ArduSimple has announced the availability of a range of GNSS starter kits for anyone in Europe or the United States who is interested in testing or integrating high-precision centimeter accuracy for a service or product proof of concept (PoC).

Building a PoC for increasingly common applications such as autonomous vehicles, where high levels of positioning accuracy are required, is often a complex process. Finding compatible antennas that are tuned correctly, CPUs, modems that connect to GSM, sourcing a global SIM, finding a suitable real-time kinematic correction engine that works in multiple regions, and mounting it all on a board is a lengthy and costly process, according to ArduSimple.

To solve this issue, ArduSimple pulled together the components and services required into a range of starter kits that work out of the box. The simpleSSR Starter Kit  works anywhere in Europe and the United States that has a 4G signal.

“Bringing together the components, high-precision accuracy and connectivity in Europe and the United States in one simple out-of-the-box solution will significantly speed up the process of PoC projects,” said Marc Castillo, senior consultant at ArduSimple. “We’ve reduced the complexity, enabling engineers to focus on the feasibility of their projects.”

The kit includes:

• 1 simpleRTK2B-F9P V3 board
• 1 u-blox ANN-MB-00 Antenna for GNSS Dual Band with cable (IP67)
• 4G radio module with NTRIP client including RTK-SSR engine (XBee socket compatible)
• 2x 4G antennas with integrated cable
• 1x SIM card with 1-year subscription
• 1-year subscription to SSR service

Inertial Labs has announced new versions of its Kernel inertial measurement units (IMUs).

The Kernel 110, 120, 210 and 220 are a set of compact, self-contained, strapdown industrial-grade (100 series) and tactical-grade (200 series) IMUs that measure linear acceleration and angular rates with three-axis micro-electromechanical (MEMS) accelerometers and three-axis MEMS gyroscopes.

Fully calibrated, temperature compensated, mathematically aligned to an orthogonal coordinate system, the Kernel 210 and 220 contain 1 deg/hr bias in-run stability gyroscopes and 0.005 mg bias in-run stability accelerometers.

The new Kernel 110 and 120 IMUs will be superseding the existing Kernel 100 IMU. The Kernel 210 and 220 are  miniaturized versions of the company’s IMU-P (Professional) tactical unit.

The Kernel series of inertial measurement units are a fully integrated inertial solution that combines the newest MEMS sensors technology. This seamless integration allows Inertial Labs to provide an inertial system with high performance while maintaining a high-value price point. With its compact design and low power consumption, the Kernel IMUs easily integrate in a wide range of higher order systems while consuming very little space and power.

With continuous Built-in Test (BIT), configurable communications protocols, electromagnetic interference (EMI) protection, and flexible input power requirements, the Kernel 110, 120, 210 and 220 are built to be used in a wide variety of environments and integrated system applications. Units have been thoroughly tested to perform in large variations in temperature, high vibration, and shock.

Designed to be used in air, marine and land environments, the Kernel series can be integrated into motion reference units (MRU), attitude and heading reference systems (AHRS) and GPS-aided inertial navigation systems (INS). As a result, Kernel IMUs are suitable for a wide variety of applications such as autonomous vehicles, antenna and line-of-sight stabilizations systems, as well as buoy or boat motion monitoring.

“The new Kernel IMUs represent the innovative approach at Inertial Labs,” said Jamie Marraccini, president and CEO of Inertial Labs. “The high performance and the flexibility to integrate into different systems and applications is what we have striven to provide to our clients with the new Kernel IMU release.”

GPS positioning for navigation and mapping is challenging in urban environments, where GPS signals often are blocked by tall buildings. The following three papers — to be presented at the Institute of Navigation (ION) GNSS+ conference Sept. 19–23, 2022 — explore ways to solve that problem. The full papers will be available at www.ion.org/publications/browse.cfm following the conference.

ALGORITHMS FOR URBAN MAPPING

In this work, the authors use an urban environment model incorporating visibility predictions and remote-sensing techniques, which they tested in a sensor-equipped vehicle in Denver. They use an interacting multiple model (IMM) filter that uses extended Kalman filters to build and verify a map of the signal environment in an urban-canyon setting. The techniques will give ground-vehicle operations the ability to plan for blocked and delayed signals for global path planning.

