “Jamming devices can transmit signals capable of disrupting the synchronization of critical infrastructure, such as utility power grids, and timing information of financial transactions. This is why we are continually making improvements in our technology, and the latest milestone achievement is a testament to our goal to deliver actionable interference intelligence to agencies that rely upon GPS operational availability.”
Signal Sentry 1000 technology is a network of threat-detection sensors, which are part of a centralized server executing Exelis‐developed proprietary location algorithms. These sensors can be strategically located around areas of critical infrastructure, such as shipping ports, utilities and government facilities to automatically sense and locate any intentional or unintentional GPS jamming source. Should a threat be detected, users would receive accurate location information and actionable intelligence in order to determine an interference-mitigation plan.
“Signal Sentry 1000 builds upon Exelis expertise in the field of GPS and positioning, navigation and timing. Exelis payloads and payload components have been on board every GPS satellite for nearly 40 years,” said Farrell. “Today, Exelis is involved in GPS modernization initiatives, building tomorrow’s GPS III satellite constellation by developing and integrating the navigation payloads. Exelis is also providing navigation processing components, precision monitor station receivers, and key components of the system security design for the GPS Operational Control System, also known as OCX.”
ITT Exelis is offering the Signal Sentry 1000, a proprietary product that detects, geolocates, and characterizes sources of intentional and unintentional interference to the U.S. GPS signals, and provides actionable intelligence to the user.
The system leverages GNSS signal domain knowledge, and is based upon patented technology developed through the company’s history of designing and fielding electronic intelligence systems, ITT Exelis said.
Leveraging Exelis GNSS signal domain knowledge, the system is implemented using commercially available GPS receiver and computer server/data technology. Actionable intelligence is available in the form of pin mapping of interference sources in addition to longitude/latitude/altitude data, all available through a web-enabled graphical user interface.
Signal Sentry 1000 can assist efforts to ensure GPS spectrum integrity and aid in law enforcement operations that require GPS availability. Benefits for users include:
Instantaneous identification and geolocation of jamming sources, improving situational awareness.
Skyhook Wireless, a provider of location positioning, announced a partnership to integrate Skyhook’s hybrid location platform into Comodo’s Anti-Theft app for Android devices.
Comodo’s Anti-Theft for Android is a new service that enables customers to remotely locate, lock and recover a lost or stolen Android smartphone or tablet. The app can remotely capture and upload photos of whoever is operating the missing device to aid authorities in their recovery efforts and also in identifying the thief. The product is designed to address the security, monitoring, and management needs of users with limited time and IT support.
“Comodo selected Skyhook’s leading hybrid location service because of its precision, speed, and power efficiency, all of which are critical to Comodo in our mission to locate, track, and recover lost or stolen devices,” said Melih Abdulhayoglu of Comodo.
Comodo Anti-Theft for Android is free and available at the Android Play Store. Skyhook provides an SDK for developers across most platforms.
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.
New technology from product development firm Cambridge Consultants can accurately detect someone’s location indoors when GPS drops out. A number of sensors and a custom algorithm determine the location, with an accuracy of within approximately 1 percent of the distance traveled.
The technology uses low-power, low-cost sensors and the device concept is small enough to clip on a belt. It also doesn’t need any existing internal infrastructure.
“We are excited about the many possibilities this cutting-edge technology opens up and the impact it can have in many different situations,” said Geoff Smithson, technology director, sensing systems, at Cambridge Consultants. “It could be used to help locate firefighters in smoke-filled buildings, for example, or to pinpoint the closest doctor in a hospital during an emergency — or to track offenders during home curfews. We are just starting to see the potential of this approach and the diverse demand for this type of low-energy, highly accurate system.”
Indoor tracking systems, which process data from one or more sources of location information to estimate where a person or object is located, are not new. But they often rely on RF signals from Wi-Fi access points or custom infrastructure, poor-quality GPS signals or expensive, high-quality sensors. The availability of low-cost smartphone components — including accelerometers, gyroscopes, magnetometers and pressure sensors — has enabled a new generation of location devices and applications, when combined with a tailored Bayesian algorithm to fuse the information.
The new technology platform can be embedded in an existing design or operate as a stand-alone unit, with options to compute the location locally or transmit the information to a remote system that can process the data before visualizing it on a smartphone app.
“Our biggest challenges were developing an algorithm which optimally combines the data from GPS and the other sensors, and overcoming the issues of using such low-cost sensors in a system without any absolute location reference,” said Smithson.
Cambridge Consultants specializes in developing low-cost, low-power connected devices for clients with a team of experts with sensing, wireless and software engineering expertise. The latest technology builds on the company’s tracking and location systems experience in a variety of market sectors ranging from defense and security to consumer, industrial, and oil and gas.
Next month Spirent is hosting a meeting with hands-on training sessions on GNSS simulation equipment led by Spirent engineers. The 2013 Spirent Federal 2013 GNSS Technical Interchange Meeting will be held March 19-21 at the DoubleTree Hotel Anaheim-Orange County, in Orange, California.
March 19 and 20 are for general participation. The third day, March 21, features FOUO (For Official Use Only) sessions for U.S. citizens only.
The General Lighthouse Authorities of the UK and Ireland (GLA) have announced that ships in the Port of Dover, its approaches and part of the Dover Strait can now use eLoran radio navigation technology as a backup to satnav systems like GPS and Galileo. What is considered the world’s busiest shipping route is the first to deploy eLoran to counter jammers and space weather, the GLA said in a statement.
The ground-based eLoran system provides alternative position and timing signals for improved navigational safety. The Dover area, the world’s busiest shipping lane, is the first in the world to achieve this initial operational capability (IOC) for shipping companies operating both passenger and cargo services.
Today’s announcement represents the first of up to seven eLoran installations to be implemented along the East Coast of the United Kingdom. The Thames Estuary and approaches up to Tilbury, the Humber Estuary and approaches, and the ports of Middlesbrough, Grangemouth and Aberdeen will all benefit from new installations, and the prototype service at Harwich and Felixstowe will be upgraded, the GLA said.
Although primarily intended as a maritime aid to navigation, eLoran could become a cost-effective backup for a wide range of applications that are becoming increasingly reliant on the position and timing information provided by satellite systems.
“Our primary concern at the GLA is for the safety of mariners,” said Captain Ian McNaught, Chief Executive of Trinity House. “But signals from eLoran transmitters could also provide essential backup to telecommunications, smart grid and high frequency trading systems vulnerable to jamming by natural or deliberate means. We encourage ship owners and mariners to assess eLoran in this region and provide feedback to the GLA on its performance.”
P&O Ferries has installed an eLoran receiver on its new vessel Spirit of Britain. She will be based at Dover and is one of the largest passenger ships the busy Dover/Calais route has ever seen.
“Accurate real-time positional information is essential for the safe navigation of ships with modern electronic charts,” Captain Simon Richardson, head of Safety Management at P&O Ferries, said. “Satellite navigation systems are vulnerable to degradation of signal strength and our ships have also experienced occasional loss of signal. We welcome the development of a robust alternative to provide redundancy in real-time positional information and we see eLoran as the most effective solution to countering the problem.”
Commenting on the announcement Stephen Hammond, Minister for Shipping, said, “I congratulate the General Lighthouse Authorities on this initiative that seeks to improve navigational safety in what is the busiest shipping channel in the world, through the development and deployment of technology. I look forward to receiving reports of its effectiveness.”
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