The European GNSS Agency (GSA), in collaboration with the Council of European Geodetic Surveyors (CLGE), has launched the Geomatics on the Move 2020 competition. The event aims to foster the use of European Union (EU) satellite programs Galileo, EGNOS and Copernicus among students, young professionals, entrepreneurs and small and mid-sized businesses to create innovative geomatics applications and solutions across all over Europe.
Building and expanding on the CLGE Student Contest, which has been held for the past nine years, the new Geomatics on the Move Prize Contest targets applications that integrate the use of additional technologies such as artificial intelligence, machine learning, augmented and virtual reality, as well as supplementary remote sensing data sources like drones, GSA said. Solutions animated through mobile phone applications or other easy-to-use platforms are also accepted.
“This is the ninth year of partnership between the Council of European Geodetic Surveyors and the GSA; over the years we have seen some exciting and innovative solutions emerge that leverage the EU Space Programme to deliver practical solutions for the mapping and surveying community,” said GSA Acting Executive Director Pascal Claudel. “This year, as we recover from this global setback, I look forward to seeing even more novel ideas — from all over the European Union — able to respond to current and future challenges.”
The competition will be organized in two stages. The first phase is an open call for ideas, during which applicants submit posters describing their ideas. The deadline for these submissions is Oct. 16.
The proposals then will be evaluated by the GSA and CLGE, and a maximum of 10 projects will be chosen to present their pitch during the finals. The selected applicants will refine their poster and prepare their pitch, for which technical support and training will be made available.
The official award of the Geomatics on the Move prize contest will take place virtually, during the European Space Week, taking place Dec. 7-11. During this event, finalists will present their solutions to the evaluation board, and winners will be announced on the official contest site.
With an overall prize of €30 000, a set of 10 prizes will be offered in two categories. The first of these categories targets EU space-based traditional geomatics solutions and the second targets integrated geomatics solutions. he first category is looking for solutions in which the main innovation is based on the use of EGNSS, employing traditional equipment such as surveying or GIS grade GNSS receivers for applications such as cadastral, marine and mining surveying or GIS mapping. The integrated geomatics category targets integrated surveying solutions that use Galileo or EGNOS and leverage cutting-edge tools and technologies such as drones, mobile mapping, laser scanners or augmented/,mixed reality, both within geomatics applications or beyond.
1976: The first military GPS five-channel receiver built in one of several programs that studied the feasibility of GPS. The receiver weighed more than 270 pounds and had seats for two operators. (Photo: Rockwell Collins/Smithsonian)
Like the internet before it, GPS started as a niche technology and became a universally recognized one, though much misunderstood and often taken for granted. Both systems originated in the U.S. Department of Defense (DOD) to support military missions, and then exploded into mass-market civilian technologies. While the internet passed from military to civilian hands very early in its history, GPS is still operated by the U.S. Air Force, making it a unique experience for the DOD: a system for which it is responsible that has orders of magnitude more civilian applications and users than military ones.
GPS has transformed entire professions — most notably, surveying; created new industries — such as ride sharing; boosted innumerable fields of scientific research — from archaeology to zoology; facilitated many aspects of everyday life — such as finding retail outlets and getting there; and given an advantage to U.S. military forces. One application discussed 30 years ago that has not yet lived up to its promised return on investment is precision agriculture.
Challenges and debates that loomed large in the early days turned out to be growing pains —most notably, Selective Availability (SA). In 1990, Javad Ashjaee reflected the attitude of much of the GPS industry and user community when he said, “I can’t think of a word to say how bad it is.” Other debates have proven more persistent — such as the interference threat posed by LightSquared, reborn after bankruptcy as Ligado Networks.
GPS first drew considerable publicity in the wake of Desert Storm, when it became the subject of television features, newspaper reports, and special sections in the pages of recreational catalogs. “Ironically,” Brad Parkinson pointed out in September 1994 in GPS World, “civil companies [such as Garmin] developed most receivers used in Desert Storm, with no help from military sponsorship.” Later that decade, while most people were finally aware of GPS technology, it began disappearing deep into its applications and the systems that use it.
In September 1991 — three and a half years before U.S. Air Force Space Command declared the system’s full operational capability (FOC) on April 27, 1995 — in a speech to the International Civil Aviation Organization in Montreal former FAA Administrator James B. Busey said: “I want to emphasize that we fully support the eventual replacement of [GPS] by other systems — and we are certain that will happen.” That may still happen, in the distant future. However, what Busey did not foresee is that GPS became but an element, though a key one, in a much larger positioning, navigation and timing (PNT) system. This worldwide system includes three other GNSS and two regional ones, several publicly and privately operated augmentation services, and a wide range of complementary and alternative technologies. These include inertial navigation (which has advanced much in the past three decades) and RF signals of opportunity. It may soon include navigation signals from non-GNSS satellites, eLoran, enhanced distance measuring equipment, and Earth-fixed navigation using very low frequency.
I began my current career in geospatial technologies exactly 20 years ago, as this magazine’s managing editor, just a few months after the end of SA increased GPS’ accuracy by an order of magnitude, and equally expanded the number of its potential applications. Yet today, I still marvel at how pervasive this technology has become and how much further it will transform our lives.
I will end with a quote from an early GPS World columnist, Hale Montgomery, who wrote in October 1991, “GPS users show an insatiable appetite for ever more precise data. Give them a mile and they want an inch.”
Seeking back issues: I have the entire collection of GPS World’s print edition, except for the first issue, the 10 issues in the second year (1991), and the September through December 1993 issues. I would be thrilled to receive those missing issues, or facsimiles, from anybody who has them. Email [email protected].
Septentrio, a provider of high-precision GNSS positioning solutions, has partnered with Digi-Key Electronics, a global electronic components distributor. Digi-Key now offers mosaic-X5 globally for customers who need secure and reliable high-accuracy positioning in a compact and low-power form factor.
Image: Septentrio
Septentrio’s mosaic-X5 features complete multi-frequency multi-constellation technology and tracks every existing and future signal from all GNSS constellations.
Such signal diversity coupled with advanced anti-jamming technology allows mosaic-X5 to deliver centimeter-level positioning with maximum availability even in challenging industrial environments. This makes mosaic-X5 an ideal positioning solution for applications such as robotics, automation, telematics and many more.
“Our mosaic-X5 is an advanced GNSS receiver module without performance compromises. With its small form factor and low-power design, mosaic-X5 brings high-performance positioning to volume applications,” said Francois Freulon, head of product management for Septentrio. “Having Digi-Key as a distributor enables us to scale and reach out to find new markets and applications where secure high-accuracy positioning is required.”
“Digi-Key is excited about the new partnership with Septentrio,” said David Stein, vice president of global supplier management for Digi-Key. “Demand for high-accuracy GNSS receivers with secure and robust positioning is growing strongly, as they continue to be implemented into new applications and devices. Digi-Key offers customers an easy path to order, develop and deploy with the latest technologies available, including Septentrio’s robust and precise GNSS devices, which have the latest anti-jamming and anti-spoofing technology.”
Our ongoing battle with COVID-19 has shown we can adapt to radical changes. A big, but worthwhile, change would be to convert our existing land databases to a cadastre system.
