GPS World

Category: GNSS

  • It’s Leap Second Day! Time to Get in Sync

    Leap-Second-O

    “Time waits for no one,” Mick Jagger lamented in song when he turned 30. But tonight, on the evening of June 30, our clocks will stand still for a moment, waiting for the passage of a “leap second.”

    The International Earth Rotation and Reference Frames Service (the world’s time monitor) has decreed that the last day of June will contain an extra second. Rather than the usual 86,400 seconds in a day, June 30 will have precisely 86,401 seconds.

    National time-keeping centres around the globe, such as the National Research Council in Ottawa, will insert this extra second or leap second into their master clocks so that they remain synchronized with an international time standard. All other clocks that get their time from a master clock will be updated similarly. This includes all of the so-called time servers on the Internet, which keep our computer clocks in sync.

    This global time standard is called UTC or Coordinated Universal Time. The standard was established in the 1960s once it was demonstrated that the newly developed atomic clocks could keep time with unprecedented precision and that clocks, even if they were on different continents, could be synchronized with each other to a fraction of a microsecond.

    UTC is the time system kept in most countries straddling or bordering the prime meridian at zero degrees of longitude. The civil time systems in regions to the east and west of the prime meridian are typically offset by an integral number of hours from UTC. Atlantic Time, for example, is currently three hours behind UTC, so the leap second will occur here just before 9 p.m.

    UTC (and the various zone or regional time scales related to it such as Atlantic Time) has replaced the previously used time scale based on the Earth’s rotation with respect to the sun for most civil time-keeping purposes.

    Although the Earth appears to rotate uniformly with night following day since time immemorial, the Earth actually does not spin at a constant rate. It fluctuates slightly due to a variety of causes including variations in winds and ocean currents, the motions of the Earth’s fluid core, and the friction of tidal currents flowing along the bottom of the oceans.

    Tidal friction and the other effects has resulted in a long-term or secular decrease in the Earth’s rate of rotation resulting in an increase in the length of the solar day of a little over 1 millisecond per day per century. Currently, the length of the day is roughly 2 milliseconds longer than it was in the early 1800s when it was exactly 86,400 seconds. This means that over a period of 1,000 days, a clock keeping time based on the rotation of the Earth, a time scale known as UT1, would lose about 2 seconds compared to UTC, which is based on the atomic second and referenced to the period of the Earth’s rotation around 1820.

    To keep UTC to within 0.9 second of UT1, leap seconds are periodically added to UTC. While tidal friction is the primary reason for adding these leap seconds, the other factors responsible for the variation in the Earth’s spin contribute as well. In fact, negative leap seconds are theoretically possible, although all leap seconds to date have been positive.

    The last leap second occurred on June 30, 2012. There have been 25 leap seconds added to UTC since the current system began in 1972. Leap seconds are applied either on December 31st or June 30. Two thirds of them have occurred on New Years Eves with the rest taking place at the end of June like the one coming up.

    The world runs on UTC. Everything from financial transactions to air traffic control depends on UTC and so these systems will have to properly accommodate the leap second when it happens. This includes satellite navigation systems. The Global Positioning System itself is unaffected by the introduction of a leap second because it has its own time system, GPS (System) Time, which is not adjusted for leap seconds. GPS Time was set equal to UTC back in 1980 and is currently 16 seconds ahead of it. On July 1st, this offset will increase to 17 seconds. GPS does provide UTC to its users by transmitting the necessary adjustment data in the satellite signals, permitting a receiver to compute UTC from GPS Time.

    The upcoming leap second might be the last. The International Telecommunication Union is considering a proposal that leap seconds be abolished. The justification for the proposal is that leap seconds are cumbersome and their incorrect use could lead to problems with time-dependent infrastructure including safety-of-life navigation systems.

    At an ITU meeting in Geneva in January 2012, national delegates debated a motion to eliminate the use of leap seconds in the UTC time scale. However, there was no agreement with countries evenly split in favour of, against, and undecided about abolishing leap seconds. Many of the undecided delegates said they were not sufficiently informed about the proposal to make a decision. The ITU will next consider the proposal in November 2015.

  • EGNOS Dream Now a Reality

    EGNOS demonstration equipment aboard a new Airbus A350 WXB.
    EGNOS demonstration equipment aboard an Airbus ATR-42. (Photo by Tim Reynolds)

    Toulouse, France, an aerospace city and the center of the French aerospace industry, was the birthplace of EGNOS, Europe’s satellite-based augmentation system (SBAS), in 1994. So it was appropriate that the first-ever EGNOS Flight Event was organized there in May by the European GNSS Agency (GSA) and the European Commission.

