Tag: WAAS

Review benefits of GNSS rover accuracy
Douglas County Public Works needed a GNSS rover to support its UAS operations. The pay-as-you-go option was appealing as they only needed high-precision a few times per month. (Image: Jason Schilling)

This is part II of our III part feature story. Check out part I, Minnesota company develops new system for mapping underground utilities and part III, Robotic total stations add scanning capabilities.

High precision GNSS rovers play a vital role in a broad variety of field surveying and mapping applications. Different users have different value propositions in mind when choosing field hardware and software: expected precision, sources of corrections, configurations for specific workflows, and, of course, cost. Weighing these many considerations, GNSS manufacturers have come up with portfolios of multiple models to fill these varied needs.

That said, GNSS manufacturer Bad Elf took a different approach when it designed its flagship rover, the Bad Elf Flex. The Flex is designed to meet the cost-precision-workflow needs of everyone, from asset mappers to surveyors. (Hence the name “Flex.”) To inform the design of the Flex, Bad Elf listened to field users who wished for a scalable solution in a single rover, rather than having to buy multiple different models, and without breaking the bank.

Options for the Infrequent User

“I had one of the little Bad Elf GNSS surveyor handhelds for many years,” said Jason Schilling, wildlife biologist with Douglas County Public Utility District in central Washington State. “That worked great for rough mapping, between a foot and a meter of precision, and I could connect it via Bluetooth to mapping software on my mobile.”

But this all changed when Schilling began an unmanned aerial system (UAS) program for the utility several years ago.

“I really needed survey-level precision for ground control points to geolocate the images from the UAS,” said Schilling.

He was aware of the high cost of centimeter-precision-capable surveying rovers and it was too big of an investment, considering that he only did UAS mapping a few times a month. As an existing Bad Elf customer on the company mailing list, Schilling learned about the new Flex rover, which offered multiple options, and he found one that seemed quite enticing for the needs of his utility.

Schilling purchased a Flex Standard bundle at a low base price, about $3,000, with the pay-as-you-go plan for high precision. In the standard configuration, the Flex is capable of autonomous positioning (1–5 m), and mapping grade (sub-meter precisions) via free satellite-based augmentation services (SBAS), such as WAAS. But when the user activates a pre-purchased “token,” the full centimeter-precision capability, using external corrections, is enabled.

“On the day of a UAS survey, we turn it on, activate a token from our account, and then we have 24 hours of high precision,” Schilling said. “It costs us $25 per day.”

For two to three UAS surveys a month, this works out to far less over many years than the cost of buying a typical surveying rover.

Correction Sources

For real-time kinematic (RTK) corrections, Schilling connects via NTRIP to the statewide cooperative real-time network (RTN); sometimes in a network RTK mode (such as VRS) or single-base RTK to a nearby reference station on the same network. The Flex accommodates NTRIP connections to RTN or IP-enabled reference stations, but Bad Elf has added even more flexibility for corrections.

In some scenarios there is no access to an RTN or no cell service (needed for NTRIP access). One option in these cases is to add a second Flex, set it up as an RTK base, and connect the base and rover via radios that Bad Elf offers.

Bad Elf has added other options for corrections: the Bad Elf RTK service taps into a nationwide real-time network operated by Point One Navigation. This is accessible via NTRIP in the same manner as regional, state or local RTN, and is offered for a monthly fee. In addition, for situations where there is no RTN or cell service, a global precise point positioning (PPP) service (Atlas) can be enabled on the Flex.

PPP differs from RTK/RTN in that it does not need the dense arrays of reference stations, or cell service to access. Instead, PPP derives very precise clock and orbit data from a global array of tracking stations and delivers this to the Flex via geostationary satellites. After a short convergence time, PPP from the Atlas service will yield 5 –10 cm precision over most of the globe.

The Full Boat

Full Configuration. Brian Cortese works for the City of Ellensburg, where he uses the FLEX Extreme Bundle for multiple field applications. (Image: Brian Cortese)

The City of Ellensburg, a college town and farming community in central Washington State, chose the Flex Extreme bundle for about $6,000 — the “full boat” configuration. The Extreme bundle enables all the add-on services all the time, eliminating the need for tokens. In their case, the frequency of use made the higher initial investment worthwhile.

“We have big plans for our rovers,” said Brian Cortese, Engineering Tech/Inspector for the City of Ellensburg Public Works & Utilities.

Ellensburg is a vibrant town that is attracting a lot of new development and it is being proactive in surveying and mapping assets as they are added or replaced.

“We’re recording manholes and valves, sewer systems, storm water systems, irrigation, hydrants — everything that gets built in the city gets as-built surveyed,” Cortese said. “Precise, real-time positioning, it’s been a benefit to us already. We can go out before they work on the subgrade for new developments and take measurements, and then when they finish the subgrade and pave it, we can go back and locate those exact positions.”

