Septentrio featured its AsteRx-m UAS receiver for mapping with drones at the Association of Unmanned Vehicles International‘s Xpontential 2016 show, held May 2-5 in New Orleans.
Jan Leyssens, product manager at Septentrio, gives details on the low-power AsteRx-m UAS, which offers centimeter-level accurate geotagging of images, stabilized VTOL hovering and solid interference mitigation.
CHC has launched its new N72 GNSS series, a high-end sensor designed for GNSS applications including offshore surveys and machine control, national geodetic networks, crustal deformation monitoring and bathymetry
The N72 GNSS series is designed to offer all necessary technical features, making it one of the most complete and reliable GNSS receivers for scientific and surveying industries professionals.
“To meet the market requirements from geodetic survey and demanding applications such as CORS, on-board machine control and disaster monitoring, CHC research and development has designed one of the most feature-rich GNSS receivers available on the market. The N72 GNSS went through extensive validation and stringent quality process to achieve high performance and reliability,” said George Zhao, CEO of CHC. “This new-generation GNSS sensor reinforces our commitment to provide complete solutions to GNSS professionals.”
N72 features top level specifications:
For more than 41 years, many of us who were there in the beginning have been discussing the attributes, capabilities, enabling features and shortcomings of GPS and other space-based PNT (position, navigation and timing) systems. You have likely heard most of them; historically they go something like this:
I am sure you have heard most of these. Now, allow me to update the situation with some of the developments enabled by modern signals, new techniques, and multi-frequency, multi-GNSS (Global Navigation Satellite System) “all-in-view” receivers. All of the above bulleted statements are still true, but to a lesser extent, virtually each day. As some well-known pop musicians once sang, “It’s getting better all the time.”
The future looks bright for PNT solutions, ground and space-based. I know it all sounds like a debating society, and you may have heard some of these arguments before. My point, my premise if you will, or bottom-line-upfront in military parlance, being: the GPS (space-based) limitations of the past are gradually giving way to the improved multi-GNSS capabilities of today and the combined ground-based and space-based PNT technologies of the present and rapidly arriving future.
Unfortunately, there are many uninformed so-called PNT pundits who love to posture for the press — and who are living in the past. The future is right in front of them, or in many cases in their hands, and they cannot or will not acknowledge its existence.
Current estimates are that more than 4 billion users depend on PNT daily for position, navigation and timing, or the multitude of services each of these resources enables. More than half of that number is attributable to smartphone users, which means, at a minimum, more than 2 million PNT users have a two-way communications device incorporated into their PNT receiver/sensor.
Let’s look at current high-end smartphones as examples of commercial multi-frequency, multi-GNSS “all signals available” devices. The user has a true multi-GNSS device incorporating:
with augmentations such as
The latest high-end smartphones incorporate an inertial system, a digital compass, a rate gyro, and a pressure sensor integrated with pedometer software that keep track of position, heading and velocity when external signals are lost. Add cellular tower and network-enabled positioning and timing technology, and you have a two-way communications and PNT-based multi-GNSS sensor that, as long as it has power, is never lost.
The rubidium-based (atomic-reference system) timing signals from GPS satellite vehicles (SV) are among the most stable timing frequencies ever broadcast from space. The true accuracy of the signal in space is classified, but approaches an accuracy 10 times better than what was once thought to be adequate for our warfighters.
The best clocks in any current GNSS system are the passive hydrogen masers of Galileo. Thus a PNT set-up that adds Galileo to GPS improves in more ways than one.
Twenty-five years ago, the U.S. military kept track of GPS satellite orbit locations (known as the ephemeris of the satellite) using actual GPS measurements at the control segment tracking stations. The GPS satellite ephemeris was known to a much lesser degree of accuracy than now. At the time, that accuracy was considered good enough.
Today, the ephemeris is known much more precisely, and this can be on the order of some centimeters. This has to do with not only the location of the satellite’s center of mass (c.o.m.), but the actual location from which the signal is broadcast. The position of the satellite’s broadcast antenna is known reasonably well most of the time, by very high-end users, after correcting for the arm lever between the c.o.m. and the antenna phase center. The c.o.m. itself can vary by some centimeters over time because of depletion of onboard expendables, but here we are getting into very high-order minutiae.
Suffice it to say that certain multi-GNSS scientific high-precision receivers today are used to measure tectonic movements on the order of centimeters over the course of a full year.
Just recently, with the addition of certain QZSS signals (the Japanese Quasi-Zenith Satellite System) along with the Indian (GAGAN) and Russian (SDCM) equivalents of WAAS and EGNOS, the number of multi-GNSS PNT signals available to a truly international multi-GNSS receiver exceeds 200. For example, one set of global commercial receivers routinely receive and process more than 190 PNT signals in a six-hour period. The receivers are both static and dynamic, and they are networked. The static receivers know their actual location to within millimeters, and use this location as a truth set from which all other signal data is compared.
For our example (and all parameters are software-defined and user-programmable), the location parameter may be set at 10 centimeters, meaning that any position derived from PNT signals or augmentations that differ by more than 10 centimeters from the “truth set” are immediately rejected, and that data is broadcast on the systems network, which keeps the dynamic receivers in sync as well.
The individual receivers each contribute to their own and a networked website with metadata usable by Kalman filters to which other users may choose to subscribe. This makes the multi-GNSS receivers not only receivers, but system and PNT monitors and sensors that can detect jamming, interference and spoofing attempts, which are reported.
This monitoring and tracking system is constantly evolving and incorporating new technologies while becoming more secure everyday. This is not a totally new concept, as the core system is a mature enterprise system that has been in operation and commercially viable for more than seven years.
This should be comforting information for those of you who stay up at night worrying about the safety of autonomous vehicles on land, sea and in the air.
Don’t let me give you the impression that GPS is just waiting around for other GNSS to come to its aid. GPS is aggressively modernizing itself. In Air Force parlance, “GPS III space vehicles will introduce new capabilities to meet higher demands of both military and civilian users.” As stated by GPS III contractor Lockheed Martin, the modernized system will:
• Deliver signals three times more accurate than current GPS spacecraft.
• Provide military users up to eight times improved anti-jamming capabilities.
The bottom line is that a greatly increased number of space-based PNT platforms — along with quantum improvements in computing power, cheap non-volatile memory and software-defined capabilities — have produced a multi-GNSS PNT capability that increases availability via sheer numbers, with more security and reliability on the way.
We are rapidly developing a PNT system that goes far in countering the naysayers. It takes advantage of augmentations and complimentary systems such as newer versions of Loran, (Long-Range Navigation System) and local PNT implementations such as Locata, just to name a couple of examples.
These ground-based systems are critical to the future of PNT, and have very strong signals. For instance, eLoran is extremely difficult to jam, if not actually unjammable. If a monstrous sunspot were to temporarily knock out the majority of space-based systems, the ground-based systems would more than likely still be available, if — big if here — they are fully developed. At the moment, this is not a sure thing. It is a work in progress.