    EGNOS is the acronym for European Geostationary Navigation Overlay Service. It is also songe — the French word for “dream’”— spelled backwards and, according to Jean-Luc Moudenc, mayor of Toulouse, that is how the name originated.

    The dream is now very much a reality. Since its certification for civil aviation in 2011, EGNOS has made steady progress in implementation. Today, 111 airports in 15 countries across Europe benefit from EGNOS, and many more are preparing for implementation — 171 LPV (localizer performance with vertical guidance) and 86 BARO approaches are already certified for use.

    The EGNOS Flight Event was organized in collaboration with Airbus and brought together aviation media and other sector stakeholders for a briefing and demonstration of EGNOS, how it works, its benefits for aviation and a glimpse at its future.

    The state-of-the-art Airbus A350 WXB is the first wide-body airliner equipped with the SLS.
    The state-of-the-art Airbus A350 WXB is the first wide-body airliner equipped with the SLS. (Photo by Tim Reynolds)

    EGNOS for Airbus

    It was clear that Airbus sees integration of EGNOS, and SBAS generally, into the avionics of its product offerings, from helicopters to the giant Beluga transport plane, as very much part of the future.

    A highlight of the event was a “show and tell” with the Airbus A350 WXB — a real beauty of an airplane. Participants were given a tour of this new state-of-the-art wide-bodied airliner, including a simulation of an EGNOS-enabled LPV landing in the cockpit. Airbus test pilot Jean-Christophe Lair described the A350’s new Satellite-based Landing System (SLS) that works with SBAS such as EGNOS. This is the first time such a system has been installed on a wide-body airliner and will be supplied as a standard feature to all customers.

    EGNOS is fully integrated into a common harmonised landing system interface on the A350 — the SLS — that allows the pilot to fly precision approaches like an ILS with geometrical vertical guidance down to 200 feet. This new navigation system will allow Airbus users a wider range of solutions to optimise operations and increase accessibility without any compromise on safety.

    “All the systems look the same to the pilot — it is a seamless integration of EGNOS — so no human-factor issues,” said Jean-Christophe. Pilot feedback had been excellent with some 3,000 hours flown on LPV approaches using both EGNOS in Europe and WAAS in North America. “We have experienced no technical or operational issues with SBAS operations,” he claimed. “The SLS shows value every day that it is used.”

    SLS/LPV is operationally equivalent to CAT 1 ILS, but brings significant additional assets above the LPV minimum such as the secure coding of the final approach segment and the fact that the SBAS/ LPV vertical profile is geometric and fixed in space. The system can also be useful for creating en-route diversions and allows creation of instrumented approaches. Overall the SLS development on the A350 XWB had been a very positive experience he stated.

    Earlier Philippe Rollet, senior expert Air Traffic Management at Airbus, had said that “EGNOS was more important for helicopters than aircraft.” The enhanced EGNOS guidance enabling access to helipads in urban environments. “With EGNOS you can have a helipads everywhere and the system increases operational safety in bad weather,” he claimed. “For Airbus all new helicopter models will be EGNOS capable – it is the baseline for Airbus.”

    This enhanced access facility was demonstrated via the GSA-funded GARDEN project that is using EGNOS to enable increased safety and better access for helicopters, for example, enabling air ambulances to more easily access city centre hospitals. EGNOS implementation was demonstrated in the cockpit of an Airbus H175 multi-mission helicopter used as a test-bed for GARDEN.

    Technology at Work In Flight. EGNOS was also in action during a series of flights for the media using EGNOS for landing procedures on an ATR turboprop development craft. The plane was equipped with additional avionic displays in the main cabin, and this allowed the press to watch the technology at work without crowding out the pilots on the flight deck! The flight demonstration took off from Blagnac for a 15-minute circuit around the beautiful “pink” city of Toulouse before demonstrating an immaculate EGNOS LPV approach and landing.

    Earlier the “press pack” had also been taken on a tour of the massive assembly plant for the Airbus A380 double-decker airliner next to the airport. Well worth a visit if you are ever in the area! In fact, Toulouse is blessed with aerospace tourism attractions such as the City of Space.

    Expanding EGNOS?