Ellensburg uses corrections from the statewide cooperative RTN. In fact, one of the RTN reference stations —also part of the NOAA National CORS Network — is right in the center of town atop the science building of Central Washington University. While the city does a wide variety of surveying and mapping, with the Flex and RTN corrections surveyors get the same centimeter-precision for everything they measure in the field.

“We’ve done design projects with it,” Cortese said. “For instance, we recently took measurements in an area of downtown for a proposal by recording positions and elevations to develop a new park and entertainment area for the community. We are also marking Americans with Disabilities Act (ADA) ramps to meet federal specs out in the field — it’s been really handy for so many things.”

Survey-Grade Rover

To serve the full range of precision needs, the Flex had to be designed as a survey-grade rover. It has a full-constellation GNSS and RTK engine: GPS, GLONASS, Galileo, BeiDou, and support for other regional constellations. With more satellites in view, it can perform in sky-view-challenged locations, such as around buildings and under tree canopy.

“Ellensburg is on the Tree City, USA list; our streets are very well lined with a variety of trees, which is also where a lot of our utilities are and development is going on,” Cortese said. “We have been able to get good precisions in and around those trees. Actually, someone on our staff is taking an inventory of the trees with the Flex and loading the data directly into ArcGIS.”

Even in the more rural areas of Grant County that enjoy a lot of open sky, Schilling said, some areas planned for mapping are along upper tributaries and in the hills with a lot of tree coverage. He said the Flex has performed well in those areas.

Choices

The Flex offers these options and combinations:
- Flex Extreme. Full survey-grade rover that can use a variety of correction types.
- Base-Rover RTK. Two Flex Extreme units connected via radio.
- External RTN/RTK corrections via NTRIP.
- Bad Elf RTK Service. Single-tap access to a nationwide RTK corrections service.
- PPP service. Atlas PPP corrections via L-band geostationary satellites.
- Flex Standard. Pay-as-you-go high-precision-enabled service using tokens.
- Static Logging. Observation file logging for post-processing (supported by Flex Extreme).
- Compatibility with multiple field-mapping software applications.
While many modern GNSS rover systems support one or more options similar to those listed above, Bad Elf’s Flex supports all of them, making it capable of a wide variety of applications.
February 22, 2023
What happened to GPS in Denver?
Photo: YayaErnst/iStock/Getty Images Plus/Getty Images

Something big happened to GPS service in the Denver area on Jan. 21.

On that day, Air Traffic Control issued a notice advising pilots of problems with GPS reception spanning about 8,000 square miles in the Denver area.

The advisory, posted at 10:33 p.m. Denver time, said GPS was unreliable within a 50-nautical-mile radius of the Denver International Airport. Interference was likely to be experienced by aircraft on the ground and as high as 40,000 feet above sea level.

The advisory also said the Wide Area Augmentation System (WAAS) and Ground-Based Augmentation System (GBAS), both designed to make navigation with GPS more precise, as well as the ADS-B collision avoidance and traffic management system, would be unreliable.

Pilots reported other systems affected such as transponders that help radar controllers keep track of aircraft, traffic alert and collision avoidance (TCAS) equipment, autopilots, electronic flight bags and terrain warning systems.

Pilots trying to land at Denver International and the much small Centennial Airport 20 miles to the south reported a variety of problems.

From the social media platform Reddit:

I flew in there (Centennial Airport) last night and I’m about to fly out. One second everything was fine, and then next second we completely lost GPS for the rest of the flight, probably coming through ~14,000 [feet] on the arrival from the northwest.

In addition to verbal reports to air traffic controllers, formal reports were filed with NASA’s Aviation Safety Reporting System (ASRS) by pilots flying into Denver International. (Note that ASRS only lists the month reports were submitted, not the day, to preserve anonymity.) Nineteen ASRS reports about GPS in Denver during January match well with comments on Reddit and an Airliners.net forum for the 21st and 22nd of the month.

The ASRS reports tended to focus on problems during approaches to the airport and landings. The most minor included distracting cockpit alerts and warnings.

Cleared ECAM (Electronic Centralized Aircraft Monitor) and emergency cancelled the repetitive nuisance messages. Additionally, received a GPS Lost message on FMC [Flight Management Computer].

More concerning were incidents that could more directly impact safety of flight.

One aircraft’s collision avoidance system, which normally reports issues as they develop, abruptly directed action to avoid another aircraft.

…we received a “LEVEL OFF” TCAS RA with no prior notification. The offending target was to our 2-3 o’clock and climbing…

Two aircraft reported confusing navigation displays on final approach to the airport. One pilot flying in limited visibility (instrument conditions) was sufficiently concerned that they aborted a landing attempt at the last minute.

We were about 1000 AGL [1,000 ft above ground level] – not sure about the exact altitude – and our RA [anti-collision warning] turned into an amber color… We were about 300 – 200 AGL and our autopilot failed… It was very unexpected… I called the go-around.

So, what happened to GPS?