Ground-based augmentations and complimentary/backup systems can in the future add a level of security for GPS and other space-based PNT systems: Why bother trying to knock out these space-based systems when there is a suitable and readily available ground-based system as a backup?
The U.S. government maintains a number of monitor stations around the globe. However, it has not historically taken advantage of the incredible capabilities of multi-GNSS receivers and sensor technology. Although NASA and other U.S. non-military agencies have been involved with multi-GNSS — specifically the Russian GLONASS — for the past 20 years or so, the use has not been widespread. Fortunately, recent changes now permit multi-GNSS receivers for government users, including the military, in certain non-targeting activities, and the government would do well to take advantage of the changes. The good news is that the majority of the capability is in the receiver design, a capability on which the current director of the GPS Directorate at the Space and Missile Systems Center (SMC) “made his bones.”
To all those critics who take every opportunity to denigrate space-based PNT, both inside and outside the government, I say: Pay attention to multi-GNSS. Stop your diatribes, because the future is arriving. Secure space-based PNT systems are here to stay.
They continue to improve and become more secure as they incorporate space- and ground-based augmentations, new PNT technologies, software-defined capabilities, multi-GNSS signals, and enhanced computing. “It’s getting better all the time.”
Allow me to repeat myself all over again. Space-based PNT is here to stay.
Until next time, happy navigating, and remember: GPS is brought to you free of charge by the United States Air Force.
Penton’s TU-Automotive has unveiled the agenda and speaker line-up for TU-Automotive Detroit 2016, which is being held June 8-9 in Novi, Michigan. The 16th annual conference and exhibition is dedicated to innovation in automotive technology, covering connected cars, autonomy and mobility.
At TU-Automotive Detroit 2016, the city’s automakers — Ford, General Motors and Fiat Chrysler Automobiles — will join international OEMs to discuss their vision for how the car can become the leading “node” of the Internet of Things (IoT), Penton says in a news release.
The 80-plus session agenda and more than 150 speakers will focus on automotive’s leading role within the rapidly expanding connected world, collaboration of efforts, resources and competencies is needed within companies and across the industry.
“Last year we saw the emergence of three core trends in automotive: connectivity, mobility and autonomy,” Gareth Ragg, managing director of TU-Automotive, says in the news release. “This year, these are coming together to form one pillar in automotive strategy, connecting with the wider connected world.”
3,000 are expected to attend this year’s event, which will cover connectivity, ADAS, mobility models, insurance, data, infotainment and more.
Keynote speakers from Ford, GM, Zipcar, Nissan, NHTSA, Jaguar Land Rover, car2go, FCA, Hyundai, MIT, Audi and Mercedes-Benz will demonstrate how collaboration will make auto the pioneer of the IoT.
Recent progress with Dedicated Short Range Communications (DSRC) Notice of Proposed Rule Making (NPRM) brings connected cars or V2X — connectivity between vehicles, infrastructure and all road users — closer to reality than ever before. If all goes well, an NHTSA mandate on DSRC in new light vehicles is expected to start around 2020 as a phase-in plan, with completion around 2025.
Regulations for aftermarket devices are expected to come soon after. The mandate is expected to leave auto OEMs to choose the applications and human-machine interface (HMI). This will be the culmination of more than a decade of technology development and standardization by U.S. Department of Transportation (USDOT), automotive OEMs and other industry partners.
Significance of V2X. According to USDOT, V2X technology can positively impact more than 80% of non-impaired vehicle crash types that result in over 30,000 deaths in the U.S. alone. A report by the Federal Highway Administration to Congress states that V2X technology is ready to be deployed in the near future and is expected to yield significant safety and efficiency benefits.
From a consumer’s perspective, V2X will be a part of a vehicle ADAS (Active Safety Driver Assistance System). Initial systems will provide information only, and these systems are expected to evolve into warning and control capabilities. In a future vehicle, information from multiple sensors including V2X will be combined/fused to generate a view of the surrounding environment. Figure 1 gives an example of such sensors including long- and short-range radar, lidar, cameras and V2X. V2X offers unique advantages over other sensors that depend on direct line-of-sight. Information can be received from vehicles not visible to other sensors, giving a much larger field of view. V2X can transmit information directly from traffic control devices, instead of inferring information from camera observations.
Figure 2 depicts the sensor fusion screen from an ADAS development platform by Renesas Electronics America. Such a platform offers the flexibility to implement an ADAS using all available sensors, for example blind-spot warning from radar, forward collision warnings from combined radar, camera and V2X, surround object detection from combined radar, lidar, vision and V2X, with information presented via an OEM-specific HMI.
V2X is built on the assumption that vehicles, infrastructure elements, and other road users are location-aware and can communicate critical information to others around them. As seen in Figure 3, the system will position all communicating V2X entities with respect to the host vehicle and security interface, which validates all relevant DSRC messages. A control area network (CAN) or a similar interface will be needed for direct access to vehicle information such as brake and turn-light status and odometer. Interfaces to long-range connectivity such as cellular networks and other data sources such as maps may also be included. The system will connect to an HMI to display information, and future systems will likely evolve to vehicle control functions.
Looking at the components of an over-the-air (OTA) V2X basic safety message (BSM), this includes a UTC-based time marker, WGS84-based position, and an estimated position error — all critical data that primarily depend on GNSS. RTCM-formatted data may also be sent as optional attachments. A BSM-like personal safety message (PSM) is also defined for pedestrians with V2X-enabled devices.
As per current Minimum Performance Requirements (MPR), a UTC time source with better than 1 millisecond accuracy is required in a V2X device. While almost all current prototypes use GNSS as source of time, others, such as NTP, may also be used. Accurate time reference is a critical prerequisite for basic DSRC functionality. MPR requires time-marked position estimates with 2D and elevation accuracy of 1.5 and 3 meters or better (1 sigma) under open-sky conditions. The automotive industry has opted to define open sky as unobstructed sky view above 5-degree elevation with seven or more satellites visible with HDOP and VDOP limits. The industry expectation is to use this criteria to select GNSS devices that could eventually support lane-level applications (better than 1.5-meter accuracy).
MPR does not put any requirements on the accuracy of the position error estimate in the BSM. It does require that a vehicle stop transmitting BSM whenever the aforementioned time and position accuracy requirements are not met. This implies that a V2X-enabled vehicle may disappear from the V2X view of others in a dense urban canyon or similar environments, leaving at least two questions for system designers from a GNSS perspective alone. First, how to reliably declare that the system cannot meet time and position accuracy requirements, and second, how to deal with the vehicle itself and other V2X entities that may cease to function or broadcast due to GNSS or other limitations. V2X systems are assumed to include inertial and vehicle sensor integration.