    The media was welcomed to the event by GSA executive director Carlo des Dorides. He emphasised that EGNOS for aviation delivers high precision at low cost. “EGNOS is Europe’s first satellite navigation system — and already has a good success story to tell,” he said. “It helps aviation to be safer, greener and more efficient.” He highlighted EGNOS’s ability to deliver continuous integrity protection in compliance with ICAO standards allowing CAT 1 approaches with more than 99 percent availability.

    “Today 142 airports across Europe are benefitting from EGNOS, and the number is growing steadily,” he said. EGNOS’s success in aviation was also helping to spread the word for applications in other transport sectors such as maritime.

    With a near-term target of 500 runways to be EGNOS enabled in Europe, the support available for airports and operators wanting to benefit from EGNOS was emphasised by Gian Gherardo Calini, the head of market development at GSA. During 2015 the agency has allotted €6 million to co-fund projects to implement EGNOS in aviation. A similar amount had also been allocated in 2014. GSA provided technical and educational support for implementation as well as financial assistance.

    He saw the benefits being increased safety, operational enhancements, plus reduced cost and environmental impact. Widespread implementation would enable new point-to-point commercial airline opportunities.

    Key to Significant Growth. EGNOS could be the key to a significant growth in general aviation in Europe. “The need to install ILS made the business case for most general aviation airfield out of the question,” claimed Martin Robinson, senior vice president of the International Council of Aircraft Owner and Pilot Association (IAOPA). There are 4,649 aerodromes in Europe and some 50,000 general aviation aircraft operating from them. In comparison to the situation in the U.S., only a small percentage the aerodromes had been. Of course, the widespread uptake of WAAS in the U.S. is a clear result of a deliberate federal strategy.

    “There is definitely room for growth,” said Robinson. “EGNOS will help to provide greater access to aerodromes throughout Europe and to improve safety, but we need to be much quicker if we are to realise these benefits sooner.” He felt every general aviation airfield needed a clear business plan working towards EGNOS ability.

    There was some dispute about the exact cost of implementing an EGNOS approach as it varies from location to location, but in broad terms the one-off cost of implementation seems to be equivalent to the annual maintenance cost of on-the-ground ILS equipment. With these economics, wider uptake by regional airports in Europe should be a no-brainer; however, the go or no decision often came down to individuals, said Robinson. He believes European countries need to be more willing to support the European Commission in introducing the technology. Perhaps a more region-led approach is required?

    The French government line on EGNOS was given by David Comby of the French Ministry for Ecology, Sustainable Development and Energy, who said France sees EGNOS as essential part of the modernisation process for European airspace making flying safer, more efficient, greener and more cost effective. France was working hard on EGNOS implementation, and it was possible that all French runway ends (~200) would be equipped for EGNOS by 2018.

    EGNOS over Africa?

    The potential for expansion of EGNOS / SBAS across the globe is huge. Despite having to battle against a barrage of taxiing aircraft noise, Jean-Marc Piéplu Head of EGNOS Exploitation at GSA described the upgrade path for EGNOS from the current Version 2 to EGNOS V3. “Version three will feature new capabilities,” he said. “Dual-frequency and dual-constellation with both GPS and Galileo signals available.”

    In theory EGNOS V3 could provide EGNOS / SBAS coverage for aviation to more than 90 percent of the global land surface. Piéplu indicated that if the political will was there to implement, then this extension of coverage could be accomplished in 10 years. There were no outstanding technical issues. He also said that there were no current plans to use GLONASS signals with EGNOS.

    A key market could be Africa. Establishment of transport infrastructure is seen as a key enabler for sustainable development in the less-developed world, and SBAS-based infrastructure could provide a cost-effective solution to boost connectivity safely without having to invest in vulnerable ground-based equipment.

    Julien Lapie from the Agency for Air Navigation Safety in Africa and Madagascar (ASECNA) highlighted that over 40% of citizens in Africa were more than 250 miles from an ILS-equipped airport. Negotiations on use of EGNOS over Africa are ongoing, but could be completed as soon as 2016.

    As the not-so-subtle EGNOS advertising tag goes: It’s there. Use it.

  • eLoran Progresses Toward GPS Back-Up Role in U.S., Europe

    eLoran Progresses Toward GPS Back-Up Role in U.S., Europe

    eLoran-restart-W
    (fFrom left) Congressman LoBiondo, UrsaNav CEO Chuck Schue and Harris Division President Pam Drew. (hoto Credit: Andrei Grebnev, UrsaNav)

    As of June 19, eLoran is on the air in the United States. The low-frequency signal emanates from a single station, a former U.S. Coast Guard Loran Unit in Wildwood, N.J., which sports a 625-foot signal mast that has been out of action for five years. The signal is receivable at distances of up to 1,000 miles.