Any place that one may travel around the globe, they will find boundary lines that define properties and regions. For some countries, these parcels may be primarily owned by the government while in more developed nations, a large percent of the land is owned by private citizens.
These parcels, when looked at together, together create a large jigsaw puzzle that seemingly fits together perfectly. Visually, all the lines should fit snugly to their adjacent neighbor so that the sum of the parts equals the whole. This system, called a cadastre, has many redeeming qualities and makes for an efficient choice of keeping an inventory of a region or country’s parcels and infrastructure.
Origins of the cadastre system
The cadastre system of parcel registration is the database of choice for determining land ownership and taxes on property through much of the developed world. Most of the places where this system of parcel registry consists of centralized governments usually have more oversight and legislative power than more “free” countries like the United States.
Also, these countries in which these systems exist are typically small and/or have a manageable number of parcels so the development of the cadastre is much more controlled and maintained.
To help us understand the origin of this parcel system, let us explore the background of cadastre and its beginnings:
Definition: an official register of the quantity, value, and ownership of real estate used in apportioning taxes Origin: Mid-19th century from French, from cadastre ‘register of property’, from Provençal cadastro, from Italian catastro (earlier catastico), from late Greek katastikhon ‘list, register’, from kata stikhon ‘line by line’. (Source: Merriam-Webster.com)
In the years after the fall of the Roman Empire and through the end of many feudal societies, land ownership was transferred to individuals and families with the expectation of paying a tax to the government for this opportunity. Landowners could plant and harvest their own crops, raise farm animals for labor, and provide various goods and services to the community.
Besides a small fee for conveyance, the government would ask for a “meager” tax to be paid regularly. Land that was sold to these individuals was recorded in a “cadastre” for tracking of ownership and tax payment. These records were primitive in nature and relied heavily on associating a parcel number to the owner versus an actual legal description to describe the property.
It was not until more sophisticated and elaborate surveying instruments were developed that physical descriptions of the land were used to determine boundaries.
Cadastre system gives way to legal descriptions
This cadastre system of parcel management continues to exist in modern times in many parts of the world with one notable exception: The United States. Some will equate our parcel indexing system as being a traditional cadastre, but this numbering procedure is secondary to the means and methods of parcel conveyance in the U.S.
For the non-surveyor reader, in the U.S. over the past few centuries a multitude of land systems have been used to establish parcel boundaries , each with their own unique system of describing land and conveyances. These types of land transactions began after the establishment of the colonial states and rapid expansion into previously unmapped territories.
The push westward across the country introduced the Public Land Survey System (originated by Thomas Jefferson) and established sectional land divisions. As we encountered (and acquired) new territories, including the Louisiana Purchase and Texas, existing land measuring units and description methods were maintained to preserve these systems. No matter how the parcels are described, we rely heavily on the grantor/grantee system of transfer of ownership and rights throughout most of the country, with parcel numbering being applied post-transaction.
So why is the grantor/grantee system the weak link in the chain of parcel establishment and conveyance? Many times, it comes down to the legal description and how it was created. Our system allows for the creation of a parcel by varying means by the professional land surveyor. The biggest issues occur when parcels are defined by a metes and bounds description with little to no reference to adjoining property or known monuments.
When the legal descriptions of these parcels come into play, that is when the trouble starts, with calls made to attorneys and surveyors to help straighten everything out. To the common layperson who owns land or is looking to buy a parcel, it may seem unthinkable that parcels do not naturally fit seamlessly together with no gaps or overlaps. While the quality of survey data has increased in precision, the accuracy of marrying old data with the new suffers in many ways. How did we get to this point? Let us step back in the not-so-distant past to review how things have progressed throughout my short career.
Set the flux capacitor to the early 1980s…
Before computers and CAD, most agencies adopted a system of parcel and right-of-way mapping manually drafted on large sheets of durable paper or film. Depending on the municipality or county one was in, each sheet could represent either a quarter section (approximately 160 acres) or one half of a quarter section (approximately 80 acres) within a standard section of the Public Land Survey System (PLSS) established by the General Land Office (GLO) of the U.S. (now known as the Bureau of Land Management).
These maps were based upon standard measurements within the given quarter section and drawn using 90-degree corners at the edges of the sheet. The linework depicting the parcels within blocks and larger areas was drawn as close to scale as possible but was intended to be a graphic representation of the shape rather than an accurate reproduction. Considering the technology and measuring devices/capabilities of the time, these records were very helpful in performing retracement surveys of existing properties.
Because these surveys and parcel recordkeeping were performed long before computers, plotters, and CAD software became the norm, surveyors calculated and documented their work using manual computation and drafting from handwritten notes collected in the field. Not every parcel has 90-degree corners and lengths that are integers, so mapping departments for governmental agencies drafted new surveys and parcel boundaries to fit within the existing base sheets. Throw in the varying measurements from different surveyors and we have the real-life jigsaw puzzle that does not fit.
Because the aforesaid mapping departments produced parcel numbering after the creation and conveyance of the property, the damage is already done in conforming with adjacent properties. This is an important factor in the professional surveyor’s responsibility to protect the public when performing an original survey for a new parcel and/or subdivision and utmost care must be observed.
We have an army of land surveyors across the country shaping parcels to fit within a large jigsaw puzzle with an instruction sheet that must be strictly followed. One missed measurement or corner monument is in the wrong position, and we now have two or more parcels that will not fit together in the puzzle.
Many mapping professionals will point, however, to the geographical information system (GIS) and how it improved this convoluted method of parcel databases. But did it?
The digital spaghetti bowl
For a large part of the U.S. where a data-intensive GIS has been created and maintained, it is a step in the right direction, but it still lacks the overall efficiency of a cadastre. Very few GIS databases contain survey-grade parcel establishment on recognized horizontal and vertical datums. Most are parcels and roadways digitized from old mapping and records that are vague graphical representations at best.
One of the most important pieces of the GIS database are the base layers that contain control points and parcel/right-of-way lines that coincide with the datums that govern the region or state. Many governmental agencies do not employ a professional surveyor or surveying staff educated and trained to establish these datums within the database.
Incorrect GIS parcels information. (Image: Tim Burch)
Most times, the base layers are established “close enough” using aerial mapping and other data, including handheld GNSS receivers to collect infrastructure improvements. This is not a knock on these departments or individuals; they created the best possible database with the information on hand.
When merged with aerial mapping and/or survey-grade data, the graphical information from the archival records can be confusing and misleading, especially to those who are not educated to understand the data.
Is the cadastre an upgrade?
The reason to consider converting all the existing parcel mapping and subsequent infrastructure/improvement mapping to a cadastre are simple: technology. We have previously discussed cities building digital twins (“Surveying and Geospatial Data,” GPS World, July 2020) utilizing remote sensing and a multitude of GNSS-capable products.
Besides surveyors, many professions and trades use GNSS technology as a tool within their work environments. Our nation has experienced rapid growth in the last 150 years. The Industrial Revolution and the advancement of machinery, materials and building techniques have greatly impacted the ability to build more infrastructure and improvements. Many of these improvements and utilities have exceeded their useful life but have no timelines for replacement.