Road Ahead. Starting in 2017, connected vehicle pilots (CVP) in New York, Tampa, Florida, and Wyoming will be the next major milestone for V2X. These deployments will be limited to commercial fleets (taxis, public transit, city/road crews and delivery trucks) and some limited road-user categories.
Among the automotive OEMs, Toyota was the first to offer V2X-based driver-assistance technology as ITS Connect in Japan in 2015. General Motors is the first to announce a V2X technology offering in a passenger vehicle in the U.S. with an initial rollout in select 2017 models. The first phase of V2X deployments will only provide driver assistance information while subsequent iterations are expected to bring in safety-focused functions leading to control capabilities.
There is a growing interest in the cellular industry to support V2X-like communication in an upcoming release of the 3GPP standards commonly referenced as 5G. This would enable low latency, peer-to-peer communication with the advantage of an existing device provisioning/authentication infrastructure, something that needs to be built up for DSRC. However, 5G is still a concept, and judging by the lifecycle of LTE, a 5G deployment will take several years to start and several more years to fully deploy while still leaving some rural areas with legacy technology. A framework to manage commercial traffic vs. likely free safety traffic will also be required. These raise the question as to how 5G alone can support vehicle safety applications nationwide.
The FCC has recently proposed a rule to potentially open up the DSRC band for unlicensed Wi-Fi devices, provided Wi-Fi users do not interfere with the primary safety use. Automotive and wireless industry and other stakeholders are investigating the feasibility of possible co-existence in the future. Among the proposed solutions are the rechannelization of DSRC to use a smaller bandwidth and a mechanism for Wi-Fi devices to Detect-and-Vacate the DSRC band when a safety user is detected.
From a technology point of view, V2X has reached a significant milestone with R&D in various technology areas converging and critical standards being adopted recently. With Toyota V2X offering in Japan and GM V2X commitment in the U.S., customers will have V2X as an option this year, further proof that V2X will be on the roads soon. However, significant further work is needed to address the GNSS accuracy and reliability needed for next-generation systems and to address GNSS-specific vulnerabilities such as jamming or spoofing. The New York CVP, which includes deep urban canyons, will probably be a great opportunity for GNSS and V2X communicates to work together on some of these limitations.
Headquarters for the National Bank of Kuwait, a new 300-meter-tall building under construction, combines concrete, steel, glazing and glass-reinforced concrete in a unique shellfish shape. The engineering challenges behind this building led the engineers of Ahmadiah Company, the contractor, to use GNSS technology to install the core wall structure with millimeter accuracy.
They adopted the core wall control survey method developed by Joël van Cranenbroeck during construction projects in Dubai. To guarantee the precise vertical thrust of a tower during construction, complete control must be maintained of the position of each new element erected on top of the existing core walls. Such new elements, and their formwork structures, must be precisely positioned with respect to the main axis of the design reference frame, defined as the vertical positioned in the tower center. This means that the position of the formwork structures at the top of the tower must be continuously measured during erection of the building.
Core walls are constructed bit by bit, one on top of the other. Each core wall element consists of several concrete pours. The placement of the formwork structure on top of existing core walls must be done precisely, determined from the position of previously placed elements. For this purpose, control points (nails in this instance) are set in the top of the concrete. The basic task of the surveyor is to determine the coordinates of these control points and to compute and stake out the position of the formwork structure in a design reference system based on the main axis of the tower. Dual-axis inclinometers, precise leveling observations and vertical laser plummets complete the method, which is based on a sensor fusion approach.
A small network of three to four GNSS receivers and antennas are installed on top of the formwork to provide control points to total station operators. As the construction stages rise, surveyor sightings of ground-based control points decrease.
An active GNSS control point consists of a 360° reflector with a GNSS antenna screwed on its top. The coordinates obtained by post-processing the GNSS observations are transformed in the local datum and are available for any total-station “free station” calculation operating on the building top.
The technique has proven to be successful in several other projects worldwide. Comparisons with resection on ground control points, when made possible by tower height, indicated differences of less than a few millimeters.
As GNSS can only deliver such performances in differential mode, this requires setup of a local GNSS base station.
The local GNSS CORS station receiver and a geodetic-grade GNSS antenna were placed near the construction site and connected to an Internet router to provide easy access whenever the data had to be downloaded for post-processing the GNSS receivers placed on top of the building.
To confirm that the GNSS observations by the selected reference receiver match with those of GNSS receivers used in previous similar projects, a zero baseline test was performed by connecting both sets of equipment to the same GNSS antenna. Simultaneously, a temporary GNSS base station was set up using another geodetic receiver.
All the RINEX data collected over an hour was processed using open-source RTK-LIB software. The results showed less than a millimeter variation between the receiver selected for the project and those used on previous projects.
The baseline components between the temporary base station and both receivers showed respectively 1 millimeter in X and Y (WGS-84) and 2 millimeters in Z difference.
Up to 11 BeiDou satellites are now visible in the sky over Kuwait. By setting up the selected BeiDou-capable receiver as a local CORS station — processing signals over the three constellation frequencies (B1, B2 and B3) — project operators benefit from additional GNSS signals that aid positioning where obstructions make GNSS use challenging.
The National Bank of Kuwait construction is the first GNSS CORS station tracking Beidou satellite signals deployed in the Middle East area. Surveyors on this job can access remotely via the on-board web server all the information (satellites in view, quality indicators, memory, RINEX files and so on), and can evaluate the impact of new signals and new frequencies within the context of an exceptional architectural project.
The GNSS M300 Pro from ComNav Technology (Shanghai, China), a multi-purpose GNSS receiver for a range of applications, has 256 channels tracking GPS, GLONASS and BeiDou, with Galileo capability.
Joël Van Cranenbroeck established Creative Geosensing Belgium as an engineering geodesy consultancy company specialized in high-definition positioning, positioning infrastructures (CORS network) and monitoring.
Ready for Galileo
The compact FlexPak6 receiver houses NovAtel’s OEM628 triple-frequency plus L-band GNSS receiver board. It tracks all current and future GNSS constellations, with a highly configurable interface designed to meet current and future positioning and integration needs. The FlexPak6 is a GPS and GLONASS receiver that is also Galileo and Compass ready. Upgradable receiver firmware ensures easy updating to future signals. While multi-constellation tracking provides higher solution availability and reliability, its flexible communication interface broadens deployment options. It provides 100-Hz measurements for high dynamic applications. Signals tracked include L1, L2 and L2C and L5. It also has RT-2, ALIGN, GLIDE, RAIM firmware options.