    The facility began generating eLoran pulses at the press of a command button by Congressman Frank LoBiondo (R, N.J). Present for the ceremonial start of a 12-month demonstration and research program under the aegis of the Department of Homeland Security were project participants Charles Schue, CEO of UrsaNav; Pam Drew, president of Harris Information Systems; and Dana Goward, president of the Resilient Navigation and Timing Foundation.

    Brief remarks delivered at the turn-on collectively made the key points that:

    • GPS services are essential to national and economic security, yet are vulnerable to disruption.
    • The eLoran navigation and communications signal has  features that are complementary to GPS, making it difficult to disrupt; further, it could be an important part of enabling UAVs to fly safely in our airspace.
    • The U.S. Federal Radionavigation Plan cites not being critically dependent upon a single system for positioning, navigation, and timing as a national policy objective. The plan specifically identifies eLoran testing as an important step toward reaching that objective.

    The two engineering companies, UrsaNav, a supplier of eLoran technology, equipment, and services, and Harris (which recently acquired Exelis), provide funding and technology for the tests supported by the U.S. Coast Guard, Department of Defense, Department of Homeland Security and other federal agencies under a Cooperative Research and Development Agreement (CRADA) announced in May.

    The team will evaluate eLoran as a potential complementary system to GPS, exploring the capabilities and use methods of eLoran in depth to identify all strengths, capacities, and potential vulnerabilities of the technology. One goal of the CRADA is to reduce the size, weight, cost, power needs and other aspects of Loran, similar to what has evolved with GPS.

    “This is a phoenix arriving. We have the opportunity to add 2015 technology to the older idea,” said Schue of UrsaNav, once Coast Guard commanding officer at the former Loran station. “A prudent mariner always has two systems to navigate.”

    Dana Goward, also a retired Coast Guardsman whose non-profit Resilient Navigation and Timing Foundation is working on the project, stated that eLoran can attain positioning accuracy of six meters or better.

    “We will explore many places eLoran can be deployed where GPS isn’t available such as deep canyons, through buildings, in foliage and under water,” added Harris Corp.’s Drew. “We’re involved with unmanned aerial drones, and eLoran could be key. There are applications for civilian and military uses.”

    In this GPS World exclusive video, Admiral Thad Allen, former commandant of the U.S. Coast Guard, discusses PNT alternatives to GPS for navigation, including eLoran and the activation this week of the signal on the eLoran tower in New Jersey.

    eLoran in Europe

    Matters have moved a little further along in Europe. In 2013, the General Lighthouse Authorities of the UK & Ireland (GLA) established prototype eLoran Initial Operating Capability (IOC) in the United Kingdom, where eLoran now delivers PNT data at the 10-meter level from a network of high-power, low frequency, terrestrial transmitters.

    “To get high accuracy from eLoran requires accurate calibration of Additional Secondary Factor (ASF) through measurement,” according to paper delivered at the Institute of Navigation’s 2015 Pacific PNT meeting. “Can eLoran Deliver Resilient PNT?” was authored by Nick Ward, Chris Hargreaves, Paul Williams, and Martin Bransby of the GLA.

    The older Loran-C system suffered from significant positioning bias errors due to a number of radio frequency signal propagation delay factors, they write. “The Primary Factor (PF) is due to the signal travelling slower in air than free-space, the Secondary Factor (SF) is due to the presence of the Earth’s surface and the electrical properties of the oceans. Additional Secondary Factor (ASF) is due to the additional electrical resistance encountered by non-seawater terrain, land, mountains, deserts, and so on. PF and SF can be modeled, but to get high accuracy from eLoran requires accurate calibration of ASF through measurement.

    “To do this,” they continue, “ASF surveying and mapping has been conducted along the port approach channels at Aberdeen; along the Firth of Forth; Middlesbrough; Hull and the Humber Estuary Traffic Separation Scheme (TSS); Harwich and Felixstowe; The ports of London, Medway and the approaches past the London Array wind-farm and also through the Dover Straits.

    “To complement these services, seven differential-Loran (DLoran) Reference-Stations, one located close to each of these survey areas have been established. These stations monitor the time of arrival of the received eLoran signals, and generate differential-corrections that are broadcast via the Anthorn Loran Data Channel (LDC), to account for temporal variations in these ASF maps.