Developing accurate maps of this aging infrastructure will ensure a proper data set from which a replacement design can be made. Couple this ability to work in a geospatial environment with other datasets, including aerial/satellite photography and lidar acquisition, and it gives us a nearly unlimited ability to map our world in appropriate datums with greater accuracy and precision. Governmental agencies could utilize this system to monitor illegal activities (such as dumping, mining, unpermitted construction) and gauge environmental concerns (drainage issues, problematic runoff, deteriorating infrastructure) to better protect the public. This system could also be used to refine our property tax system and work towards a more equitable means of assessing our properties.
None of these potential changes and upgrades would have been possible 40-50 years ago; the invention and adaptation of GNSS have allowed these technologies to emerge. We continue to find new ways of measuring and mapping, so using these new techniques should be foremost on our minds to make these previous tedious tasks much easier to accomplish.
The hurdles to change
The biggest challenge, in my professional surveying opinion, will be adapting millions of parcels and deeds to a new database and applying them to the current datums. For instance, here is an example of potential (and recordable!) legal description:
“Beginning at the northeast corner of the parcel, said corner being the intersection of the south right-of-way line of Smith Street with the east right-of-way line of Jones Street; thence easterly on the said south line of Smith Street to the northwest corner of the Williams parcel per Deed No. 12345; thence southerly on the west line of said Williams parcel to the north right-of-way line of Main Street; thence westerly on the said north line of Main Street to the intersection with the said east right-of-way line of Jones Street; thence north on the said east right-of-way line of Jones Street to the point of beginning.”
Example of “bounds” legal description. (Image: Tim Burch)
While this is only a made-up example, it does represent a generally accepted legal description for parcel conveyance in most recording agencies. What does a mapping department do with this kind of legal description to place it accurately within a GIS or cadastre? Unless the four adjoining legal entities (Smith Street, Jones Street, Main Street, and the Williams parcel) exist geospatially within the database, the technician will have a tough time inserting this parcel into the records. Unless the entire surveying community is up to the challenge of working solely in an approved geospatial datum for all their work, much of this effort will not accomplish anything.
The other roadblock to converting our current systems to a cadastre is the rest of the parties who work with legal documents, plats, and infrastructure; they may not be up to the challenge for making a radical change for the better. From the assessor’s, recorder’s, and mapping offices to the title companies and attorneys, many have an attitude that the system is too big to revamp. Because they only work in one part of the overall system, they do not see the benefit of blowing it all up to make it a more robust and useful database.
Practically speaking…
Revamping of any system within the varying levels of government is costly, no matter what branch or region is discussed. Governmental agencies are being asked every day to do more with less and provide more value in their services with few numbers of staff.
While there may be a large upside to converting our existing databases to a cadastre, the downside is the effort and cost to do so. Yes, the new system would be scalable and easily adaptable for more infrastructure growth and could be expanded in an infinite number of ways. We can liken this proposed idea to converting all weights and measures to the Metric System: going metric will make lots of tasks and procedures easier, but flies in the face of everything we know as a society.
However, our ongoing battle with COVID-19 has shown we can adapt to radical changes. The cadastre is a better system, but I do not want another worldwide disaster to convince us to change.
Lanner Electronics Inc., a designer and manufacturer of network appliances and intelligent edge computing platforms, has launched the R3S series of rugged, EN-50155-certified fanless vehicle/rail computers.
The R3S is equipped with a u-blox NEO-M8N module, which receives GPS, Galileo, GLONASS and BeiDou with the default set for GPS + GLONASS dual band.
Powered by Intel Atom x7-E3950 processor (formerly Apollo Lake) and Intel HD graphics 505 processor, R3S series offers power-efficient performance for consolidating the in-vehicle workloads such as video surveillance, control/monitoring, passenger information, and Wi-Fi hotspot sharing.
To ensure proper operations in moving vehicles, R3S series is certified with EN50155, EN50121-3-2, EN50121-4, EN50125-3 and EN45545 standard, E13 standard and has passed MIL-STD-810G shock and vibration resistance certifications. R3S series can operate under wide operating temperature range (-40~70° C) and 24~36/72~110 voltage input, indicating its excellent reliability in harsh railway settings.
Designed for in-vehicle surveillance, the new R3S series equip with 6x M12-protected PoE ports (any 3 or 4 ports can support IEEE 802.3at PoE+) for IP camera or wireless access point connection and one external removable 2.5-inch HDD/SSD drive bay for recorded footage storage.
For edge-to-cloud connectivity, R3S uses its internal GPS/GLONASS chipsets for GPS tracking and has two M.2 slots with up to 4x SIM card readers for failover LTE connection.
For consolidating the in-vehicle workloads such as in-vehicle control/monitoring and passenger information, R3S features a variety of I/O support, including 2x HDMI, DI/DO, 3x COM/CAN BUS and 4xUSB ports.
Amazon’s latest delivery drone design was unveiled in June 2019. (Photo: Amazon)
Amazon has received U.S. Federal Aviation Administration (FAA) approval to use drones to deliver packages, which Amazon says will reduce package delivery time to as little as a half-hour.
The approval will give Amazon broad privileges to “safely and efficiently deliver packages to customers,” the FAA said.
Amazon joins UPS and Alphabet-owned Wing, which previously won FAA approval for their drone delivery operations.
The approval falls under Part 135 of FAA regulations, which regulates package delivery by drone. All part 135 participants must go through a five-phase process for certification.
“The FAA is encouraging innovation through the Unmanned Aircraft Systems (UAS) Integration Pilot Program (IPP) by working with industry, state, local, and tribal governments to realize the benefits of drones, while informing future rules and regulations,” according to the FAA.
“Participants in these programs are among the first to prove their concepts, including package delivery by drone through part 135 air carrier certification. Part 135 certification is the only path for small drones to carry the property of another for compensation beyond visual line of sight.”
Amazon said it will use the FAA’s certification to begin testing customer deliveries. The company said it went through rigorous training and submitted detailed evidence that its drone delivery operations are safe, including demonstrating the technology for FAA inspectors.
Tilt compensation to increase productivity for land surveyors
Trimble has introduced the Trimble R12i GNSS receiver, the latest addition to its GNSS portfolio. The Trimble R12i incorporates inertial measurement unit (IMU)-based tilt compensation using Trimble TIP technology, which enables points to be measured or staked out while the survey rod is tilted.
The tilt function is designed to empower land surveyors to focus on the job at hand and complete work faster and more accurately.
The IMU-based tilt compensation capability of the Trimble R12i builds on Trimble’s unrivaled ProPoint GNSS positioning engine, which delivers more than 30 percent better performance in challenging environments compared to the Trimble R10-2 receiver across a variety of factors, including time to achieve survey precision levels, position accuracy and measurement reliability.
Designed with flexible signal management that enables the use of all available GNSS constellations and signals, the Trimble ProPoint GNSS engine provides new levels of reliability and productivity.
Photo: Trimble
In addition, the ProPoint engine is a key enabler of the new TIP technology. Surveyors can continue to use the R12i’s tilt compensation functionality even in challenging environments when other solutions struggle to maintain GNSS and inertial positioning.