NovAtel, www.novatel.com
Single- or dual-antenna receiver with latest algorithms
The AsteRx-U receiver incorporates the latest GNSS tracking and positioning algorithms, such as LOCK+ technology to maintain tracking during heavy vibration machine use and IONO+ technology to assure accuracy in regions of elevated ionospheric activity. Interference mitigation counteracts ambient and deliberate RF interference. The AsteRX-U is built around Septentrio’s latest application-specific integrated circuit (ASIC), the GReCo4, and incorporates built-in jamming detection and countermeasures, multipath rejection and fast acquisition. More than 500 hardware channels track all available constellations (GPS, GLONASS, Galileo, Beidou, IRNSS and QZSS).
Septentrio, www.septentrio.com
For applications requiring both RTK and orientation
The Trimble BD935-INS delivers GNSS and inertial technology in an easy-to-integrate form factor for demanding conditions and applications such as lightweight robotic or unmanned vehicles. It features precision GNSS with an integrated 3D micro-electro-mechanical systems (MEMS) inertial sensor package, triple frequency for both GPS and GLONASS constellation, and dual frequency for BeiDou and Galileo. The compact module augments real-time precise positioning with 3D orientation. Connectivity and configuration allow system integrators and OEMs to add GNSS and attitude to specialized or custom hardware solutions. By integrating inertial sensors onto the GNSS module, users receive more robust performance in challenging environments. The module delivers fast and reliable real-time kinematic (RTK) initialization for 1–2 centimeter positioning. The integrated GNSS-inertial engine delivers high-accuracy GNSS and DGNSS positions in challenging environments such as urban canyons, tunnels and heavy canopy.
Trimble, www.trimble.com
Capacity for galileo and other future signals
With its robust 555-channel engine, the new Leica Viva GS16 receiver is empowered by RTKplus to access all known and current signals while intelligently distinguishing which ones are the optimal combination to lock onto for accurate positioning adapting to any environmental conditions. There is also capacity for future signals, such as the full deployment of BeiDou and the expected progress of Galileo and QZSS. Thanks to SmartLink, the precise point-positioning technology, uninterrupted positioning continues even when local corrections services are unavailable due to obstructions or lack of cellular coverage. When no reference data is available, SmartLink continues to enable fully remote work. On a field tablet or controller, users can interact with immersive 3D models directly in the field, ensuring all data is collected and linked to the office.
Leica Geosystems, leica-geosystems.com
Laser scanner rolls on a trolley
SurphSLAM combines the new Surphaser 10 laser scanner and GeoSLAM’s new RealTime SLAM registration software. SurphSLAM can be used for extremely accurate high-resolution 3D mobile mapping without the need for GPS. The integration of technologies allows for the resulting point cloud to be registered and displayed in real time, facilitating the performance and speed of the survey. Surphaser scanners produce high-accuracy data sets with ultra-low noise levels. The combination of speed, low range noise, sub-millimeter accuracy and reduced size of the scanner make it suitable for a versatile mobile mapping system such as SurphSLAM. The custom-designed trolley is lightweight and collapsible.
Basis Software, www.surphaser.com; GeoSLAM, geoslam.com
OGC GeoPackage enables platform-independent data exchange
TerraGo Edge 3.9.3 features full support for OGC GeoPackage, a universal format for sharing maps and geographic data across mobile devices and platforms. TerraGo Edge enables users to import and export OGC GeoPackage as a SQLite database optimized for performance on iOS and Android devices. Release 3.9.3 closes the loop for a complete GeoPackage collaboration workflow by allowing Edge app users to import GeoPackage data from a mobile device, collect location-tagged field data, and roundtrip the information back to the GIS or other enterprise systems of record.
TerraGo, www.terragotech.com
Open-source client extended with full galileo support
Version 2.12 of the BKG NTRIP Client (BNC) real-time software for Windows, Linux and Mac now comes with complete command line interface and considerable post-processing functionality. RINEX Version 3 file editing and quality check with full support of Galileo, BeiDou and SBAS — besides GPS and GLONASS — are also among the new features. BNC version 2.12 allows simultaneous multi-station precise point positioning (PPP) for real-time displacement monitoring of entire reference station networks. Comparison of satellite orbit/clock files in SP3 format is another new feature, along with a large set of examples for various applications. BNC software was originally developed bythe Federal Agency for Cartography and Geodesy (BKG) and Czech Technical University.
BKG GNSS Data Center, https://igs.bkg.bund.de/ntrip/download
For deformation monitoring
The Leica GMX910 smart antenna is desgined for static, long-term projects requiring a high number of sensors. It can enable dynamic monitoring with up to 10-Hz data streaming and advanced multi-frequency, multi-constellation tracking. Starting with the basic GPS single-frequency receiver and adding multiple upgradable options, the antenna adapts to a wide range of GNSS monitoring applications, from complex manmade to natural structures. The smallest movements of bridges, dams or high-rise buildings are detected in real-time. The antenna supports multiple GNSS satellite systems and signals, tracking up to 555 channels. An IP67 rating against dust and water, extended temperature ranges and low power consumption enables installation of the device in remote areas and severe conditions.
Leica Geosystems, leica-geosystems.com
For disaster monitoring, traffic patrol, security monitoring
The 25-gram HX-CH6601A GNSS helix antenna for UAV and geospatial applications receives GPS L1/L2, GLONASS L1/L2 and BeiDou B1/B2. It offers exceptional pattern control, polarization purity and high efficiency in a compact form factor. The antenna is equipped with a high-quality, durable IP65 sealed radome housing and terminated with a subminiature version A (SMA) connector, which has high gain and wide beam width to ensure the signal-receiving performance of satellites at a low-elevation angle.
Harxon, www.harxon.com
1.5 gram micro ADS-B receiver
The pingRX ADS-B (automatic dependent surveillance – broadcast) receiver requires 1/100th the power of conventional ADS-B receivers. It implements sense-and-avoid capabilities for small drones operating in the National Airspace. pingRX measures 32 x 15 x 3 millimeters, which is a fraction of the size of earlier units. It receives ADS-B information broadcast by other aircraft on two frequencies approved by the U.S. Federal Aviation Administration (978 MHz and 1090 MHz.) This allows the unit to detect commercial aircraft threats within a 100-statute-mile radius in real time.
uAvioniX, www.uavionix.com
Available as turn-key sUAS or as standalone gimbal
The U1 is a professional-grade unmanned aerial vehicle for the industrial survey and surveillance markets, as well as for cinematographers. Features include redundant flight control and battery systems, customized downlink with two high-definition (HD) video feeds, stability even at full zoom with a gyro-stabilized gimbal system, and remote camera control.
Shotover, www.shotover.com
Car & Driver branded dash cam includes built-in GPS
The dash camera CDC-601 is equipped with built-in GPS and motion detection. Media shortcut keys allow the driver to manage settings and view their recordings. The camera automatically records when the driver starts the engine and shuts down when the ignition turns off. The 1080p high-definition camera has a 120-degree wide-angle lens, loop recording, time stamp and accident detection. An 8-GB card is included, but it can support up to a 32-GB card.