At first, Air Traffic Control told pilots 5G telecommunications systems were causing the interference. That stopped at some point, though, according to an online comment:

As a [air traffic] controller… they haven’t told us anything. I was at work when it all started yesterday and they told us to make broadcasts about 5G interference. Today, they said it wasn’t 5G and not to make those broadcasts, but they still haven’t said what the issue is. There’s obviously rumors and speculation, but at this point, nothing concrete.

The first mention of the incident in traditional media seems to have been in an August 2022 journal article by a group of researchers at Stanford University. It focused on using the aviation ADS-B system to geo-locate GPS interference. The U.S. Department of Transportation provided the exact location and signal strength of Denver’s interfering transmitter to assist the Stanford study.

Requests in August and early September to the departments of Transportation, Homeland Security and Defense for more information on the incident went unanswered.

The picture became a bit clearer, though, on the second day of the Civil GPS Service Interface Committee (CGSIC) held (coincidentally) in Denver.

Mike Roskind from the Department of Homeland Security (DHS) provided some information and promised a formal report would be forthcoming. He said:
- the incident lasted for 33.5 hours
- impacts varied across infrastructures and applications; some users who were physically shielded from the interference source were able to maintain service
- wireline and cellular providers had timing backup systems and were unaffected
- a radio system with no backups suffered, as did a simulcast radio system that used rubidium backup clocks; the clocks drifted away from each other over the course of the outage and caused towers to isolate.
Responding to a question about the source of the interference, Roskind confirmed that 5G telecommunication was not the cause, but refused to say more.

He also declined to identify other systems, applications and infrastructure impacted by the disruption. He said that the department is very concerned about protecting the identity of affected users cooperating with the government analysis.

More information will be provided in a DHS report on the incident titled “GPS Interference Happens.” The report is in final review now, according to Roskind, and is expected to be released in October.
September 21, 2022
Raytheon awarded FAA contract to upgrade WAAS to dual-frequency

WAAS makes airports without ground-based navigation available to pilots. (Photo: Raytheon)

WAAS monitors and evaluates all GPS signals over North America to enable pilots to fly using augmented GPS data for precision landing and enroute navigation

Raytheon Intelligence & Space, a Raytheon Technologies business, has been awarded a competitive indefinite-delivery, indefinite-quantity contract from the Federal Aviation Administration with a ceiling value of $375 million over the next 10 years.

Task orders, valued at $215 million, were executed at contract award to provide technical refresh and dual-frequency operation (DFO) upgrades to the FAA’s Wide-Area Augmentation System (WAAS) to provide safer air travel in support of the National Airspace System.

WAAS monitors and evaluates all GPS signals over North America to enable pilots to fly using augmented GPS data for safety-of-life missions such as precision landing and enroute navigation. The system allows pilots to safely land in places previously inaccessible because of the airport location or weather. It also makes airports without ground-based navigation available to pilots.

Under the WAAS DFO-2 contract, Raytheon will deliver more modern, and therefore sustainable, processing, system security, and network architecture, while also adding dual-frequency service.

“There is no margin for error during take-off, flight or landing,” said Denis Donohue, president, Surveillance & Network Systems at Raytheon Intelligence & Space. “Our modernization effort for WAAS will improve system robustness during ionospheric events and ensure safety-of-life requirements continue to be met.”

WAAS is a satellite-based augmentation system (SBAS) that provides GPS corrections for critical navigation for the aviation community, first responders and other government agencies, ensuring pilots can land safely in austere environments, despite weather challenges. It also provides corrections for SBAS-capable receivers in use across a diverse set of communities, including agriculture, maritime and surveying, among others.

Raytheon Technologies has been the prime development contractor for WAAS since 1996. Since reaching initial operational capability in 2003, Raytheon and the FAA have developed and fielded dozens of enhancements expanding WAAS’ precision approach capability, coverage area, and reliability, including improvements to the system infrastructure in preparation for dual-frequency service.

WAAS dual-frequency service will enable increased system accuracy, integrity and availability when subject to ionospheric perturbations, including solar storms. Work for this effort is based in Fullerton, California.

September 17, 2022
GPS/GNSS industry recollections and predictions from the GPS World Editorial Advisory Board

Members of the GPS World Editorial Advisory Board share their memories and thoughts about the GPS industry over the past 30 years.

Find out what they had to say.

• Stuart Riley: GPS: Obscurity to ubiquity
• John Fischer: Modern miracle brings timing to the ‘Information Superhighway’
• Terry Moore: Transiting to GPS and beyond
• Ellen Hall: History of the GNSS industry and milestones ahead
• Jules McNeff: GPS and GNSS: confronting dual-use realities
• Miguel Amor: Four decades of leadership
• Julian Thomas: From racecars to boundless opportunities
• Alison Brown: NAVSYS’ role in WAAS
• Ismael Colomina: Discovering a new GPS journal
• Greg Turetzky: Putting GPS in smartphones
• Clem Driscoll: The evolution of GPS
• Mitch Narins: What it means to be a Gold Standard
• F. Michael Swiek: Behind GPS is the people

Feature image: Smithsonian; Charlie Trimble provides the 4000A GPS Locator to the Smithsonian Museum. Introduced in 1984, the Trimble 4000A was the first commercial GPS positioning product.