The Trimble TIP technology allows users to accurately mark and measure points in areas previously inaccessible for GNSS rovers such as building corners, or in hazardous situations, for example the edge of an open excavation. The receiver operates calibration-free out of the box and is resistant to magnetic interference from sources such as cars or electrical utility boxes.
The R12i also features real-time automatic inertial navigation system (INS) integrity monitoring. This system allows users to detect and correct for IMU biases introduced by use over time, temperature or physical shocks helping ensure measurement quality and integrity for the life of the receiver.
“The R12i represents Trimble’s dedication to perfecting the user experience with the industry’s best GNSS engine and now robust tilt compensation,” said Ron Bisio, senior vice president of Trimble Geospatial. “Trimble has been the leader in GNSS technology for more than 30 years and the R12i demonstrates our continued commitment to providing surveyors with the world’s most advanced and trusted GNSS systems.”
The Trimble R12i GNSS System is available now through Trimble’s Geospatial distribution channel.
Applanix, a Trimble company, has introduced the Trimble AP+ Air OEM solution for direct georeferencing of airborne sensor data.
The solution enables users to accurately and efficiently produce maps and 3D models without the use of ground control points.
The Trimble AP+ Air is a powerful solution for manned platforms, yet small enough for use on unmanned aerial vehicles (UAVs). It is also compatible with virtually any type of airborne remote sensor, including photogrammetric cameras, lidar, hyper and multispectral cameras, and synthetic aperture radar.
Comprised of next-generation compact, low-power hardware, the Trimble AP+ Air features dual embedded survey-grade GNSS chipsets, an onboard inertial measurement unit (IMU), an external IMU, and the all-new Applanix IN-Fusion+ GNSS-aided inertial firmware. It is configurable to support the direct georeferencing accuracy demands of low-flying UAVs to high-altitude manned platforms.
“We have taken the most advanced features of Applanix direct georeferencing and Trimble GNSS technology and packaged them into a powerful new, compact and versatile solution,” said Joe Hutton, Applanix’ director of inertial technology and airborne products. “It provides the flexibility required by systems integrators to embed a single hardware solution that can then be configured to meet the different direct georeferencing needs of a specific sensor type, whether flown on a UAV or manned aircraft. It truly is an ‘integrate once, use many times’ solution.”
The Trimble AP+ Air is fully supported by the Applanix POSPac MMS post-processing software, which features CenterPoint RTX post-processing for centimeter-level positioning anywhere in the world without the need for base stations. These capabilities make the solution ideal for integrators to produce a highly efficient airborne mapping system.
For lidar integrators, the Trimble AP+ Air is compatible with the POSPac MMS LiDAR QC Tools for computing boresight as well as adjusting the relative accuracy of the POSPac trajectory being used to generate the point cloud. For integration with cameras, the solution is supported by the POSPac MMS Photogrammetry Tools for computing boresight and performing camera IO quality control.
The Trimble AP+ Air OEM solution and POSPac MMS are available through Applanix sales channels.
Advancements in sensors, cameras and automation have fueled the growth of the aerial imaging industry, which is expected to reach $2.83 billion by 2022.
By Swamini Kulkarni
Unmanned aerial vehicles (UAV), or drones, often gain the spotlight with to their ability to capture the view from a vantage point. For years, airborne cameras have clicked never-seen-before pictures across planet. Now imaging technology is utilized to monitor natural calamities and borders of countries.
Drones have been quickly adopted in various industries including surveillance, geospatial mapping, post-disaster monitoring, and even entertainment. The advancements in sensors, cameras and automation have fueled growth of the aerial imaging industry.
Cameras mounted on balloons, kites and now drones are used widely across various verticals such as government, agriculture, civil engineering and research. Surveillance through satellite imagery has challenges, many of which drones can overcome. Drones can be used whenever we want and can be equipped with lidar systems, geographic information systems and advanced cameras. This has created lucrative opportunities in the aerial imaging industry.
According to Allied Market Research, the global aerial imaging market is expected to reach $2.83 billion by 2022, growing at a CAGR of 12.9% from 2016 to 2022. The launch of novel and intuitive cameras has further increased the popularity of aerial imaging.
Advent of novel, intuitive cameras for aerial imaging
AirSelfie, a prime market player in the aerial imaging industry, launched AIR PIX aerial camera at Consumer Technology Association (CES) 2020. The company announced that it has started shipping AIR PIX+ to customers the world’s smallest pocket-sized aerial camera. Moreover, it declared that it would make available AIR DUO, the aerial camera equipped with the dual parallel camera later in 2020. Both of these cameras offer state-of-the-art technology and would prove to be vital in aerial imaging and capturing videos from the air.
Skydio, the leading U.S. manufacturer of drones and autonomous flight technology, recently launched new software solutions and autonomous drone platform for situational awareness and inspection. It is observed that despite the potential drones showcase in aerial imaging, its adoption is still limited due to concerns regarding the risk of crashes of autonomous drones.
Moreover, the requirement to hire experienced pilots and data security concerns prevent firms from scaling their aerial imaging programs. That’s why Skydio aims to unlock the potential through this autonomy software and change people’s perspective toward drones.
In addition, the company has partnered with Eagleview, a leader in aerial imagery industry and data analytics to empower home insurance agents to offer accurate inspection of residential homes without the use of expert drone pilots. This technology is expected to be available in the fourth quarter of 2020.
Artificial intelligence: Future of aerial imaging
Today, every industry is searching for ways to operate devices remotely or at least with minimum physical contact. With the experience of global pandemic keeping in mind, the future is clearly bright for autonomous drones.
Several industries, including aerial imaging, rely on advancements in autonomous UAVs. Moreover, the success of aerial imaging depends on both autonomous drones and carefully dealing with the data gathered by aerial cameras. This is where artificial intelligence (AI) comes into the picture.
For use of aerial imaging for property surveillance, there is a dire need for a solution that can streamline data analysis, make sense of the data gathered by cameras, and scale up the level of details offered by aerial imaging.
AI-based aerial imaging can be used for automated property analytics and streamline facilitation of risk underwriting and claim management. Moreover, it can offer datasets to improve risk modeling. AI-powered aerial imaging technology can leverage AI to detect changes in property evaluation, which can benefit public safety and city planning.
COVID-19 increases data demand
We live during a period of drastic change. The COVID-19 pandemic has influenced almost every industry across the globe and has increased the demand for quality of data despite a lack of resources. Moreover, there is a need for faster and better data analysis to help industries scale up. The incorporation of AI and aerial imaging can benefit organizations to scale up their operations and streamline their processes at affordable costs.
Nearmap, a prominent aerial imagery company, has launched its innovative Nearmap AI for automatic aerial imagery insights at scale. This technology is the first among aerial imagery to offer AI analysis along with high-definition aerial images on a commercial scale. Moreover, it enables customers to automatically detect ground features and verify insight against aerial imagery at a larger scale.
It is clear that the use of aerial imaging will increase in the future. Moreover, the integration of AI in aerial imaging will help organizations to scale up their business and aid in data analysis to gain valuable insights.
It is safe to say that the aerial imaging technology has changed over time, but the desire of humans to see the world from a high above has been constant, which is exactly what should keep aerial imaging technology profitable in years to come.
Allied Market Research is offering a market report on aerial imaging.