Summit CE Group, summitcegroup.com
Tiny inertial navigation system helps propel ROVs
The Rovins Nano is a new inertial navigation system for the offshore industry. Based on iXBlue’s fiber-optic gyroscope technology, the Rovins Nano is designed for for remotely operated underwater vehicle (ROV) pilots performing maintenance and construction operations. It offers the stability and accuracy of the inertial position, outputting true north, roll, pitch and rotation rates. It can directly transmit the ROV’s position with extreme accuracy because of its integrated INS algorithm capable of collecting acoustic data, regardless of the depth. Rovins Nano adapts itself to the user with easy configuration, installation and use. The goal is for the pilot to forget the existence of the product when maneuvering. Because of its compactness, lightness and open architecture with all third-party sensors, Rovins Nano is easy to integrate into existing ROVs.
iXBlue, www.ixblue.com
New platform optimzed for transportation departments modernizing aging CORS installations
A new PolaRx5 Continuously Operating Reference Station (CORS) platform has been optimized for state departments of transportation (DOTs) and other real-time-kinematic (RTK) network operators. The PolaRx5 is powered by Septentrio’s AsteRx4 next-generation multi-frequency engine. It offers 544 hardware channels and supports all major satellite signals including GPS, GLONASS, Galileo and BeiDou, as well as regional satellite systems such as QZSS and IRNSS. Septentrio’s Advanced Interference Mitigation (AIM+) technology enables the PolaRx5 to filter out both intentional and unintentional sources of radio interference, from narrowband signals over high-powered pulsed signals to chirp jammers and Iridium transmitters. In addition, Septentrio’s patented APME+ multipath mitigation technology guarantees superior measurement quality by eliminating short-delay multipath errors without introduction of bias. The PolaRx5 leverages Septentrio’s web interface and built-in Wi-Fi and Bluetooth interfaces to give users complete control and visibility of the receiver. The user interface integrates into existing network management systems. The web browser provides secure access to all receiver settings and status, data storage and firmware upgrades as well as a built-in spectrum analyzer for system monitoring.
Septentrio Americas, septentrio.com
Classic form for high-tech tracking
The Omata One speedometer displays essential information to cyclists in a classic form. The GPS computer inside the speedometer records with high precision so that cyclists can download their activity data to their preferred training applications or websites. On the outside, Omata One has a legible and mechanical analog movement that shows riders the speed, distance, ascent and time. The product displays only these four core pieces of information so the cyclist can focus on the ride. Omata plans to offer additional GPS speedometers for other sports.
Omata, omata.com
Adds LTE, Wi-Fi and cloud-based diagnostics to older cars
Samsung Connect Auto plugs directly into a car’s OBD II port underneath the steering wheel. It uses real-time alerts to help users improve their driving behavior, including increased fuel efficiency, while offering a Wi-Fi connection for passengers. The connection is kept secure using Samsung KNOX , the company’s mobile security platform. The backbone of Samsung Connect Auto is KNOX security and Tizen OS for interoperability. Developers can leverage Tizen and Samsung’s software development kit (SDK) to further evolve additional services. Samsung also encourages safe driving behavior by using geofencing and driver rating algorithms. In the event of an accident, emergency alerts notify the driver’s contacts, and accident concierge services are provided. A “Find My Car” app also helps in locating a car in real time using LTE and GPS. Samsung Connect Auto will initially be available in the second quarter in the U.S., with AT&T the first wireless provider.
Samsung, www.samsung.com
Context-dependent scan matching for aided navigation
By Jyh-Ching Juang, Shang-Lin Yu and Shun-Hung Chen
Context-dependent scan matching for aided navigation — finding the rotation and translation that best align two consecutive scans — provides laser-ranging data that can be blended into a GNSS navigation system. A quality index based on analysis of intra-frame point clouds assesses the scan context, accounting for variations in feature richness, to yield a robust aided navigation solution.
For robust and autonomous navigation, many different sensors have been incorporated and, indeed, fused to form a navigation suite that typically includes a GNSS receiver, inertial measurement unit, vision sensor, laser rangefinder, odometer and others. Recently, driven by the goal to achieve autonomous driving, laser range data and image data have been widely adopted in the establishment of vehicle safety and autonomy functions. Laser range data can facilitate navigation and guidance. Through the use of scan matching, vehicle motion can be detected and used in dead reckoning. The surroundings of a vehicle can also be built based on point clouds, so that a feasible path can be generated for obstacle avoidance and vehicle guidance. To some extent, the image data can also be exploited in a similar manner. The use of a visual odometry technique attempts to estimate the relative motion between two consecutive images for dead-reckoning navigation.
This article addresses a limitation in scan matching for vehicular navigation and proposes a context-dependent scheme to account for the variation of the richness of features in scan-matching-based navigation. Environmental context in terms of the richness of features is known to affect the quality of the resulting navigation performance. Thus, in scan matching, we seek to establish a quality index to quantify the quality of the resulting estimates on rotation and translation. In this manner, after fusion with other sensors, a robust positioning solution can be obtained.
Here, we briefly review the scan-matching technique and discuss the aforementioned limitation using a real-world example. We then investigate a context-dependent weighting concept, and the entropy of a scan is used to quantify the richness of its features. We find that a scan with low entropy may be prone to improper registration and an erroneous navigation result. Thus, a weighting is assigned to the scan-matching result for integrated navigation processing. To verify and demonstrate the proposed context-dependent weighting approach, the method is implemented and tested in a vehicle. The result verifies that the proposed scheme can indeed avoid improper registration and lead to robust navigation performance.
Scan matching is an enabling technique in vehicle navigation, map building and obstacle avoidance, produced by laser ranging devices. Scan matching finds the rotation and translation that best align two consecutive scans. Given two point sets {pn, n = 1,2,K,N} and {qm, m = 1,2,K,M} at two consecutive instants, the scan-matching problem is to determine a correspondence n → m(n) for the registration of two scans and a rotation matrix R and translation (shift) vector s such that the objective function is minimized:
(1)
Once the mapping m(n) is determined, the optimization of (1) can be solved analytically. The determination of the mapping from n to m(n) is typically accomplished by using an iterative method. This class of methods is termed as iterative closest point (ICP), in which the mapping m(n) is determined by searching for the closest point in the target point cloud. There have been many different variations to the ICP by using a different objective function for minimization, a point-to-plane matching, the removal of boundary and/or low-quality correspondences, and so forth. By repeating the scan-matching process, the rotation matrices and translation vectors can be determined and used in the dead-reckoning navigation process to estimate the position and attitude of the vehicle. In robotics and autonomous vehicles, the scan matching is typically integrated with the map-building process for simultaneous localization and mapping (SLAM).