Zeller, Emma; Strandjord, Kirsten, University of Minnesota; and Wang, Pai, Shanghai Jiao Tong University; “Algorithms for Mapping the Urban Signal Environment for Navigation of Ground Vehicle Operations.”

ADDING VISUAL TO GNSS/INS

GNSS real-time kinematic (GNSS-RTK) positioning is a key technology for surveying and mapping applications. To extend the capability of GNSS in difficult environments, a tight coupling between GNSS-RTK and an inertial navigation system (INS) can greatly improve the results. If the time spent in a GNSS outage is too long or if the kinematic of the survey is too weak, the GNSS/INS solution can be compromised with high navigation errors, ultimately making it impossible to align the heading angle at initialization.

This paper presents an innovative solution to overcome GNSS/INS limitations, minimizing system complexity by using a tightly coupled GNSS/INS solution with a monocular visual inertial SLAM system. This solution is capable of initialization in a few seconds and is very reliable in the long term. This vision/INS/GNSS coupling increases the overall RTK fix rate and broadens the availability of high-precision navigation solutions under challenging conditions.

Bénet, Pierre; Saussay, Brice; Saidani, Mourad; and Guinamard, Alexis; SBG Systems; “Tightly Coupled Inertial Visual GNSS Solution: Application to LIDAR Mapping in Harsh and Denied GNSS Conditions.”

USING 3D BUILDING MODELS

To solve the urban-navigation challenge, the authors propose using a 3D building model to assist GNSS positioning. This type of algorithm is named the 3D building model aided GNSS (3DMA GNSS). It can predict measurement errors and the visibility of the satellites, as line-of-sight or non-line-of-sight. The solution is then derived from the likelihood of the observed and predicted measurements over candidate locations.

The authors propose an innovative method for evaluating the reliability of building models based on the awareness of sky visibility in a specific geographic context. Sky visibility estimation is improved with use of a support vector machine regression and considering low-Earth-orbit (LEO) constellations. The real-time sky visibility could present the update of the surrounding buildings, whereas the predicted sky visibility based on the existing building models remains unchanged. Making use of this inconsistency, the authors could identify areas with the updated building. Additionally, the impacts of the building update monitoring on the 3DMA GNSS are evaluated in an urban canyon.

Xu, Hao-Sheng and Hsu, Li-Ta; Department of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University; “Urban Buildings Update Monitoring Based on Sky Visibility Estimation using GNSS and LEO.”

A roundup of recent products in the GNSS and inertial positioning industry from the June 2022 issue of GPS World magazine.

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SURVEYING & MAPPING

Base/Rover

For survey-grade GNSS accuracy anywhere

A base/rover feature built upon the Flex GNSS receiver brings affordable centimeter-level accuracy to surveyors and geospatial professionals working anywhere in the world. The solution consists of two Flex GNSS receivers and two UHF radios, allowing customers to perform high-accuracy field data collection in areas where traditional real-time kinematic (RTK) corrections or cellular coverage is not available. Existing Flex customers can upgrade by adding Flex radio kits (pictured). The Bad Elf Flex enables data collection either as a standalone receiver or paired with apps on iOS or Android phones and tablets.

Bad Elf, bad-elf.com

Mobile Mapper

Preserves privacy with artificial intelligence

The Leica Pegasus TRK reality-capture mobile-mapping system features artificial intelligence (AI), autonomous workflows and intuitive interfaces. To comply with privacy regulations, its AI can identify and blur identifiers, such as people and vehicles, in real time. Features include advanced dynamic laser scanning and an expandable imagery system for recording, measuring and visualizing. It enables long-range mobile mapping for asset management, road construction, rail, critical infrastructure, utilities and more. The system also can create high-definition basemaps for autonomous vehicles.