    “Making use of these ASF maps, combined with the locally-produced differential corrections, can allow a maritime user of eLoran IOC to obtain position accuracy of the order of 10m (95%), within a radius of 30 to 50 km of the DLoran reference station.”

    See also “Back-up to Vulnerable GPS Signals Required for Busy Shipping Lanes.”

    The GLA authors conclude that:

    1. eLoran can deliver Resilient PNT and this has been demonstrated on several vessels.
    2. Seamless handover from primary (GPS) to secondary (eLoran) positioning source has been successfully implemented.
    3. Surveying and mapping of ASF has been carried out for several major ports and the required levels of performance demonstrated.
    4. DLoran reference stations to correct for short-term, temporal variations have been installed and commissioned.
    5. Good levels of performance have also been demonstrated for coastal voyage phase away from the ASF surveyed areas.

    eDLoran in Rotterdam. The July 2014 issue of GPS World presented a cover story showing results of a newer version, enhanced differential Loran (eDLoran), yielding position accuracies of approximately 5 meters.

    vw-W

    eDLoran: The Next-Gen Loran

    Potential GNSS Back-up Improves to GPS-Level Accuracy

    A new enhanced differential Loran system demonstrates 5-meter accuracy not achievable by the current DLoran system, and requires less expensive reference stations. A prototype tested in Rotterdam’s Europort area uses standard mobile telecom networks and the Internet to reduce correction data latency — a key source of error — by one to two orders of magnitude.

    By Durk van Willigen, René Kellenbach, Cees Dekker, and Wim van Buuren

    Figure 12. The large ship symbol (grey) is derived from the GPS-RTK receiver of the Rotterdam pilots. The width of the ship symbol is 10 meters and the speed-over-ground was 11 kts. The red triangle is generated by the eDLoran receiver and remains between the required ± 5 meter limits for eDLoran.
    Figure 12. The large ship symbol (grey) is derived from the GPS-RTK receiver of the Rotterdam pilots. The width of the ship symbol is 10 meters and the speed-over-ground was 11 kts. The red triangle is generated by the eDLoran receiver and remains between the required ± 5 meter limits for eDLoran.
    Figure 13. The red track is based on raw eLoran data without any corrections. The transparent blue line is made by GPS-RTK and is widened to 10 meters giving the required ± 5 meter limits of eDLoran. The white line is output from the eDLoran receiver which stays within the borders of the 10 meter wide transparent blue line.
    Figure 13. The red track is based on raw eLoran data without any corrections. The transparent blue line is made by GPS-RTK and is widened to 10 meters giving the required ± 5 meter limits of eDLoran. The white line is output from the eDLoran receiver which stays within the borders of the 10 meter wide transparent blue line.

    The GLA authors from the UK give a perspective on the Rotterdam project, as follows:

    “A compatible system (eDLoran) has been developed for operation by ships’ pilots on the Europort approach to the Port of Rotterdam.

    “However, Loran is a regional system dependent on international collaboration. The 9 transmitters in northern Europe are operated by Denmark, France, Germany, Norway and the UK.

    “Both Norway and France have declared an intention to cease Loran transmissions at the end of 2015. Moreover, France intends to dismantle its Loran infrastructure in 2016. Arrangements for the commercial operation of the infrastructure are being investigated, but this depends on some form of regional agreement. The European Union appears to have no policy for resilient PNT, the European Radio Navigation Plan having twice been drafted but never published. The view seems to bee that the introduction of Galileo will achieve resilient PNT, which it will not.”

    And Elsewhere

    South Korea is implementing a national eLoran service, and it is understood that similar plans are being considered in Russia and China.

    Meanwhile, the U.S. Army is interested in eLoran PNT for the warfighter.

  • Will China Win the Automated Vehicle Race?

    Janice Partyka
    Janice Partyka

    By Janice Partyka

    The race for the automated vehicle is on. This time, it’s not about whether automotive OEMs or tech will own the vehicle. It’s a battle between Baidu, China’s web giant, and Google, and it isn’t clear who will win. Baidu has announced it will launch an unmanned car in the second half of this year. Despite speculation that Baidu will be working with BMW, Baidu hasn’t announced its automotive partner. The Baidu vehicle will provide the flexibility of some conventional controls, such as pedals, coupled with automation, unlike Google’s approach of being completely autonomous, without pedals and steering wheel.