Figure 1 depicts a representative result when the scan-matching technique is used in the SLAM. In the figure, the vehicle moves from the bottom to the top. As the vehicle moves, the laser rangefinder collects measurements for the determination of the vehicle and the mapping of the environment. The location of the vehicle can be estimated (in green) and the environment can be mapped (in blue) by using the scan-matching and filtering techniques. However, as also depicted in the figure, as the vehicle moves to the end of the corridor the point clouds that are obtained from the laser rangefinder (in red) are constrained, and the change of the pose of the vehicle cannot be accurately determined.
Figure 2 shows the original scans at two consecutive instants (in blue and gray, respectively) and the matched scan after the scan-matching process (in red) when the vehicle moves along the corridor.
At this point, the laser rangefinder obtains measurements that are rich in context. The rotation and translation of the vehicle can be estimated with an acceptable level of accuracy, and the vehicle can be located. In this example, the translation vector is found to be s = [11.07 0.50 –0.58]T mm and the minimal error of the objective function is 3.47. When the vehicle moves to the end of the corridor, the scans at two consecutive instants, together with the matched scan, are depicted in Figure 3.
In this case, only the end wall is observed by the laser scanner, and the determination of the rotation and translation based on scan matching is subject to errors due to the lack of features. Indeed, by applying the scan-matching technique, the translation vector is found to be s = [9.18 –2.84 13.22]T , which is obviously incorrect in the z axis component. Also, the minimal error of the objective function is 3.20, which is smaller than the error in Figure 2. Thus, the error may not provide a fair assessment of the scan matching due primarily to the fact that the error in registration is not taken into account in the objective function (1). In short, lack of features in the environment may induce improper registration and lead to navigation error.
To account for the aforementioned limitation, several methods can be adopted. One can resort to some variations of the scan-matching techniques by, for example, using feature extraction and matching. Blending with other sensors can be employed. In this case, the vehicle can be equipped with gyros to give information on the change of attitude so that the change of translation can be better estimated. This research project addressed this issue by using a context-dependent weighting to quantify the scan-matching results.
Scan matching attempts to investigate the relationship between two consecutive scans to explore the inter-frame characteristics. However, as discussed, the quality of the scan-matching result depends on the richness of features in the scan, which is revealed by examining the intra-frame characteristic. Given a scan in 2D or 3D, some quality indices can be established to assess its characteristic. For example, principal component analysis (PCA) is a widely applied technique to quantify a scan and to obtain normal vector in a polygon environment. For vehicle navigation in an outdoor environment, the PCA approach may be limited. Here, we propose the use of entropy to assess the complexity of the environment of a scan (or image).
Given a set of K random variables, the entropy is defined as
,(2)
where pk stands for the probability of the k-th random variable. The entropy is a measure that can be used to probe the randomness of a set of random variables. As each probability is bounded by 1, the entropy in (2) ranges between 0 and log2 K.
To assess the entropy of a scan, which is characterized in terms of a combination of angle and range, the scan is converted through a kernel function to become a density-based map. Several different kernel functions can be used. With the density-based scan, the histogram can be formed to obtain an estimate of the probabilities and, consequently, (2) is used to evaluate the entropy.
Figure 4 and Figure 5 represent the original scan and the density-based scan, respectively. The entropy of the sacn in Figure 4 is evaluated to be 1.17. In contrast, the scan in Figure 6 is found to have an entropy of 0.86. Note that Figure 6 is limited in terms of its features, leading to a smaller entropy.
By evaluating the entropy of the scan, the scan-matching result can be quantified. A weighting can indeed be assigned as a function of the entropy for integration with other sensors in the integrated navigation system. A limitation of using laser scan data for the assessment of entropy is the need of the conversion to its corresponding density-based map. In vehicular navigation, a camera is often mounted together with a laser rangefinder. As a result, it is possible to use the image data from the camera for the assessment of entropy.
Figure 7 depicts the navigation system design when the context-dependent weighting is used. The navigation suite uses laser rangefinder, camera and other navigation sensors to estimate the position, velocity and attitude of the vehicle. In this approach, the reference scan is matched with the current reading scan based on the scan-matching technique to produce estimates on the rotation and translation. In the meantime, the current scan is overlaid on the image that is obtained from the camera. The region of interest, which is the image that covers the scan points, is extracted. With respect to the region of interest of the image, the entropy is evaluated. The entropy then serves as an indicator in adjusting the weighting of the rotation and translation. The use of image data is the saving in computational complexity. A potential limitation is that the entropy may be sensitive to the variation of gray scale, or RGB values may affect the result.
To verify the applicability of the context-dependent weighting, an experiment is conducted. The vehicle is equipped with the following navigation sensors for the determination of position, velocity and attitude.
In addition, a GPS real-time kinematic (RTK) receiver provides ground truth. The RTK solution is only used in the evaluation process. Figure 8 depicts the location of the sensors after installation in the test vehicle Luxgen U7.
The experiment was conducted at a test track of the Automotive Research and Test Center (ARTC), Taiwan, and Figure 9 depicts the track as well as the RTK result. The starting point is at the right upper corner of the track, and the vehicle moves in a counter-clockwise direction.
The proposed context-dependent weighting approach is evaluated. To assess the significance of the context-dependent weighting, the navigation system processes the laser rangefinder, IMU and encoder data only as these data are obtained from dead-reckoning sensors. More exactly, the GPS receiver data is not used in the processing to better quantify the contrition of the proposed approach. In practice, the GPS receiver data can be used to account for dead-reckoning sensor errors.
Figure 10 depicts the comparison of the estimated trajectory. In the figure, the RTK result is used as a reference, and the dead-reckoning results with and without the context-dependent weighting are shown. Note that when the context-dependent weighting is not used, the estimated trajectory (in red) is subject to two erroneous turns at the lower left corner and upper right corner, respectively.
The entropy as a function of time is evaluated and shown in Figure 11. Note that the entropies are relatively low at 240 seconds and 1960 seconds, respectively. These two instants correspond to the moments when the vehicle is at the aforementioned corners. Through the use of entropy-based context-dependent weighting in the dead-reckoning process, the navigation error is significantly reduced, as shown in the estimated trajectory (in blue). Thus, the effectiveness of the proposed scheme is verified.
For autonomous vehicle applications, knowledge of the current state (such as position, velocity and attitude) of the host vehicle are needed. For robust and autonomous navigation, many different sensors have been incorporated and fused to form a navigation suite. In fusing different sensor data for better accuracy and integrity, the quality of sensors must be considered. We investigated the use of a scan-matching technique for aided navigation. The context of the environment in terms of the richness of features may affect the quality of the resulting navigation system.
To address the context-dependent issue, we used a context-dependent entropy measure to assess the quality in scan matching. In addition to the increments in translation and rotation, the corresponding quality indices are obtained to better blend the scan-matching result into the navigation system. As a result, anomalous navigation results due to lack of features and improper registration can be better dealt with. The proposed scheme is experimentally verified.
The work is supported by the joint NCKU-ARTC research project, Taiwan.