Leica Geosystems, leica-geosystems.com

Imaging System

Delivers colorized products with high accuracy

The True View 645/650 is the latest 3D Imaging System (3DIS) from GeoCue. Combined with the True View EVO data-processing software suite, it includes the full post-processing software workflow and directly integrates with Applanix POSPac. EVO supports the creation of project deliverables including ground classified point clouds, surface models, contours, digital elevation models (DEMs), volumetric analysis and wire extraction. The system delivers colorized lidar deliverables with accuracy better than 3 cm root-mean-square-error (RMSE) for the True View 645, and better than 2 cm for the True View 650.

GeoCue, geocue.com

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OEM

Front-End Receiver

Software-defined receiver front-end

The Eagle-2 works with software-defined receivers in real time or records GNSS signals for post-processing. For post-processing, Eagle-2 supports most third-party receivers, such as MATLAB and C/C++ receivers. The front end allows a user to work with two perfectly synchronized channels connected to two antennas. The Eagle-2 supports GPS, Galileo, GLONASS , BeiDou, QZSS and SBAS.

IP-Solutions, www.ip-solutions.jp

Helical Antennas

Feature extended filtering of interference

The housed HC885XF and embedded HC885EXF dual-band eXtended Filtering (XF) antennas receive GPS/QZSS L1/L5, GLONASS G1/G3, Galileo E1/ E5a/b, BeiDou B1/B2/B2a and L-band corrections services. They have been tuned to provide optimal support for the entire L1/G1/E1/B1/L-band correction and L5/G3/E5/B2 bands. The housed version, HC885XF, weighs ~42 g and is enclosed in a robust, military-grade IP67 plastic enclosure. The embedded version, HC885EXF, weighs ~8 g and is easily mounted with an embedded helical mounting ring.

Tallysman Wireless, tallysman.com

Converter

Sets performance benchmarks for harsh environments

The AD9213S-CSH is a highly integrated RF analog-to-digital converter that handles 12-bit, 10.25-giga-samples per second. It is the company’s fastest ADC available for the space environment. The AD9213-CSH enables the next generation of software-defined systems for satellite communications, radar and remote sensing. The high sample rate and integrated post-processing enable further performance gains for narrow-band applications.

Analog Devices, www.analog.com

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UAV

Ebook

Provides guidance to achieve corporate buy-in

Skyward has published a free ebook, Adding Drones to the Enterprise, to provide guidance on establishing a corporate drone program. According to Skyward, the most efficient and effective drone programs are the lowest risk and most compliant. Topics covered include how to present the business value of a drone operation to corporate executives; how risk managers can optimize the workflow to ensure maximum safety; best practices for risk mitigation and regulatory compliance; tips for collaborating with legal and compliance teams on a general operating manual; and how to provide full transparency to corporate stakeholders.

Skyward, https://go.skyward.io/adding-drones-to-the-enterprise-ebook.html

Enterprise System

Includes drone, fleet software and charging dock

DJI’s all-in-one solution for professional drone operators includes the DJI Matrice 30 (M30) drone integrated with DJI FlightHub 2 fleet-management cloud software and DJI Dock for autonomous docking and recharging. The integrated solution is suitable for Enterprise drone users such as public safety agencies, infrastructure inspectors and energy operators. The M30 model is designed for rugged professional uses, while the fact that it fits in a backpack makes transportation and setup fast. The DJI Dock is an autonomous takeoff, landing and charging station allowing fully automatic, programmed flights with the DJI M30 Series (Dock Version). After setup, the fully charged M30 drone can take off from the dock through FlightHub 2 programmed automatic missions anywhere within a seven-kilometer radius.

DJI, www.dji.com

Airborne Lidar

Easily installed on various UAV platforms

The AlphaAir 1400 (AA1400) and AlphaAir 2400 (AA2400) lidar systems are lightweight, compact airborne scanners easily installed on various UAV platforms or small survey aircraft and helicopters. They are adapted to high-density point-corridor mapping applications, day or night, under leaf-on and leaf-off conditions or with dense vegetation to provide reliable results. Combined with industrial-grade GNSS receivers and high-precision inertial measurement units (IMUs), the AA1400 and AA2400 provide 2 cm to 5 cm survey-grade accuracy. They also integrate Riegl VUX lidars with waveform-lidar technology, allowing echo digitization and online waveform processing.