Swamini Kulkarni
Swamini Kulkarni holds a bachelor’s degree from Pune University, India, and works as a content writer.
By Reza Movahedinia, Julien Hautcoeur, Gyles Panther and Ken MacLeod
Innovation Insights with Richard Langley
THE ANTENNA. This crucial component of any radio transmitting or receiving system has a history that actually predates the invention of radio itself. The first antennas were used by Princeton professor Joseph Henry (after whom the unit of inductance is named) to demonstrate the magnetization of needles by a spark generator. But it was the experiments of Heinrich Hertz in Germany in 1887 that initiated the development of radio transmitters and receivers and the antennas necessary for launching and capturing electromagnetic waves for practical purposes. It was Hertz who pioneered the use of tuned dipole and loop antennas–basic antenna structures we still use today. As communication systems evolved using different parts of the radio spectrum from very low frequencies, through medium-wave frequencies, to high frequencies (shortwave), and to very high frequencies and ultra-high frequencies, and beyond, so did their antennas.
There have been significant advances in the design of antennas over the years to improve their bandwidth, beamwidth, efficiency and other parameters. In fact, antenna development, going all the way back to the first antennas, has been one of continuous innovation.
GNSS antennas are no different. The antennas for the first civil GPS receivers were bulky affairs. Researchers at the Massachusetts Institute of Technology initially introduced the Macrometer V-1000 in 1982, and Litton Aero Service subsequently commercialized it. It used a crossed-dipole antenna element on a 1-meter square aluminum panel and weighed 18 kilograms. The Jet Propulsion Laboratory’s demonstration GPS receiver, unveiled around the same time, used a small steerable parabolic dish that had to be sequentially pointed at GPS satellites. Both of these antennas gave way to more practical designs. Also introduced in 1982 was the Texas Instruments TI 4100, also known as the Navstar Navigator. This dual-frequency receiver used a conical spiral antenna to provide the wide bandwidth needed to cover both the L1 and L2 frequencies used by GPS.
Subsequently, in the mid- to late-1980s, GPS and GLONASS antennas using microstrip patches were introduced for both single- and dual-frequency signal reception. The basic designs introduced then are still with us and are used for single- and multiple-frequency GNSS receivers. Miniature versions are used in some mass-market handheld receivers and for receivers in drone flight control systems. Patch antennas have also been used as elements in survey-grade antennas. A number of other GNSS antenna topologies have been developed including helices and planar spiral designs. Antennas designed for high-precision applications often integrate a ground-plane structure of some kind into the structure such as choke rings.
You might think after more than 30 years of GNSS technology development, that there is nothing new to be expected in GNSS antenna development. You would be wrong. In this GPS World 30th anniversary issue Innovation column, we look at the design and performance of an antenna that offers high performance even in challenging environments in a relatively small package. It is appropriate that it is unveiled in this column. After all, Webster’s Dictionary has defined innovation as “the act of innovating or effecting a change in the established order; introduction of something new.” This antenna might very well be a game changer.
Global navigation satellite systems (GNSS) have continued to evolve and have become critical infrastructure for all of society. Starting with the awesome engineering feat of the U.S. Global Positioning System and then the more recently developed constellations from other nations, we now have available refined signal structures with ever-improving positioning, navigation and timing accuracy.
Expanding use cases has led to the design of GNSS antennas optimized for many different applications. However, new antenna design commonly requires more than simple modifications to existing GPS antenna technologies. Design agility is needed to meet requirements such as wider bandwidth, sculpted radiation patterns (we frequently talk about radiation characteristics even for a receiving antenna assuming antenna reciprocity), optimized/reduced size, better efficiency, lower noise figure, or improvements in the more esoteric parameters such as axial ratio (AR) and phase-center variation (PCV). Nothing changes the widely unappreciated fact that the antenna is the most critical element in precision GNSS systems.
In this article, we report on the research and commercial development of a high-performance GNSS antenna by Tallysman, designated “VeroStar.” The VeroStar sets a new performance standard for an antenna of this type and supports reception of the full GNSS spectrum (all constellations and signals) plus L-band correction services. The antenna combines exceptional low-elevation angle satellite tracking with a very high-efficiency radiating element. Precision manufacturing provides a stable phase-center offset (PCO) and low PCV from unit to unit. The performance, compact size and light weight of the VeroStar antenna element make it a good candidate for modern rover and many other mobile GNSS applications.
DESIGN OBJECTIVES
The design of an improved, high-level GNSS antenna requires consideration of characteristics such as low-elevation angle tracking ability, minimal PCV, antenna efficiency and impedance, axial ratio and up-down ratio (UDR), antenna bandwidth, light weight, and a compact and robust form factor.
Low-Elevation Angle Tracking. Today’s professional GNSS users have widely adopted the use of precise point positioning (PPP) including satellite broadcast of the PPP correction data. PPP correction data is broadcast from geostationary satellites, which generally hover at low-elevation angles for many densely populated regions such as Europe and much of North America. The link margin of L-band signals is typically minimal, so that improved gain at these elevation angles is an important attribute. This issue is exacerbated at satellite beam edges and northern latitudes where the link margin is further challenged — a difference of just 1 dB in antenna gain or antenna noise figure can make a big difference in correction availability. A key design parameter in this respect is the antenna G/T, being the ratio, expressed in dB per kelvin, of the antenna element gain divided by the receiver system noise temperature, typically determined by the antenna noise figure. The G/T objective for this antenna was –25.5 dB/K at a 10-degree elevation angle.
The gain of most GNSS antenna elements, such as patches and crossed dipoles, rolls off rapidly as the elevation angle decreases toward the horizon. The polarization also becomes linear (rather than circularly polarized) at the lower elevation angles, due to the existence of a ground plane, necessary to increase gain in the hemisphere above the antenna. Improved gain close to the horizon also increases the ability of the receiver to track low-elevation-angle satellites with a concomitant improvement in the dilution of precision parameters (DOPs; a series of metrics related to pseudorange measurement precision).
Most of the commercially available GNSS rover antennas have a peak gain at zenith of about 3.5 dBic to 5 dBic with a roll-off at the horizon of 10–12 dB (dBic refers to the antenna gain referenced to a hypothetical isotropic circularly polarized antenna). Typically, this provides an antenna gain at the horizon, at best, of about –5 dBic, which is insufficient for optimized L-band correction usage. In some studies, different antenna types such as helical elements have been proposed to overcome this issue. However, their cylindrical shape and longer length makes them unsuitable for many rover applications. Furthermore, the helix suffers from back lobes that can make the antenna more susceptible to reception of multipath signals from below the upper hemisphere of the antenna.
In the VeroStar design, we used wide-bandwidth radiating elements (referred to here as “petals”) that surround a distributed feed network. The petal design is important to achieve superior right-hand circularly polarized (RHCP) gain at low-elevation angles.
Tight Phase-Center Variation. The phase center of an ideal antenna is a notional point in space at which all signals are received or transmitted from, independent of the frequency or elevation or azimuth angle of the signal incidence. The phase centers of real-life antennas are less tidy, and the PCV is a measure of the variation of the “zero” phase point as a function of frequency, elevation and azimuth angles. Correction data for phase-center variation is commonly encoded in a standardized antenna exchange format or Antex file, which can be applied concurrently for precision applications.