JYH-CHING JUANG received a Ph.D. in electrical engineering from the University of Southern California, Los Angeles. He was with Lockheed Aeronautical System Company, Burbank, before joining the faculty of the Department of Electrical Engineering, National Cheng Kung University, Tainan, Taiwan. His research interests include sensor networks, GNSS signal processing and software-based receivers.
SHANG-LIN YU is an M.S. student in the Department of Electrical Engineering, National Cheng Kung University.
SHUN-HUNG CHEN received a Ph.D. from the Department of Electrical Engineering, National Cheng Kung University. He is with the Electronic Control Technology Group, Research & Development Division, Automotive Research & Testing Center in Taiwan. His research interests include vehicle navigation and autonomous driving.
On May 3, the first LPV-200 approaches were implemented at Paris Charles de Gaulle Airport (LFPG) — the first such approaches to be implemented in Europe. The milestone follows publication of the EGNOS-based procedures on April 28, according to the European GNSS Agency (GSA), which manages EGNOS on behalf of the European Commission.
LPV-200 enables aircraft approach procedures that are operationally equivalent to a CAT I instrument landing system (ILS) procedures. This allows for lateral and angular vertical guidance during the Final Approach Segment (FAS) without requiring visual contact with the ground until a Decision Height (DH) down to only 200 feet above the runway (LPV minima as low as 200 feet).
These EGNOS — European Geostationary Navigation Overlay Service — based approaches are considered ILS look-alike, as the LPV-200 service level is compliant with International Civil Aviation Organization (ICAO) Annex 10 Category I precision approach performance requirements, but without the need for the expensive ground infrastructure required for ILS.
“EGNOS LPV-200 is now the most cost effective and safest solution for airports requiring CAT I approach procedures,” says GSA Executive Director Carlo des Dorides. “The involvement of major aircraft manufacturers confirms that this service is a real added-value for civil aviation setting the basis for a better rationalization of nav-aids in European airports.”
The publication of LPV-200 procedures provides numerous benefits, including:
The LPV-200 Service provides European Airports with the means to implement the most demanding PBN operations as defined by ICAO,” explained ESSP CEO Thierry Racaud. “We congratulate the efforts of those involved in achieving this important milestone for the European aviation community.”
DSNA, the French Air Navigation Service Provider, pioneered these procedures as an outcome of the work co-financed by the European Union and carried out since the GSA declared the EGNOS LPV-200 service operational on 29 September 2015.
Maurice Georges, DSNA CEO, added, “The new LPV-200 approach procedures now implemented at Paris-CDG aim to demonstrate that the SBAS technology, EGNOS in Europe, is a Category I performance approach solution that is reliable. We are convinced that SBAS is a fundamental technology to modernize our navigation infrastructure. Following this first implementation, LPV-200 approach procedures will be progressively deployed over our IFR runway-ends network.”
The approach was been flown by ATR 42-600, Dassault Falcon 2000 aircraft and Airbus A350, with positive pilot feedback. “The LPV system is much more stable and more reliable in terms of safety, but also more efficient than the ILS approach. It really makes a difference,” remarked Eric Delesalle, ATR Chief Pilot, after the first LPV 200 landing on runway 26L at CDG airport.
“The accuracy and stability of the LPV guidance is really amazing, much better than with ILS. Lowering the LPV minima down to 200ft in Europe is a great improvement enabled by EGNOS, and is very valuable for business aviation operations,” confirmed Jean-Louis Dumas, Dassault Flight Test Pilot.
Future implementation. The GSA expects that by launching the first LPV-200 procedure at such an international hub as Charles de Gaulle, it will pave the way for the publication of additional LPV-200 service level procedures at other European airports. In fact, it is already confirmed that Vienna International (LOWW) is set to be the next airport to publish LPV 200 procedures.
Harris Corporation has introduced a comprehensive solution to increase the safety of drones and other commercial unmanned aircraft systems (UAS) flying at low altitudes in the U.S. The announcement was made during Xponential 2016 being held May 2-5 at the Ernest N. Morial Convention Center in New Orleans.
Harris’ ADS-B Xtend service provides critical surveillance information to help UAS operators and airspace managers to increase safety of their operations by providing them with a real-time view of other aircraft flying at low altitudes under 500 feet.
The system supplements the FAA’s existing ADS-B network, which provides precise and reliable satellite-based surveillance for the nation’s air traffic control system. The solution features a networked, dual-band receiver and relay system that can be attached to existing structures or to mobile vehicles for roaming coverage.
ADS-B Xtend expands the benefits of the company’s existing UAS situational awareness tool, Symphony RangeVue, which provides data for higher altitude flight traffic. Symphony RangeVue puts real-time FAA aircraft tracking data, flexible background maps and weather information in the hands of UAS operators through a web-hosted platform so they can make better informed decisions.
Data from networks of ADS-B Xtend relays is fused with all FAA system derived real-time aircraft surveillance data from more than 650 ADS-B ground stations with more than 425 FAA radar systems. This unique combination of local infrastructure and NAS surveillance data makes ADS-B Xtend a comprehensive situational awareness solution for the UAS market.
“Strategically deploying ADS-B Xtend receivers will close gaps in ADS-B coverage, significantly increasing the quality and quantity of data available UAS operators,” said Ed Sayadian, president, Harris Mission Networks. “This will increase surveillance data available to UAS operators and enhance safety and efficiency. ADS-B Xtend is yet another step in our commitment to develop the most comprehensive surveillance airspace data set available.”
A lot of talk is being made about UAVs these days and how this technology is going to revolutionize many industries, with surveying being one of the biggest users.
I won’t deny the impact this new tool is going to have on our profession (as written in my last column). But I don’t think it will compare to the use of GNSS technology and how it modernized measuring methods for the surveyor.
I’m often asked by young surveyors what I think is the biggest improvement experienced by the surveying profession. Ironically, I asked that same question to my teachers when I was a new survey technician. My mentors will talk of the electronic distance meter, the theodolite or the total station. (Some old timers even told me the best improvement was the gammon reel for their plumb bob or the reel for a steel “chain”!)
While these were good advancements, for me the biggest improvement was the introduction of GPS into surveying, followed by the advancement to real-time network capability. Now, coupled with modern communication methods of radio or cellular transmission to permanent base stations, the GNSS rover has become one of the most valuable tools in the surveyor’s toolbox.
To understand the importance of GNSS technology and its use by the surveying community, first take a look at the history of the profession and method/devices used for measuring. Land surveyors have been measuring boundaries of parcels for centuries, dating back to Egyptian times and workers known as “rope stretchers.” Their use of rope with knots tied at specific intervals was the measuring stick of the time period.
As centuries passed and measuring units were developed, surveyors used these dimensional tools for measuring and describing land parcels. By the time the early settlers of America began traveling westward, surveyors were using a 66-foot-long Gunter’s chain made with 100 links, each almost eight inches long. Over time the links would stretch until the surveyor’s measurements were not accurate for land surveys.