CHC Navigation, chcnav.com

Autopilot

Provides built-in redundancies

The VECTOR-600 is a robust, dependable autopilot with built-in physical and logical redundancy, allowing it to survive all individual sensor failures while maintaining accurate estimates of attitude and position. It works for fixed-wing, rotary-wing and vertical-take-off-and-landing UAVs. It provides exceptional performance in GNSS-denied environments and when there is a jamming threat. The VECTOR-600 features high quality components and an electromagnetic-resistant design tested to MIL-STD 461.

UAV Navigation, uavnavigation.com

Surveillance System

Ground-based solution enables safe operations

Casia G is a ground-based detect-and-avoid surveillance solution that provides 360° optical detection with alerts. It enables operators to avoid both cooperative and non-cooperative aircraft for safe beyond-visual-line-of-sight (BVLOS) flight. Casia G creates a perimeter of monitored airspace for UAVs to perform work safely, without additional payload. It is suitable for operations in fixed or temporary locations, supporting drone-in-the-box operations and augmenting or replacing human visual observers. Casia G sees the entire sky, with uniform probability and resolution, 10 times per second, covering a majority of small UAS use cases.

Iris Automation, irisonboard.com

ION is now accepting abstracts for the co-located 2023 International Technical Meeting (ITM) and Precise Time and Time Interval (PTTI) Systems and Applications Meeting. The co-located conferences will take place January 23-26, 2023 at the Hyatt Regency Long Beach, in Long Beach, California.

ION strongly encourages authors to present in-person in Long Beach. Authors will be given the option at the point of abstract submission to submit for “in-person presentation with video presentation for remote viewers” or “virtual presentation only.”

The Precise Time and Time Interval Systems and Applications (PTTI) meeting is an annual conference sponsored by ION with a technical program designed to disseminate and coordinate PTTI information at the user level, review present and future PTTI requirements, inform government and industry engineers, technicians, and managers of precise time and frequency technology and its problems, and provide an opportunity for an active exchange of new technology associated with PTTI.

ION’s winter meeting, the International Technical Meeting (ITM), is a more intimate conference with a technical program related to positioning, navigation and timing and includes the ION Fellows and Annual Awards presentations.

Abstracts are due October 7 and can be submitted at https://www.ion.org/itm/call-for-abstracts.cfm.

Will GPS modernization and improvements in GPS receivers and antennas reduce or even eliminate the need for correction services for most applications?

“For most applications, I think the answer is yes, the need for correction services will be reduced. When you can get <1m without external corrections, the majority of conventional accuracy requirements are fulfilled. However, increases in accuracy always open up new applications for GPS, so correction services will still be required.”
— Julian Thomas
Racelogic

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“Correction services will continue to be in demand for those markets and applications requiring precision and accuracy below a few inches, 2-3 sigma confidence levels and high reliability, availability and integrity. While ionospheric errors have been low in the past 15+ years, correction services will also provide ionospheric models beneficial in periods of higher activity. Even as there are improvements in user equipment and signal modernization, the demand for correction services will increase in line with these improvements and new functionalities to enable more markets and applications worldwide.”
— Miguel Amor
Hexagon’s Autonomy & Positioning Division

Precision agriculture refers to the ability of farmers to observe, measure and respond more precisely to the variability of soil and crop characteristics within and between fields by using maps of these characteristics and GNSS navigation. It enables them to reduce inputs of seed, water, fertilizer, pesticides and fuel while increasing outputs. Adoption of precision agriculture technology and practices has increased steadily over the past three decades and now covers the majority of U.S. farmland.

We asked three companies that manufacture GNSS receivers optimized for precision agriculture about their challenges and plans.

— Matteo Luccio, Editor-in-Chief

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HEMISPHERE GNSS

Roland Moelder, Product Manager

What are the key challenges for precise positioning in agriculture?

One of the main concerns is the impact of obstructions — both natural, such as tree canopy and topographies, and manmade, such as buildings, silos, etc. The mounting location of the GNSS antenna on an agricultural vehicle or implement can emphasize multipath effects and limit GNSS signal availability.