    One of the most practical uses of artificial intelligence is in the automated vehicle, as cars need to recognize and sort images they “see,” and make quick safety decisions. In a recent TED talk, Chris Urmson of Google revealed a few of the unusual things that Google cars have had to process while driving. The cars have successfully encountered a woman in an electric wheelchair chasing a duck on the road and a child driving a toy car in the road. I wouldn’t be surprised if there are some even weirder encounters that Google is shielding us from.

    Artificial intelligence is critical to the automated vehicle. This year Baidu won a prestigious international artificial intelligence competition at Stanford, but was just stripped of its title and barred from competing in 2016. Apparently, the Baidu team broke the rules on how many tests they could run. In the competition, computers had to recognize and sort images and classify objects into 1,000 different categories. The teams were allowed to run a limited number of tests to train their programs on identifying objects. The Baidu team exceeded the limits by submitting their program using different accounts. In an article in the New York Times, Jitendra Malik, an expert in computer vision, compared the actions of the Baidu team to drug use during a sports competition. “If you run a 9.5-second 100-meter sprint, but you are on steroids, then how can your result be trusted?” Malik said.

    Automated vehicles aren’t the only location market Baidu is aggressively pursuing. With technology from IndoorAtlas, Baidu has rolled out indoor location to 270 million active users of its map application. The solution uses mobile device technology to create geomagnetic maps of indoor places to enable indoor search and to power store and product search, as well as way-finding. A physical map of a building is uploaded into an app on a mobile device, like a smartphone. Using the app, a person walks all corridors in a building, thereby adding location positioning and creating a map.

    Let’s return to the topic of automated vehicles. Earlier this month, Uber suffered a blow when the California Labor Commissioner’s Office ruled that drivers are employees and not contractors, and therefore need to be so compensated. Taxi and limo services had been hurt by services like Uber, and they pressed for redress from what they felt was unfair competition.

    Like Uber, the automated vehicle market will likely hit intense push-back from a number of industries that will be disrupted. These include insurers, taxi and truck drivers, and personal injury and traffic litigation attorneys. These groups may try to build regulatory roadblocks for automated vehicles. And as their businesses may suffer, the automated vehicle industry needs to think now about how to mitigate the damage and create allies. With a completely different political process, Baidu may encounter no such resistance in China — quite an advantage. Perhaps Baidu will be first out of the gate, but may not be the long-term winner. Think Ford Sync.

     

  • Singapore Joins with China to Develop Apps, Protect BeiDou Signals

    Singapore and China are jointly opening a center to develop applications for the BeiDou GNSS, according to a report in Space News. The nations also have signed a commercial agreement to create anti-jamming systems to protect BeiDou signals.

    At a briefing during the CommunicAsia show held in Singapore May 31-June 2, SpaceTime Technology Pte Ltd. and ST Electronics (Satcom & Sensor Systems) Pte Ltd. signed a memorandum of understanding to “develop in Singapore an interference-resistant Beidou satellite positioning system,” SpaceNews report.

    The companies said the goal is to protect BeiDou signals from unintentional jamming in urban environments, where wireless devices occasionally overstep their radio-frequency boundaries.

  • As June 30 Nears, Leap Second Looms

    Leap-Second-O

    The world’s clocks will be adjusted by one second on June 30, when a leap second will be inserted into Coordinated Universal Time (UTC), the standard international time scale.

    In theory, all UTC clocks should insert a second labeled 23h 59m 60s (the leap second) following one labeled 23h 59m 59s UTC. This is equivalent to having all of the clocks in the world stop for one second at that time, as explained in May’s Expert Advice column.

    Several legacy GPS receivers immediately and incorrectly applied a leap second correction as early as January, or showed incorrect leap-second-pending data when queried due to an incorrect interpretation of the GPS specification by the firmware programmers of those GPS receivers, according to Jackson Labs Technologies.

    To help affected industries prepare, the DHS National Coordinating Center for Communications issued guidance with a paper titled “Best Practices for Leap Second Event Occurring on 30 June 2015.”

    The financial market has prepared for potential disruptions. The adjustment could present technical difficulties for traders and exchanges, as some computers might not be programmed to account for the adjustment.

    One company preparing is Racelogic, who makes the LabSat simulator. Racelogic will be recording the leap second as it happens and will then have the scenarios available for customers to replay. A variety of recordings will be taken: GPS, GLONASS, and BeiDou constellations will each be captured as a single channel, and also as a simultaneous triple-constellation recording. These will then be available to use with the LabSat.

    Jackson Labs has released new firmware versions for various products that address any potential issues for the pending and future leap second events, and that add a number of additional commands to query and handle leap second events.