October 16, 2020
NAVSYS’ role in WAAS

Alison Brown, president & CEO, NAVSYS Corporation

Thirty years ago, NAVSYS was deep into the development of the Wide Area Augmentation System (WAAS). I had the honor of being the chair of the RTCA SC-159 Integrity Working Group, which developed the first concepts for what evolved into three integrity standards for GPS: multi-sensor integration, receiver autonomous integrity monitoring (RAIM) and wide-area differential GPS using a GPS integrity channel (GIC) to broadcast corrections over a geostationary overlay.

NAVSYS, working with Inmarsat Corporation, built the first prototype WAAS SIGGEN equipment, which was deployed at the Coonhilly Coast Earth Station and used to transmit an L-band C/A-code signal over the Inmarsat Atlantic Ocean Region MARECS-B satellite to a software GPS receiver that we had developed and installed at Inmarsat’s Test and Development Laboratory in London.

First Inmarsat Geostationary Overlay Test-Bed, 1991. (Image: NAVSYS)

Image: FAA

This evolved into the FAA’s WAAS program, which used the NAVSYS SIGGEN for the initial deployment, test and evaluation. The algorithms developed by NAVSYS were ultimately licensed to Raytheon for use on the operational WAAS and MSAS systems.

October 5, 2020
Readiness confirmed for July 31 WAAS satellite launch

Approval is given for Arianespace’s Ariane 5 flight on July 31

Arianespace’s fifth mission of 2020 has been given the green light for liftoff following a July 29 launch readiness review conducted at the Spaceport in French Guiana.

The launch will deliver the Intelsat Galaxy 30 (G-30) satellite into orbit. G-30 will become part of the Wide Area Augmentation System (WAAS), the air navigation aid developed by the U.S. Federal Aviation Administration to augment GPS and GNSS.

Besides G-30, the Ariane 5 launch vehicle will also carry the Mission Extension Vehicle-2 (MEV-2) and BSAT-4b. All satellites are flight-ready, along with the Spaceport’s infrastructure and the network of downrange tracking stations.

With approval granted, Ariane 5 also is cleared for rollout on July 30 from its Final Assembly Building to the ELA-3 launch zone. Liftoff will occur on July 31 during a 46-minute launch window opening at 6:30 p.m. local time in French Guiana. To watch the launch live, visit the Arianespace website.

Ariane 5 will deliver a total payload lift performance of approximately 10,468 kg. on the mission to geostationary transfer orbit (GTO), which is designated Flight VA253. This total factors in the three passengers, plus the workhorse vehicle’s multi-payload deployment system and integration hardware.

G-30 and MEV-2 — both produced by Northrop Grumman to serve the operational needs of Intelsat — are stacked together in the upper position of Ariane 5’s payload configuration. G-30 will be deployed first during the 47-minute flight sequence, followed by MEV-2.

To be released last as the mission’s lower passenger, BSAT-4b is being launched by Arianespace as part of a turnkey contract between the Japanese operator B-SAT and the satellite manufacturer, Maxar.

July 29, 2020
Horizon realizes benefits of WAAS; Delta lands GLS approach in Dominican Republic

Horizon realizes benefits of WAAS

More than a decade ago, Horizon Air, a regional affiliate of Alaska Airlines, decided to implement the Wide Area Augmentation System (WAAS) as a part of its overall solution.

According to the Federal Aviation Administration’s (FAA) SatNav News winter 2020 newsletter, the airline has identified a number of benefits from implementing the WAAS, including pre-departure planning, enhanced safety and scheduled reliability.

“Our schedule reliability has become the best in our route structure due to the lowest possible approach minimums at airports Horizon Air serves,” said Perry Solmonson, Horizon Q400 check airman/flight ops duty officer.

Delta lands GLS approach in Dominican Republic

On Oct. 16, 2019, Delta 737 pilots, Captain Jon Hensler and Captain C.E. “Noah” Flood, along with 737NG Technical Manager Mike Mannino, conducted a GBAS Landing System (GLS) approach in Punta Cana, Dominican Republic. According to the FAA SatNav News newsletter, the GLS landing was a first for a North American carrier operating a revenue flight into Latin America.

The Punta Cana airport is the first Latin American airport with GLS capability. GLS approaches at this airport permit significantly lower operational weather minimums, allowing aircraft to safely operate into this airfield when they would otherwise need to divert.

According to the newsletter, the approach was the beginning of a several month Delta trial for GLS approaches at the Punta Cana airport.

Check out the full stories in the FAA SatNav News winter 2020 newsletter here.

April 24, 2020
Research Roundup: Focus on maritime

The 18,000-container-capacity CMA CGM Kuergelen. (Photo: CMA CGM)

Of the 273 papers researchers presented this year at the Institute of Navigation’s annual ION GNSS+ conference, which took place in Miami on Sept. 16–20, the following five focused on maritime issues. Papers are available at www.ion.org/publications/browse.cfm.