Our solution for these challenges is the use of a multi-frequency receiver. In this case, the increased number of tracked GNSS signals (from GPS, Galileo, GLONASS and BeiDou), as provided by the latest Hemisphere GNSS technology used with the A631 Smart Antenna product, allows the receiver to overcome challenging conditions to ensure a stable and robust positioning solution. For example, if a tree line blocks a part of the sky at the headland of the field, it can be compensated for with additional satellite signals available outside of the blocked area, so that guidance, automated steering and application control are not interrupted. Dust and vibrations are not an issue for us due to the rugged design of the A631 GNSS Smart Antenna. However, depending upon the radio link used, long-distance RF communications for real-time kinematic (RTK) corrections can become a limiting factor. In this case, we often propose using RTK corrections over NTRIP or considering our Atlas L-band correction service for the as an RTK-like alternative.

What is the requirement for start-up time?

Although farmers spend hours in the field during the season, the planting and harvesting windows are limited; therefore, time is critical. The requirement from farmers is to be ready to go when they start their machine. During busy times in the season, farmers often leave their equipment in the field, so startup times may only be a few minutes. We meet this requirement with our startup times for SBAS and RTK corrections and the Atlas AutoSeed feature for L-band corrections. Atlas AutoSeed allows users to suspend Atlas use for any period of time, and upon returning to their last location, the Atlas system uses AutoSeed to rapidly reconverge to a high-accuracy converged position.

What is the accuracy requirement for planting?

Especially row crop planting over what we refer to as broad acre farming requires accuracy to within a few inches, which we offer with our Atlas H10 correction service. Depending upon the farming practices used (such as controlled traffic or inter-row applications), these demands are not only for accuracy, but also for repeatability of the positioning solution.

Another area that demands high accuracy is the production of specialty crops. Per our experience, this farming practice requires sub-inch accuracy and repeatability, which we meet with our RTK solutions.

What is the difference between Atlas and Atlas Basic?

We think of Atlas Basic as a global solution comparable to the different regional offerings for SBAS corrections in terms of accuracy. This means a radius 95% pass-to-pass (R95 P2P) accuracy of around 30 cm with absolute accuracy in the submeter area. We feel that this meets the “basic” needs for all precision agriculture applications.

If a customer is looking for higher accuracies, we offer the H30 and H10 Atlas Correction Services. For comparison, Atlas H30 provides R95 P2P accuracy of 15 cm, and H10 provides R95 P2P accuracy of 4 cm.

Besides your GNSS receivers and corrections services, what hardware, software and services do you provide for precision agriculture?

We announced our new MaveriX precision agriculture solution in September 2021. It uses our recognized A631 Smart Antenna and provides a complete precision agriculture solution combined with the M7 and M10 terminals, eDriveM1 steering controller, ESi2 electric steering wheel and AC110 application controller. The MaveriX precision agriculture application software, which runs on our MaveriX terminals, is the centerpiece of the system. The first production systems are being used by customers in North America this spring.

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CHC NAVIGATION

Ling Hu, Precision Agriculture Business Development Manager

What are the key challenges for precise positioning in agriculture?

Normally in the agricultural field, the environment is harsh (mud, slopes, shocks), which requires the system to be rated IP65 and above and vibration resistant. In some areas, the signal coverage of cellular phones may be insufficient. When that is the case, a UHF modem-type communication is more commonly used with a distance constraint related to the propagation of UHF signals, strongly related to the quality of the installation of the GNSS base station (height of the UHF antenna, gain, immediate environment of the station). Our NX510 SE overcomes that issue by integrating two communication modes, 4G and UHF.

Is planting the application that requires the highest accuracy? What accuracy can you consistently provide?

Certainly, planting requires the highest accuracy of 2.5 cm from pass to pass. With a stable GNSS RTK correction, centimeter accuracy can be provided reliably.

What is the requirement for startup time? What do you deliver?