    Precise Time and Frequency, Inc., has published a paper, “Phase Error Correction — Precision versus Speed,” which describes a technique for rapidly eliminating very large phase offsets (up to 0.5 seconds) between two 1 pulse per second pulses. The change is achieved without a sudden step change (which can be unwelcome in numerous applications) while retaining the ability to tune the phase with high precision (resolution of 0.006 pico seconds) once the large error is eliminated.

    “Like many novel ideas, the simplicity of this technique belies its effectiveness,” according to the paper. “With hindsight it seems like an obvious solution; however, the engineering mind is trained to know that to generate a one-second pulse from a reference frequency (in this case 10 MHz), it must be divided by the frequency itself, and the concept of an ‘incorrect’ divisor is not necessarily so obvious. In this case, however, the technique provides an ideal solution that reduces the phase-lock capture time from something that would be intolerable to a very acceptable time period.”

    Download the paper at this link.

  • LabSat’s SatGen v3 Adds BeiDou to Simulator Scenarios

    LabSat’s SatGen v3 Adds BeiDou to Simulator Scenarios

    Photo: LabstatSatGen v3 software is now available for the LabSat GNSS simulator by Racelogic. Version 3 includes BeiDou (BDS) in addition to GPS and GLONASS.

    SatGen is billed as a powerful and intuitive software package that gives users the ability to create scenarios for replay through any LabSat simulator. The software creates either user-generated or imported trajectory files for use with a LabSat simulator.

    The addition of the BeiDou B1 signals means that users can now test a device’s effectiveness as if it were being used within the operating area of the Chinese constellation, which at present only provides full coverage in Asia.

    The BeiDou constellation is set to become globally operational by 2020. With the new SatGen v3, users can create scenarios that include signals from satellites yet to be launched, so new products can be developed in readiness for the full constellation.

    SatGen v3 can produce scenarios with one, two or three sets of signals being simultaneously output: GPS, GLONASS and now BeiDou. The software now matches the record and replay abilities of the LabSat 3 simulator.

    A trial of SatGen is available here. To purchase a full copy contact a LabSat distributor.

    The LabSat 3 GNSS simulator.
    The LabSat 3 GNSS simulator.
  • NovAtel G-III Reference Receiver Technology Chosen for QZSS

    NovAtel G-III Reference Receiver Technology Chosen for QZSS

    The NovAtel G-III receiver.
    The NovAtel G-III receiver.

    NovAtel Inc. has entered an agreement with NEC Corporation to supply reference receiver products for use in the Quazi-Zenith Satellite System (QZSS). QZSS is Japan’s regional satellite-based augmentation system.

    The NovAtel receivers to be used by QZSS are based on the company’s third-generation (G-III) family of reference receivers. Designed for integrity monitoring and reference measurement applications, the receivers track signals independently to provide precise code- and carrier-phase reference measurements as well as signal quality measurements and other integrity monitoring metrics. Housed in a 19-inch rack-mount enclosure with AC power supply and integral cooling fans, the G-III reference receivers provide continuous, reliable operation in a reference station environment, NovAtel said.

    The G-III receiver platform has been customized to meet the needs of individual satellite networks. In addition to the QZSS G-III product, NovAtel supplies WAAS G-III reference receivers to the U.S. Federal Aviation Administration’s (FAA’s) modernized Wide Area Augmentation System (WAAS) network and IRNSS G-III reference receivers for the ground control segment of the Indian Regional Navigation Satellite System (IRNSS).

  • UNB’s PPP Software Centre v2.0 Beta Now Available

    The PPP Software Centre, an email-based Online PPP comparison utility hosted by the University of New Brunswick, is once again functioning with its release of version 2.0 Beta following an extended hiatus while being rewritten.

    The centre is a convenient method for the GNSS community to compare results from several online precise point positioning services. For a more detailed description, including submission instructions, see the homepage at http://www2.unb.ca/gge/Resources/PPP/.

    Note that the report has changed slightly, adding additional features, including final static position estimates tabulated in both Cartesian and geodetic coordinate systems; the name of the Cartesian system (and its epoch); and featuring a so-called Subject Line Interface, allowing advanced users some additional control over the centre’s behavior. This last feature may see some future expansion.

    The centre invites feedback on the utility.

  • Raytheon Demonstrates Advanced GPS OCX Capabilities

    On June 3, Raytheon demonstrated the advanced capabilities of the GPS Next Generation Operational Control System (GPS OCX) to key U.S. Department of Defense  (DoD) and other stakeholders through a series of realistic operational demonstrations.