Automating the Sharing of Ocean Weather Data

The Automatic Identification System (AIS) — mandatory for large ships and used by many mid-sized ones — was designed to help avoid collisions, enable shore authorities to provide vessel traffic services, and allow coastal states to monitor their waters. It also may be used to transmit other information between AIS stations onboard and ashore.

In the aftermath of the sinking of the container ship El Faro in 2015, the U.S. National Transportation Safety Board (NTSB) and U.S. Coast Guard found a contributing factor was lack of reliable weather forecasts. The NTSB then recommended to the National Oceanic and Atmospheric Administration (NOAA) that it determine whether AIS could be used to share weather data collected by ships, to supplement the Voluntary Observing Ship (VOS) program where ships voluntarily submit weather observations to NOAA. The paper describes a successful test of this concept.

Citation. Gregory Johnson, Ken Dykstra, Gaurav Dhungana and Brian Tetreault, “Sharing Ships’ Weather Data via AIS.”

EGNOS for Maritime Navigation

The European Geostationary Navigation Overlay System (EGNOS), which has been providing guidance to civil aviation since 2011, also can support maritime, railway and road applications. This paper assesses its use for maritime navigation compliant with International Maritime Organization (IMO) requirements for harbor entrances, harbor approaches and coastal waters: 99.8% of signal availability, 99.8% of service availability, 99.97% of service continuity, and 10 meters of horizontal accuracy. A kinematic test campaign was conducted in the waters of the Canary Islands using a geodetic multi-frequency, multi-constellation receiver-antenna pair installed aboard two vessels. The EGNOS Maritime Service met all IMO requirements by achieving a signal availability of 99.999%, a service availability in 99.9% of a predefined rectangular region, and 1.06 meters of horizontal accuracy at the 95th percentile. The service continuity requirement, however, was met in only 62.50% of the predefined region. Therefore, the paper concludes that the continuity risk is the most limiting factor for expanding the EGNOS Maritime Service along the coastal waters of the Canary Islands.

Citation. Deimos Ibáñez Segura, Adria Rovira Garcia, Jaume Sanz, José Miguel Juan, Guillermo González Casado, María Teresa Alonso, José A. López Salcedo, Huamin Jia, Francisco Javier Pancorbo Garcia, Carlos Garcia Daroca, Irene Martin Calle, Santos Rodrigo Abadía Heredia and Manuel López Martínez, “A Kinematic Campaign to Evaluate EGNOS 1046 Maritime Service.”

Options for Integrity

Many maritime authorities are considering how to maintain the integrity of navigation systems as their infrastructure ages, especially given that the need for integrity in the user position is expected to increase with e-navigation services and for autonomous vessels. In harbor entrances, harbor approaches and coastal waters, the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) prescribes an absolute horizontal accuracy of ≤10 meters 95% of the time, with an integrity risk of 99.99999%. Today’s GNSS more than meets that accuracy requirement, so the driver is integrity. Options for integrity are marine radiobeacon DGPS/DGNSS, the primary augmentation system in use today; receiver autonomous integrity monitoring (RAIM); satellite-based augmentation systems (SBAS); and others (such as commercial services or inertial.). The European MarRINav project is investigating resilient PNT options to support UK Critical National Infrastructure. Part of this work is comparing EGNOS and marine radiobeacon DGPS performance to inform international discussions and receiver standardization.

Citation. Alan Grant, George Shaw and Martin Bransby, “Considering SBAS and marine radiobeacon corrections to support safe maritime operations.”

Evaluation of WAAS for Use in Canadian Waters

Mariners navigating in Canadian waters use a ground-based augmentation system (GBAS) that provides differential corrections and integrity monitoring of GPS. This GBAS has been provided since 1994 by the Canadian Coast Guard (CCG) in the form of a differential GPS (DGPS) broadcast service. The service is only provided south of latitude 60°N in collaboration with the U.S. Coast Guard. Before embarking on a recapitalization program of its 24-year-old DGPS, and given that the U.S. Coast Guard is progressively shutting down its National Differential GPS sites, the CCG is evaluating options for its own DGPS network. Options include the wide-area augmentation system (WAAS), originally developed by the U.S. Federal Aviation Administration for civil aviation. This paper describes the authors’ evaluation for the CCG to determine the expected accuracy, integrity and availability of WAAS throughout Canadian waters, concluding that the current WAAS provides acceptable accuracy and integrity for most of Canada, excluding the higher latitudes.

Citation. Gregory Johnson, Gaurav Dhungana and Jean Delisle, “An Evaluation of WAAS 2020+ to Meet Maritime Navigation Requirements in Canadian Waters.”