The azimuthal orientation of rover antennas is typically unknown, so that errors for specific orientations of the antenna in the horizontal plane cannot be accounted for. The PCV correction data provided in an Antex file is usually provided as a function of elevation angle and frequency, but with averaged azimuth data for each elevation angle and frequency entry (noazi corrections). Thus, corrections can be applied for each frequency and elevation angle, but errors due to the variation in the azimuthal PCV cannot be corrected in the receiver. For real-time kinematic (RTK) systems, the net system error is the root-mean-square sum of the base and rover antenna PCVs. It is usually possible to accommodate larger base-station antennas, which can commonly provide PCVs approaching +/- 1 mm (such as those from Tallysman VeraPhase or VeraChoke antennas). In this case, the accuracy of the combined system is largely determined by the PCV of the smaller rover GNSS antenna. Thus, even with correction data, azimuthal symmetry in the rover antenna is key. In the VeroStar, this was addressed by obsessive focus on symmetry for both the antenna element structure and the mechanical housing design.
Antenna Efficiency and Impedance. Antenna efficiency can be narrowly defined in terms of copper losses of the radiating elements (because copper is not a perfect conductor), but feed network losses also contribute so that the objective must be optimization of both. Physically wide radiating elements are a basic requirement for wider bandwidth, and copper is the best compromise for the radiator metal (silver is better, but expensive and with drawbacks). This is true in our new antenna, which has wide radiating copper petals.
However, the petals are parasitic resonators that are tightly coupled to a distributed feed network, which in itself is intrinsically narrowband. The resulting wide bandwidth response results from the load on the feed network provided by the excellent wideband radiation resistance of the petals.
This arrangement was chosen because the resulting impedance at the de-embedded antenna feed terminals is close to the ideal impedance needed (50 ohms), thus requiring minimal impedance matching. The near ideal match over a wide bandwidth is very important because it allowed the impedance to be transformed to ideal using a very short transmission line (less than one-quarter of a wavelength), which included an embedded infinite balun (a balun forces unbalanced lines to produce balanced operation).
Each of the orthogonal exciter axes are electrically independent and highly isolated electrically (better than –30 dB), even with the parasitic petal coupling. To achieve the desired circular polarization, the two axes are then driven independently in phase quadrature (derived from the hybrid couplers).
Thus, the inherently efficient parasitic petals combined with the absolutely minimized losses of the distributed feed network has resulted in a super-efficient antenna structure that will be difficult to improve upon.
Axial and Up-Down Ratio. AR characterizes the antenna’s ability to receive circularly polarized signals, and the UDR is the ratio of gain pattern amplitude at a positive elevation angle (α) to the maximum gain pattern amplitude at its mirror image (–α). Good AR and UDR across the full bandwidth of the antenna ensure the purity of the reception of the RHCP GNSS signals and multipath mitigation. GNSS signals reflected from the ground, buildings or metallic structures such as vehicles are delayed and their RHCP purity is degraded with a left-hand circularly polarized (LHCP) component. Because the VeroStar antenna has more gain at low-elevation angles, a very low AR and a high UDR are even more important for mitigating multipath interference. The design objective was an AR of 3 dB or better at the horizon.
A Light, Robust and Compact Design. The user community demands ever smaller antennas from antenna manufacturers, but precision rover antennas are typically required to receive signals in both the low (1160 to 1300 MHz) and high (1539 to 1610 MHz) GNSS frequency bands. An inescapable constraint limits the bandwidth of small antennas, so that full-bandwidth (all GNSS signals) rover antennas are unavoidably larger. To date, probably the smallest, high performance all-band antenna was the original Dorne & Margolin C146-XX-X (DM) antenna, which was in its time a tour-de-force.
The overall objective for our antenna was to design a small and light-weight radiating element (given the full bandwidth requirement) with a ground-plane size of around 100 millimeters, element height of 30 millimeters or lower, and a weight of 100 grams or less. Ideally, it would be possible to build a smaller version, perhaps with a degree of compromised performance. The applications envisaged for the VeroStar included housed antennas (such as for RTK rovers) and a lightweight element suitable for mobile applications such as drones or even cubesats.
ANTECEDENTS
The central goal of this project was a precision antenna with a broad beamwidth and a good AR combined with a very tight PCV. The objective was to provide for reception of signals from satellites at low-elevation angles, particularly necessary for reception of L-band correction signals, which can be expected to be incident at elevation angles of 10 degrees to 50 degrees above the horizon.
A starting point for this development was an in-depth study of the well-known DM antenna. This antenna has been used for decades in GPS reference stations (usually in choke-ring antennas). It exhibits a higher gain at low-elevation angles (about –3 dBic at the horizon) compared to other antennas on the market (typically –5 dBic or less) and fairly good phase-center stability in a compact design. The antenna structure consists of two orthogonal pairs of short dipoles above a ground plane, with the feeds at the midpoint of the dipoles, as shown in FIGURE 1(a). The antenna can be considered in terms of the ground-plane image, replacing the ground plane with the images of the dipole as shown in FIGURE 1(b). The antenna structure then takes on the form of a large uniform current circular loop similar to the Alford Loop antenna, developed at the beginning of World War II for aircraft navigation.
But the DM antenna does suffer from some drawbacks. By modern standards, the feed network is complex and lossy with costly fabrication, which affects repeatability and reliability. The AR at the zenith is marginal (up to 1.5 dB) and further degrades to 7 dB at the horizon, a factor that becomes less relevant in a choke-ring configuration where the DM element is the most commonly used. However, we took our inspiration from the DM structure and give a nod to its original developers.
The structure of the VeroStar antenna is shown in FIGURE 2(a). It consists of bowtie radiators (petals) over a circular ground plane. The petals are coupled to a distributed feed network comprised of a simple low-loss crossed dipole between the petals and the ground plane. The relationship between the petals and the associated feed system provides a current maximum at the curvature of the petals instead of at the center of the antenna as seen in FIGURE 2(b), and in this respect achieves a current distribution similar to that of the DM element.
This arrangement increases the gain at low-elevation angles, which greatly improves the link margin for low-elevation angle GNSS and L-band satellites. The circular polarization of the antenna at low-elevation angles can be significantly improved by optimizing the petal’s dimensions such as its height, width and angle with respect to the ground plane. This solves the problem of asymmetry between the electric and magnetic field planes of the antenna radiation pattern, which usually degrades the AR at low-elevation angles. Based on the studies conducted in our project, it was found that the bowtie geometry of the radiators, as well as its coupling to the feeding network, can improve both the impedance and AR bandwidth. By these means, we were able to produce a very wideband, low-loss antenna covering the entire range of GNSS frequencies from 1160 to 1610 MHz. The matching loss associated with the feed network is under 0.3 dB, and the axial ratio remains around 0.5 dB at the zenith and is typically under 3 dB at the horizon over the whole GNSS frequency range.
In the early stages of the project, we thought that just four petals would be adequate for our purpose. However, as we progressed with further experimentation and simulation, it became clear that increasing the number of petals substantially improved symmetry, but at the cost of complexity. Ultimately, we determined that eight petals provided considerably better symmetry than four petals with an acceptable compromise with respect to feed complexity.