By the early 1900s, tapes made from low-expansion steel became more widely used and much more accurate for surveying. The early 1960s brought new technology with measurement systems using laser light beams with the ability to travel several miles with sufficient accuracy.
The electronic distance meter (EDM) allowed the surveyor to cover longer distances in much less time than the conventional method of the steel tape, leading to more productive field time. This technology was further refined to be installed inside of traditional theodolites to create the modern total station instrument — still used today for basic measuring of angles and distance. Almost all surveying projects can be completed using a total station, but the invention of a remotely available measuring device would be a welcome tool in the surveyor’s toolbox.
Enter the 1980s and the adaptation of the military’s satellite measuring system for civilian use. While early users and developers needed a Ph.D. in mathematics to configure its use, GPS measurement revolutionized long-distance measurement for the surveying profession. Static GPS measurement took many hours of data collection and even longer processing time, but with terrific results and with tremendous accuracy.
Further refinements with hardware and software configurations brought more affordable and user-friendly systems that gave surveying community another resource for accurate measurement. While the use of real-time kinematicc (RTK) expanded greatly in the late 1990s and 2000s, the big difference in the past 10+ years has been the introduction of real-time networks and permanent base stations. This advancement helps by eliminating the need for a base receiver and radio with an amplified repeater, and thus another employee guarding the idle base station equipment.
Depending on the surveyor’s location, real-time networks are readily available by paid subscription or through publicly funded transportation department. These systems are very reliable and don’t require a six-figure investment in equipment.
All survey data-collection methods, no matter the measuring procedure used and positional accuracy required for the project, needs to follow a strict quality-control procedure for verification of its content and position. The old adage “Measure twice, cut once” works well here, too, so let’s discuss what is involved with good measuring procedures.
Prior to any field measurements are taken, it is good practice to verify satellite availability during your planned measuring period. The U.S. GPS currently consists of 31 active and healthy units orbiting the planet and crisscrossing the sky 24/7. The geometry created by radio signals received from these satellites constantly vary in size and strength. By using mission-planning software, the user can accurately predict the best times of the day to collect positional locations with the highest accuracy and repeatability. Low numbers of satellites or strength of constellational geometry can lead to inaccurate locations and incorrect measurements between points.
The introduction and allowance of other satellite systems into our data collection system (GLONASS, Galileo, BeiDou, IRNSS) will enhance the availability and strength of constellation geometry throughout the data-collection process.
Another potential problem for GNSS data collection is solar storms, sunspots and other radio interruptions. Most manufacturers will notify the user of major atmospheric radiation events, but check the NOAA Space Weather Prediction Center (SWPC) website for updates on potential events. The key here is to plan your field collection prior to execution, in order to reduce errors in measurement or even interruptions to completing the work in a timely manner.
Survey results are only as good as the measurements, and following strict guidelines is very important. When using survey-grade GNSS equipment in a real-time function, many items need to be monitored while collecting data to ensure good quality positions. Here are items as listed by the National Geodetic Survey (NGS) in the “User Guidelines for Single Base Real-Time GNSS Positioning” manual on the NGS website:
While all of these components are necessary for quality data collection, one of the most critical steps is horizontal and vertical verification on published or previously established control points or monuments. By checking into a known point before every data-collection session, you can eliminate errors in rod/antenna height and/or coordinate system setup. Checking a known point can also help determine if the correction signal is providing accurate information, either from the RTK base station or as part of a subscription service via cellphone or radio. It will also help discover poor PDOP or RMS due to weak satellite configurations. Also, if the rover unit takes longer than usual to initialize, a potential data-collection issue may occur to bad conditions.
The biggest complaint I get (and see) is field crews not checking the accuracy of the GNSS unit during the course of a survey. Hopping out of the vehicle, firing up the data collector, and taking a measurement multiple times without redundant measurements or verifying existing control points/monuments is a recipe for disaster.
Here are my keys to successful data collection with GNSS technology:
While GNSS has greatly decreased field time for covering large areas quickly, it must still be used correctly in order to provide accurate positional locations. The accuracy of these positions are what the measurements of the surveyor relies upon, and they must meet a high standard of confidence. Our profession prides itself on being called upon as the “expert measurer,” so our methods of measurement must be up to those standards.
While it took a little time to get the cost-effectiveness, reliability and user friendliness to a level of affordability for the surveyor, GNSS has become one of the best tools in our toolboxes. GNSS has revolutionized modern surveying, and I, for one, appreciate its ability to help me offer my services as an expert measurer.
Leica Geosystems has announced the Leica Viva GS16 survey receiver, along with updated Leica Captivate and SmartWorx Viva software.
The GS16 is a “self-learning GNSS receiver,” the company said, able to automatically select the optimal combination of GNSS signals and stay connected with or without reference links.
The new release enhances the Leica Captivate Experience released in 2015. The addition of self-learning GNSS is accompanied by increased lock-on capability in the multi-station and various upgrades to the immersive Captivate software.
With a robust 555-channel engine, the new receiver is empowered by RTKplus to access all known and current signals, while intelligently distinguishing which ones are the optimal combination to lock onto for accurate positioning adapting to any environmental conditions.
The GS16 also has capacity for future signals, such as the full deployment of BeiDou and the expected progress of Galileo and QZSS. With SmartLink, a precise point-positioning technology, uninterrupted positioning continues even when local correction services are unavailable because of obstructions or lack of cellular coverage. Even when no reference data is available, SmartLink continues to enable fully remote work.
Embedded with the touch technology of the Leica Captivate measurement software, users can now bring the 3D experience from their total stations and multi-stations directly into their GNSS workflows. Cumbersome and time-consuming calculations and conversions are no longer needed with a direct link between self-learning total stations and multi-stations and the new self-learning GNSS receiver.
On a field tablet or controller, users can interact with immersive 3D models directly in the field, ensuring all data is collected and linked to the office, eliminating the need for return trips to the field.
“When we developed the Viva GS16 receiver, we drew on 30 years of experience in GNSS to make the best receiver we have made to date,” said Bernhard Richter, Leica Geosystems GNSS business director. “With its flexible design, this receiver is a safe investment for the future while also bringing immediate benefits using the new GNSS signals and SmartLink.”
In addition, Leica Captivate v2.00 and SmartWorx Viva v6.00 have also been released. This upgrade brings Dynamic Lock, the increased lock-on capability of ATRplus in the MultiStation. Now significantly enlarging the search area for locking onto a moving target, the MultiStation can be used in standard surveying or high-dynamic machine control applications for better performance.
This upgrade also brings a long-range Bluetooth capability for the Leica CS35 tablet, enabling long-range control for robotic total stations and more flexibility on any site. Users can now also position and orient a total station to any object, allowing use on a moving platform for increased mobility.