GNSS + INS for Attitude Determination

Attitude determination (AD) is an important navigation component for ships and spacecraft. GNSS enables resolving their orientation in a precise and absolute manner, by employing multiple antennas rigidly mounted on the vessel. This requires carrier-phase observations, with the consequent added complexity of resolving integer ambiguities. Inertial aiding has been extensively exploited for AD, because it enables tracking fast rotation variations and bridging short periods of GNSS outage. In this paper, the fusion of inertial and GNSS information is exploited within the recursive Bayesian estimation framework, applying an Error State Kalman Filter, which, unlike common Kalman filters, tracks the error or variations in the state estimate, posing meaningful advantages for AD. The results show that the inertial aiding, along with a constrained attitude model for the float estimation, significantly improve the performance of attitude determination compared to classical unaided baseline tracking.

Citation. Daniel Medina, Vincenzo Centrone, Ralf Ziebold, and Jesús García, “Attitude Determination via GNSS Carrier Phase and Inertial Aiding.”

January 15, 2020
NovAtel delivers signal generators to modernize FAA’s WAAS

Next-generation NovAtel ground uplink station signal generators delivered for SBAS modernization

Photo: NovAtel

Hexagon/NovAtel announced that shipments of next-generation ground uplink station (GUS) signal generators have commenced in fulfillment of its contract with the United States Federal Aviation Administration (FAA) to support the FAA’s safety of life wide-area augmentation system (WAAS) navigation service.

Developed by the FAA for civil aviation, WAAS is a safety-critical navigation aid that provides integrity monitoring and differential corrections for all phases of flight. The next-generation NovAtel GUS signal generator replaces the legacy product that has operated successfully for more than 15 years and ensures continued operation for years to come.

Along with the GUS signal generator modernization, the contract includes ongoing engineering support services for the complete portfolio of NovAtel ground reference receiver products deployed by the FAA.

“We have a long-standing relationship with the FAA and worked very closely with the WAAS program team to deliver this critical next-generation technology for SBAS modernization,” stated Jonathan Auld, NovAtel Vice President of Engineering and Safety Critical Systems. “We’re very pleased to continue our commitment to support the FAA and their safety of life WAAS service.”

January 7, 2020
A new era begins with geospatially based aviation

At any given moment, more than 5,000 airplanes are flying over the United States. In a single year, nearly 778 million passengers will take to the skies — more than twice the population of the U.S., and the number increases each year. Aviation is the safest form of transportation. It is 100 times safer than driving. For every 100 traffic deaths, only one aviation related fatality occurs; and the Federal Aviation Administration (FAA) is working hard to make aviation even safer.

Safety is the FAA’s primary focus. The FAA Strategic Plan FY 2019– 2022 states its mission is to provide the safest, most efficient aviation system in the world. To achieve this goal, the FAA is implementing several initiatives. The technical aspects of these efforts fall under a framework called NextGen designed to modernize the nation’s air traffic control system. NextGen began in 2003 in the VISION 100 – Century of Aviation Reauthorization Act. At its core, NextGen is a geospatial framework with satellite navigation as its backbone.

The Geospatial Data Act (GDA) became law when President Trump signed the FAA Reauthorization on Oct. 5, 2018. You might have wondered how the GDA came to be included in the bill. It makes sense in the context of technology advancements towards a smart transportation network, specifically in aviation.

The smart transportation concept integrates all forms of transportation to provide economic and environmental benefits as well as increase safety and reduce wait times and congestion. A large part of smart transportation is based on geographic information technology. The aviation component of this smart transportation initiative falls within the FAA’s authority under the overarching framework named NextGen.

NextGen is an integrated concept improving the efficiency and safety of flight operations both on the ground and in the air. The use of geospatial technology enables precision time-management for controlling air traffic. The system allows each airplane to digitally coordinate with other aircraft in the area, taking into account such things as terrain and other known hazards to safely reroute air traffic as necessary. The FAA refers to this as trajectory-based operations. Those with a knowledge of GIS will recognize it as four dimensional: it calculates direction, speed, distance and time relative to position in x-y-z, and coordinates that information with other known data. Additionally, the system uses historical flight data and predictive analytics to maximize airspace for routing air traffic such as what is experienced during the holidays.

NextGen also uses a system called Optimal Profile Descents (OPD), which allows an airplane to trim its engines and descend along a glide slope from flight level into the airport. The point at which a plane begins its descent is a geospatial calculation to determine the precise point in space for the airplane based upon its altitude, weight, glide slope and distance to the airport. The benefits of OPD are reduced engine noise, fuel savings, less carbon emissions and a positive economic impact. NextGen is an across-the-board win for the airline industry, airline passengers, the economy and the environment.

According to an interview with Michael Whitaker, former deputy administrator of the FAA who was the Chief NextGen Officer, NextGen revolutionizes aviation by enabling digital data communication. It replaces radar-based navigation and tracking with satellite-based air traffic control. The cornerstone of NextGen is the Automated Dependent Surveillance Broadcast (ADS-B) system.

ADS-B is an aviator’s version of Waze, but with a lot more information. ADS-B(out) broadcasts an airplane’s Flight ID, ICAO Code, speed and location in three-dimensional space to air traffic controllers and to everyone who is equipped with ADS-B(in). The combination of ADS-B(out) and ADS-B(in) greatly increases situational awareness for aviators. On Jan. 1, 2020, all airplanes operating in controlled airspace needed to have ADS-B(out) installed. ADS-B transforms the entire National Airspace System into a satellite-based geospatial network. It integrates multiple sources of real-time data, such as weather, pilot reports, aircraft positions, 3D airspace information, and other sources of data, which can be overlaid on top of various basemaps and terrain elevation models, allowing pilots to make more informed and safer decisions.