MEASUREMENTS
The far-field characteristics of the VeroStar antennas were measured using the Satimo anechoic chamber facilities at Microwave Vision Group (MVG) in Marietta, Georgia, and at Syntronic R&D Canada in Ottawa, Ontario. Data were collected from 1160 to 1610 MHz to cover all the GNSS frequencies.
Radiation Patterns and Roll-Off. The measured radiation patterns at different GNSS frequencies are shown in FIGURE 3. The radiation patterns are normalized, showing the RHCP and LHCP gains on 60 azimuth cuts three degrees apart. The LHCP signals are significantly suppressed in the upper hemisphere at all GNSS frequencies. The difference between the RHCP gain and the LHCP gain ranges from 31 dB to 43 dB, which ensures an excellent discrimination between the signals. Furthermore, for other upper hemisphere elevation angles, the LHCP signals stay 22 dB below the maximum RHCP gain and even 28 dB from 1200 to 1580 MHz.
Figure 3 also shows that the antenna has a constant amplitude response to signals coming at a specific elevation angle regardless of the azimuth angle. This feature yields an excellent PCV, which will be discussed later.
FIGURE 3 . Normalized radiation patterns of the VeroStar antenna on 60 azimuth cuts of the GNSS frequency bands. (Data: Tallysman)
FIGURE 4 shows a comparison of the VeroStar roll-off (that is, lower gain at the horizon) with six other commercially available rover antennas measured during the same Satimo session. The VeroStar roll-off is significantly lower than the other rover antennas. The amplitude roll-off from the VeroStar boresight (zenith) to horizon is between 6.5 to 8 dB for all the frequency bands.
FIGURE 4. Comparison of the VeroStar roll-off versus six commercially available rover antennas. (Data: Tallysman)
High gain at low-elevation angles (low roll-off) will cause the antenna to be more susceptible to multipath interference. Multipath signals are mainly delayed LHCP and RHCP signals. If they arrive at high-elevation angles, there is no issue because the AR of the antenna is low at those angles — thus there will be minimal reception of the multipath signals. However, in conventional antennas, low-elevation-angle multipath degrades observations due to the poor AR performance and low UDR. At lower elevation angles, our antenna has exceptional AR performance and good UDR, which significantly reduces multipath interference. Measurements in a high multipath environment were performed with the antenna and compared to other commercial rover antennas. The measurements show that the phase noise at a 5-degree elevation angle is approximately 6 to 10 millimeters over all GNSS frequencies. The other antennas perform similarly, but have a higher roll-off. This shows that the VeroStar provides a strong signal at low-elevation angles and also has a high level of multipath mitigation performance.
Antenna Gain and Efficiency. FIGURE 5 shows the RHCP gain of our antenna at the zenith and at a 10-degree elevation angle for all GNSS frequencies. The measurements show that the antenna exhibits a gain range at the zenith from 4.1 dBic at 1160 MHz to 3.6 dBic at 1610 MHz. The antenna gain at a 10-degree elevation angle varies from –1.45 dBic to –2.2 dBic and is maximum in the frequency range used to broadcast L-band corrections (1539 to 1559 MHz). The radiation efficiency of the antenna is between 70 to 89 percent over the full bandwidth. This corresponds to an inherent (“hidden”) loss of only 0.6 to 1.5 dB, including copper loss, feedline, matching circuit and 90-degree hybrid coupler losses. This performance is a substantial improvement over other antenna elements such as spiral antennas, which exhibit an inherent efficiency loss of close to 4 dB at the lower GNSS frequencies. With the integration of wideband pre-filtering as well as a low-noise amplifier (LNA), we measured a G/T of –25 dB/K at a 10-degree elevation angle.
FIGURE 5. RCHP gain at zenith and 10-degree elevation angle. (Data: Tallysman)
Axial Ratio. The AR values of the VeroStar antenna at different elevation angles are shown in FIGURE 6. The antenna has exceptional AR performance over all GNSS frequency bands and at all elevation angles, with the value no greater than 3.5 dB. This increases the antenna’s ability to reject LHCP signals caused by reflections from nearby cars or buildings. Therefore, the susceptibility of the antenna to multipath interference is greatly reduced.
FIGURE 6 Axial ratio versus frequency of the VeroStar at different elevation angles. (Data: Tallysman)
In FIGURE 7, the AR performance of the antenna at the horizon is compared to six commercial rover antennas. The VeroStar antenna has an average AR of 2 dB at the horizon (competitive antennas are typically around 6 dB), showing its ability to track pure RHCP signals and enabling outstanding low-elevation-angle multipath mitigation.
FIGURE 7. Comparison of the VeroStar axial ratio at the horizon versus six commercially available rover antennas. (Data: Tallysman)
Phase-Center Variation. We developed Matlab code to estimate the PCV from the measured radiation pattern. FIGURE 8 shows the maximum PCV of the VeroStar antenna and six commercial rover antennas for four common GNSS frequencies. It can be seen that the antenna has a maximum total PCV of less than 2.9 millimeters for all frequency bands, which is less than the other commercially available rover antennas tested. Furthermore, the PCV of the antenna does not vary significantly with frequency. This comparison confirms the exceptional low PCV of our antenna.
FIGURE 8. Comparison of the VeroStar maximum PCV at the horizon versus six commercially available rover antennas. (Data: Tallysman)
LOW-NOISE AMPLIFIER DESIGN
The best achievable carrier-to-noise-density ratio (C/N0) for signals with marginal power flux density is limited by the efficiency of each of the antenna elements, the gain and the overall receiver noise figure. This can be quantified by the G/T parameter, which is usually dominated by the noise figure of the input LNA. In the LNA design for our antenna, the received signal is split into the lower GNSS frequencies (from 1160 to 1300 MHz) and the higher GNSS frequencies (from 1539 to 1610 MHz) in a diplexer connected directly to the antenna terminals and then pre-filtered in each band. This is where the high gain and high efficiency of the antenna element provides a starting advantage, since the unavoidable losses introduced by the diplexer and filters are offset by the higher antenna gain, and this preserves the all-important G/T ratio.
That being said, GNSS receivers must accommodate a crowded RF spectrum, and there are a number of high-level, potentially interfering signals that can saturate and desensitize GNSS receivers. These signals include, for example, mobile-phone signals, particularly Long-Term Evolution (LTE) signals in the 700-MHz band, which are a hazard because of the potential for harmonic generation in the GNSS LNA. Other potentially interfering signals include Globalstar (1610 to 1618.25 MHz), Iridium (1616 to 1626 MHz) and Inmarsat (1626 to 1660.5 MHz), which are high-power communication satellite uplink signals close in frequency to GLONASS signals. The VeroStar LNA design is a compromise between ultimate sensitivity and ultimate interference rejection.