    The demonstrations, which incorporated software that will be delivered with the Launch and Checkout System, validated how automation will improve system efficiency and effectiveness.

    GPS OCX is the ground-based command and control system that will manage GPS satellites with significantly improved accuracy and precision, while providing unprecedented levels of cyber protection.

    “These successful demonstrations incorporating actual GPS OCX software reflect Raytheon’s significant and continuing progress on this program and the growing maturity of this very complex system,” said Dave Wajsgras, president of Raytheon’s Intelligence, Information and Services. “Once delivered, this pathfinding, cyber-hardened ground system will significantly enhance the capabilities GPS brings to military, civil and commercial users worldwide,” said Wajsgras.

    The demonstration provided DoD and other stakeholders with a look at how OCX will automate many tasks currently performed manually, resulting in reduced opportunities for error and increased operational tempo for delivering military and other applications, Raytheon said.

    Raytheon demonstrated the benefits of OCX in providing new high-power, jam-resistant military signal known as M-code, as well as the system’s unprecedented cyber automation, detection and response capabilities.

    Raytheon is installing the Block 0 Launch and Checkout System (LCS) hardware at Schriever Air Force Base. LCS software, which includes the cyber-hardened infrastructure for OCX Block 1, is in the qualification test phase and is on track for delivery in mid-2016.

  • ION Co-Locates ITM, PTTI Conferences for 2016

    Two of the Institute of Navigation’s (ION’s) conferences — the International Technical Meeting (ITM) and the Precise Time and Time Interval (PTTI) Meeting — will be co-located for 2016. One registration fee gives attendees access to both technical events and a commercial exhibit. The co-located conferences will take place Jan. 25-28, 2016, at the Hyatt Regency Monterey in Monterey, Calif.

    Abstracts are due Oct. 2, 2015. Submission requirements have changed, and depend on the session the abstract is submitted for. Review the call for abstracts for more information.

    This year’s joint ITM/PTTI Plenary Session is “Autonomous Vehicles – Beyond the Navigation Technology.” The session will address issues outside of navigation technology, including legal issues, regulatory challenges, transitional periods, markets enabled by autonomous operation and similar topics beyond the core navigation technology.

    ITM is ION’s winter meeting, which features peer-reviewed technical papers related to positioning, navigation and timing, and includes the ION Fellows and Annual Awards presentations.

    PTTI is the annual technical conference designed to disseminate and coordinate PTTI information at the user level, review present and future PTTI requirements, inform government and industry engineers, technicians and managers regarding precise time and frequency technology and its problems, and provide an opportunity for an active exchange of new technology associated with PTTI.

    The co-located 2016 ITM and PTTI meetings will feature a technical exhibit and showcase of products and services related to positioning, navigation and timing. For more information on exhibiting, contact ION or go to www.ion.org.

  • European GNSS R&D: There’s an App for That!

    European GNSS R&D: There’s an App for That!

    Cover: European GNSS AgencyA free app for both iOS and Android features the results of European GNSS Agency (GSA) supported research and development initiatives. The new EGNSS Research and Development (R&D) application highlights the tangible results coming out of the 7th Framework Programme (FP7) and is designed to serve as inspiration for those participating in the Horizon 2020 (H2020) period.

    The FP7 and H2020 programs, supported by the GSA, aim to support the development of EGNSS applications in key market segments. Both are geared towards accelerating the development of a European market for satellite navigation applications and creating new opportunities for European industry.

    “The app is an excellent opportunity for the GNSS community to take stock in the lessons learned during the FP7 funding period and set our sights on future R&D initiatives,” said GSA Executive Director Carlo des Dorides. “The application’s segment-specific search feature responds to the varied needs of our users, providing them with easily accessible and relevant information at their fingertips.”

    In addition to the search function, des Dorides notes that the demographics included with each project can help users identify opportunities for partnerships across segments and regions, and create virtual R&D networks.

    The FP7 programmes had a considerably positive impact on the GNSS market, GSA said (download the brochure). Within the frame of the projects, 45 products were developed, and 80 prototypes were tested and validated during the 115 demonstrations that took place.

    Today, Horizon 2020 is bringing new opportunities for GNSS applications development. Information on the 25 projects granted in the first H2020 Galileo call is already included in the application, and early next year it will be updated to include the 2nd call portfolio of projects.

    The app is available for free download from the iTunes and Google Play stores.