Switching to ADS-B opens up more capacity in already crowded skies by decreasing the required vertical and horizontal separation distances between aircraft. At Hartsfield-Jackson International Airport, the busiest airport in the world, changing to performance-based operations allowed 8 to 12 more departures per hour; and in Memphis International Airport, one of the busiest airports for cargo operations, arrivals increased by 20%.

Rune Duke, senior director of government affairs, Airspace, Air Traffic and Aviation Security for the Aircraft Owners and Pilots Association (AOPA), said that ADS-B will allow much faster update rates for air traffic controllers on the order of once every second, compared to legacy radar systems that report positions every 8 to 12 seconds. For an airplane traveling at 350 knots, that is about 1 mile. A lot can change in a mile in densely packed airspace.

If you are reading this because of your love of maps and aviation, then I highly recommend the FlightAware and ForeFlight smartphone apps. FlightAware turns the phone into an ADS-B(in) receiver showing the location and flightpath of each aircraft in the immediate area on a basemap. I sit on my back deck and watch airplanes coming and going because I live under the flightpaths for Dulles International Airport, Reagan International Airport, Leesburg Executive Airport, the Montgomery County Airpark and the TERPZ waypoint. On occasion I see helicopters flying to Camp David because I am under that flight path as well.

So, I get to see a variety of aircraft. You can select the airplane icon to see information such as aircraft type, airline, Flight ID, departing and arrival airports, altitude, and groundspeed. Even more information is available by selecting the pop-up window. This is ADS-B information. ForeFlight, on the other hand, is a pilot’s flight bag on a tablet.

In the future, ADS-B will integrate Aircraft Hazardous Areas (AHA): temporary no-fly zones due to commercial space launches. Because of ADS-B, planes will automatically reroute around the AHA, and when the AHA expires, airplanes will be routed back through the area.

ADS-B supports evolving technologies such as remote towers, another significant change to air traffic control. Remote towers allow air traffic controllers to be at a location other than the actual airfield. Remote towers use a suite of sensors mounted at the airfield, including high-definition video, thermal and night vision that can be combined with the digital information provided by ADS-B, all of which is displayed on widescreen panels in a room duplicating the experience of being at the airport and directing aircraft. This allows smaller airports that cannot afford the huge expense of building and staffing an air traffic control tower to be part of a remote tower network. One remote tower center will be able to support several airfields. Leesburg Executive Airpark recently finished successful testing of one of the first remote tower operations in the United States.

“Over the next 10 years, we are going to see logistics and transportation open up, from being limited by currently rigid road infrastructure to operating on fully flexible and responsive aerial transportation networks,” said Patrick Watson, director of business development for Animal Dynamics.

The envisioned Platform Unmanned Cargo Aircraft. (Photo: PUCA)

ADS-B will also support the integration of unmanned aerial systems (UAS) into the airspace, specifically unmanned cargo aircraft (UCA). In the not too distant future, carrier air fleets without pilots or aircrew will be taking to the skies. UCAs do not require crews, so there will be no need for water, toilets, sewage containment, kitchens or a cockpit (in the traditional sense). Taking those out will allow for more space in the plane to carry cargo and fuel. Plus, without crews on board, there will be no time restrictions on crew hours — planes will be able stay aloft longer and travel further. ADS-B greatly enables the success of this technology.

January 6, 2020
U.S. Navy to conduct GPS interference tests off Savannah
CSG4 19-03 GPS interference testing. (Image: FAA)

A U.S. Navy exercise in the southeastern United States will involve GPS interference testing that could make aircraft navigation unreliable or unavailable on Aug. 30 and Sept. 5.

The Federal Aviation Administration issued an advisory about the testing, which will be centered in the Atlantic off the coast of Savannah, Georgia, on the SAV VOR 139-degree radial at 84 nautical miles.

It could affect GPS reliability — including WAAS, GBAS and ADS-B — centered at 311230N 0795830W (SAV139084):
- within a 352-nautical-mile radius at Flight Level 400
- within 307 nautical miles at Flight Level 250
- within 242 nautical miles at 10,000 feet
- within 197 nautical miles at 4,000 feet above ground level
- within a 127-nautical-mile radius at 50 feet above ground level.
The tests are scheduled for 1800 Zulu to 2200 Zulu on Aug. 30, and 1600 Zulu to 2000 Zulu on Sept. 5.

The FAA advisory states that GPS interference notices to airmen may change with little or no notice, and encourages pilots to check regularly for updates. NOTAMs will be published at least 24 hours in advance of any GPS tests.
August 30, 2019
Garmin launches GNC 355 GPS/comm radio with LPV approaches

The GNC 355 is a GPS navigator with localizer performance with vertical (LPV) approach guidance and a built-in communications radio. (Photo: Garmin)

Garmin International Inc. has launched the GNC 355 — a GPS navigator with Localizer Performance with Vertical (LPV) approach guidance and built-in communications radio.