A first defensive measure in the LNA is the addition of multi-element bandpass filters at the antenna element terminals (ahead of the LNA). These have a typical insertion loss of 1 dB because of their tight passband and steep rejection characteristics. However, the LNA noise figure is increased approximately by the additional filter-insertion loss. The second defensive measure in the design is the use of an LNA with high linearity. This is achieved without any significant increase in LNA power consumption, using LNA chips that employ negative feedback to provide well-controlled impedance and gain over a very wide bandwidth. Bear in mind that while an antenna installation might initially be determined to have no interference, subsequent introduction of new telecommunication services may change this, so interference defense is prudent even in a quiet radio-frequency environment. A potentially undesirable side effect of tight pre-filters is the possible dispersion that can result from variable group delay across the filter passband. Thus, it is important to include these criteria in the selection of suitable pre-filters. The filters in our LNA give rise to a maximum variation of less than 10 nanoseconds in group delay over both the lower GNSS frequencies (from 1160 to 1300 MHz) and the higher GNSS frequencies (from 1539 to 1610 MHz).
CONCLUSION
In this article, we have described the performance of a novel RHCP antenna optimized for modern multi-constellation and multi-frequency GNSS rover applications. We have developed a commercially viable GNSS antenna with superior electrical properties. The VeroStar antenna has high sensitivity at low elevation angles, high efficiency, very low axial ratio and high phase-center stability. The lightweight and compact antenna element is packaged in several robust housings designed and built for durability to stand the test of time, even in harsh environments.
The VeroStar antenna has sufficient bandwidth to receive all existing and currently planned GNSS signals, while providing high performance standards. Testing of the antenna has shown that the novel design (curved petals coupled to crossed driven dipoles associated with a high performance LNA) has excellent performance, especially with respect to axial ratios, cross polarization discrimination and phase-center variation. These features make the VeroStar an ideal rover antenna where low-elevation angle tracking is required, providing users with new levels of positional precision and accuracy.
ACKNOWLEDGMENTS
Tallysman Wireless would like to acknowledge the partial support received from the European Space Agency and the Canadian Space Agency.
REZA MOVAHEDINIA is a research engineer with Tallysman Wireless, Ottawa, Ontario, Canada. He has a Ph.D. degree in electrical and computer engineering from Concordia University, Montreal, Quebec, Canada.
JULIEN HAUTCOEUR is the director of GNSS product R&D at Tallysman Wireless. He received a Ph.D. degree in signal processing and telecommunications from the Institute of Electronics and Telecommunications of Université de Rennes 1, Rennes, France.
GYLES PANTHER is president and CTO of Tallysman Wireless. He holds an honors degree in applied physics from City University, London, U.K.
KEN MACLEOD is a product-line manager with Tallysman Wireless. He received a Bachelor of Science degree from the University of Toronto.
FURTHER READING
GNSS Antennas in General
“Antennas” by M. Maqsood, S. Gao and O. Montenbruck, Chapter 17 in Springer Handbook of Global Navigation Satellite Systems edited by P.J.G. Teunissen and O. Montenbruck, published by Springer International Publishing AG, Cham, Switzerland, 2017.
GPS/GNSS Antennas by B. Rama Rao, W. Kunysz, R. Fante and K. McDonald, published by Artech House, Boston and London, 2013.
“Ultrahigh-frequency Loop Antennas” by A. Alford and A.G. Kandoian in Electrical Engineering, Vol. 59, No. 12, Dec. 1940, pp. 843–848. doi: 10.1109/EE.1940.6435249.
Satellite NTS-3 above Earth. (Illustration: Lt. Jacob Lutz, AFRL Space Vehicles Directorate)
L3Harris Technologies is on track to begin building the U.S. Air Force’s first Navigation Technology Satellite-3 (NTS-3) after completing the program’s critical design review.
According to L3Harris, it will integrate the program’s experimental payload with an ESPAStar Platform, planned for launch in 2022. The system is designed to augment space-based position, navigation and timing (PNT) capabilities for warfighters.
The NTS-3 payload features a modular design, and the experiment will demonstrate capabilities that can be accomplished through a stand-alone satellite constellation or as a hosted payload.
“Collaboration with our customers has enabled us to move rapidly through important milestones to design this experimental satellite,” said Ed Zoiss, president, space and airborne systems, L3Harris. “Our goal is to deliver new signals to support rapidly evolving warfighter missions.”
The Space Enterprise Consortium selected L3Harris for the $84 million contract in 2018 as the prime system integrator to design, develop, integrate and test NTS-3. The NTS-3 will examine ways to improve the resiliency of the military’s PNT capabilities. It will also develop key technologies relevant to the GPS constellation, with the opportunity for insertion of these technologies into the GPS IIIF program, L3Harris said.
The program is a collaboration with the Air Force Research Laboratory, Space and Missile Systems Center, U.S.Space Force, and Air Force Lifecycle Management Center.
UAvionix Corporation’s aircraft AV-30-C panel display has received STC (Supplemental Type Certification) approval from the U.S. Federal Aviation Administration. The AV-30-C offers pilots an effective and affordable altitude indicator (AI) or directional gyro (DG) replacement with additional features.
AV-30-C is installable as either an AI or DG and adds a suite of in-flight information to the panel out of the box, including GPS navigational data, a probeless angle of attack indicator, baro-corrected altitude, indicated/vertical/true airspeed, non-slaved heading, bus voltage, G load and more with additional features to be announced.
AV-30-C is designed to fit into nearly any aircraft with a three and one-eighth inch round instrument slot without cutting or modifying the panel. By mounting from behind the panel, AV-30-C preserves the aircraft’s original classic look while bringing the latest that modern avionics has to offer to the panel.
The AV-30-C STC provides authorization to install in FAR Part 23 Class 1 and Class 2 aircraft (singles and twins weighing less than 6000 lbs) that are listed on the AV-30-C Approved Model List (AML), containing 635 Aircraft models including Cessna, Piper, Beechcraft, American Champion, Maule, Boeing, Swift, Mooney, Aviat and others. The full AML is available at uAvionix.com/AV-30.
AV-30-C works as a single primary instrument or by installing two units, one as an AI and another as a DG. The aircraft’s original failure-prone vacuum pump system can be removed to further benefit from a fully digital primary instrument cluster.
AV-30-C extends its functionality outside the cockpit as the companion to tailBeaconX, the latest 1090/ES ADS-B transponder with Aireon support for worldwide use and future mandated airspaces. Upon tailBeaconX TSO certification, AV-30-C can double as tailBeaconX’s control interface, allowing the pilot to set the mode and squawk easily, while maintaining AV-30’s existing feature set. tailBeaconX with AV-30-C removes the need to drill additional holes in the airframe to satisfy requirements in countries outside the U.S. and keeps installation costs to a minimum.
“uAvionix is creating avionics with fundamental engineering advantages,” said COO, Ryan Braun. “These are beautiful, no-compromise certified avionics designed to deliver an affordable total cost of ownership. The AV-30-C provides an innovative probeless angle-of-attack and non-slaved directional gyro, both designed to dramatically lower the cost of installation without compromising performance. Where other avionics seem designed to be replaced, the AV-30-C will get better with age. We’re actively developing ADS-B In, electronic flight bag, transponder, and autopilot integrations to ensure AV-30-C becomes an indispensable instrument for every panel.”
AV-30-C will support third-party autopilot systems via the APA-MINI adapter, interfacing AV-30’s heading bug with legacy autopilots. The APA-MINI autopilot adapter is expected to be released in early 2021, with more advanced autopilot integrations to follow.