With the GNC 355, pilots can take advantage of the benefits of WAAS/SBAS GPS guidance, while also incorporating a modern comm radio into their existing avionics stack.

Intended for Class I/II aircraft that weigh 6,000 lbs./2,721 kg. or less, as well as experimental/amateur-built (EAB) aircraft, the GNC 355 Supplemental Type Certification (STC) is imminent and will be available in August for more than 700 aircraft makes/models.

“Based on the popularity of legacy products like the GX 60 and the GNC 250/300XL, as well as customer excitement for our new GPS 175 and GNX 375, we’re pleased to bring the GNC 355 to market,” said Carl Wolf, Garmin vice president of aviation sales and marketing. “The GNC 355 gives value-minded customers a simple upgrade path to a GPS navigator with a number of capabilities including WAAS/LPV approach guidance, wireless connectivity, a modern Comm radio, and with its standard mark-width form factor, pilots can easily add the GNC 355 without overhauling the panel of their aircraft.”

Aircraft owners can incorporate the GNC 355 into an existing avionics stack because of its standard 6.25-inch wide by 2-inch tall design. A vibrant, colorful and responsive touchscreen display boasts a familiar Garmin user experience, while a dual concentric knob and home button offer added versatility when interfacing with the touchscreen.

The user interface has been optimized for the screen size of the display, while also retaining a familiar menu structure similar to other Garmin products. Pilots can quickly access direct-to functionality, moving map, flight plan, nearest, procedures, waypoint and terrain pages, as well as frequency information using the touchscreen, and create customizable data fields and shortcuts for quick, one-touch access to important information.

Fully WAAS/SBAS IFR-approach-capable, the GNC 355 gives pilots the benefit of flying LPV, as well as Area Navigation (RNAV) approaches. Many approaches offer vertical approach guidance as low as 200-feet above ground level (AGL).

Pilots can also leverage the touchscreen and moving map to generate customized holding patterns over an existing fix in the navigation database or over a user-defined waypoint and easily insert it into a flight plan. Visual approaches are also available within the GNC 355 and provide lateral and vertical approach guidance in visual flight conditions.

Two versions, the GNC 355 and GNC 355A, are available with 25 kHz and 8.33 kHz frequency channel spacing respectively. Using the internal frequency database, airport, weather, Air Route Traffic Control Center (ARTCC) and Flight Service Station (FSS) frequencies are easy to find and can be loaded to the standby position by selecting the frequency from the airport information page. Recent, nearby and saved frequencies also offer easy access to frequency information. For example, with built-in standby frequency monitoring, pilots can listen to ATIS while monitoring tower frequency simultaneously. The airport identifier and frequency type are also displayed below the frequency so pilots can communicate with confidence.

An array of interface options includes the G3X Touch flight display for experimental and certificated aircraft, the G5 electronic flight instrument, the GFC 500 and GFC 600 autopilots, as well as select third-party autopilots. Course deviation and roll steering outputs can also be coupled to the GFC 500/GFC 600 autopilots and select third-party autopilots so procedures such as holds, radius-to-fix (RF) legs and missed approaches may be flown using the autopilot. Aircraft owners can also retain many of their existing flight instruments, audio panels and many legacy CDI/EHSI indicators such as the KI 208/209 products.

Additional interface options include pairing the GNC 355 with a dual-link Garmin Automatic Dependent Surveillance-Broadcast (ADS-B) solution, such as the GTX 345 or GDL 88. When paired with these products, the GNC 355 is capable of displaying subscription-free Flight Information Service-Broadcast (FIS-B) weather and ADS-B traffic targets, which includes patented TargetTrend and TerminalTraffic.

Wireless Connext devices running the Garmin Pilot and FltPlan Go applications. Pilots can also use the Flight Stream 510 to access the wireless benefits of Garmin’s Database Concierge, which uploads aviation database information from the Garmin Pilot app to the GNC 355 in minutes.

The GNC 355 provides a number of additional benefits, including graphical flight plan editing, allowing pilots to more easily edit their flight plan based on an ATC amendment or weather. Features such as FastFind simplify flight plan entry by applying predictive logic to suggest airports and waypoints using current GPS location, while Smart Airspace makes it easier to identify pertinent airspace on the moving map.

The addition of SafeTaxi airport diagrams displays runways, taxiways, Fixed Based Operators (FBOs), hangars and more relative to the aircraft’s location on the airport surface.

The GNC 355 and GNC 355A can be purchased through the Garmin Authorized Dealer network at that time starting at a list price of $6,9951 and $7,6951 respectively.

European Union Aviation Safety Agency (EASA) validation is expected at a later date.

A free GNC 355 trainer app is also available for download on Apple mobile devices, which allows customers to explore the feature set.

August 9, 2019