The startup and initialization of the system should take as little time as possible and is usually done within 1 to 2 minutes from cold start. Farmers usually start their system when they drive the tractor out of the shed and are therefore ready to work as soon as they arrive in their field. Warm start (reacquisition + RTK fixed) is more important in case of obstacles or loss of the RTK correction used by the customer, when using the auto-steering/guidance system in the field. It is typically about 10 seconds.

Besides your GNSS receivers, do you provide any additional hardware, software or services (such as support and training) for precision agriculture?

Our NX510 autopilot kit consists of a receiver, display, motor, angle sensor, camera and accessories, so users can start working immediately without purchasing additional options.

In addition to automated steering systems, CHCNAV also provides complementary solutions that allow farms to be autonomous in terms of GNSS RTK corrections. These solutions consist of GNSS base stations with an integrated or external radio modem and GNSS NTRIP stations for connection over 4G. Individual GNSS stations can be networked using our CPS Net software, which can be operated by a group of farmers, agricultural cooperatives or tractor dealers. Training and user support is provided by our network of authorized agricultural resellers to ensure the closest possible service to our users.

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HARXON

Wang Xiaohui, Technical Director, Antenna Department

What are the key challenges for precise positioning in agriculture?

Obtaining accurate position information in real time requires real-time kinematic (RTK) positioning. There are many ways to obtain differential data. One is to establish a reference station and broadcast differential data through short-distance communication methods. This method’s disadvantage is the high cost of stations and the limited transmission distance. Another is to broadcast RTK data through an LTE network. This is convenient, but if the LTE signal coverage is poor, RTK positioning may not be achieved. A third method is to rely on satellite-based augmentation. This is independent of ground communication equipment, but has a relatively long convergence time and may be greatly affected by signal occultation.

Agricultural machinery must work in harsh environments, such as extreme heat, severe cold and strong vibrations. Consequently, the antenna must be enclosed in a robust housing with excellent protection to guarantee long-time outdoor work.

When agricultural machinery operates near densely packed and tall trees, positioning accuracy will be significantly affected. Limits on the size and cost of antennas for agricultural machinery prevent the use of choke-ring structures. Therefore, the key to achieving high-precision positioning lies in how to receive more satellite signals and avoid multipath interference in a small antenna size.

How can the antenna help with these challenges?

Harxon’s X-Survey antenna is highly integrated and multi-functional. It embeds antennas for GNSS (GPS, GLONASS, BeiDou, Galileo, QZSS, NavIc, other regional systems and SBAS), 4G, Bluetooth/Wi-Fi 900M/2.4G radio, and other frequencies. The X-Survey enables users to choose the most appropriate way for them to acquire differential data — LTE, Wi-Fi, radio or SBAS — making high-precision positioning possible in most environments.

Harxon has designed many high-precision antennas with different structures for various application environments, including those that are waterproof and dustproof and those that can withstand very high and low temperatures and violent vibrations.

Additionally, Harxon’s antennas adopt unique cross-polarization suppression technology, with good circular polarization characteristics, providing effective suppression performance for multipath signals.

How does Harxon support TerraStar correction services?

Harxon’s TS112 PRO Smart Antenna provides reliable positioning solutions for agricultural automatic guidance. It can obtain RTK-level positioning information by receiving correction data from the embedded UHF radio or its GSM modem. Also, TS112 PRO embeds a Hexagon | NovAtel OEM GNSS module, and TerraStar multi-constellation corrections are available globally on this compatible module. TerraStar corrections are available as a termed subscription from Hexagon | NovAtel.

By Markus Irsigler and Sebastian Kehl-Waas

Interference-free GNSS signals are essential for more than just military vehicles and aircraft. Anti-jam systems usually suppress signals from interference sources by means of spatial filtering.

These solutions can likewise be used to protect satellite navigation signals for autonomous driving and flying against interference signals. To allow GNSS receivers to detect interference sources and suppress transmitted interference signals, they must be designed as multichannel systems.

This way the direction of the interference signal can be determined using phase-coherent signal processing of signals from multiple antennas, and the interference can be suppressed. Rohde & Schwarz offers a solution for the verification of interference immunity and interference suppression.

Multi-channel receivers can simultaneously process signals from multiple distributed antennas or from an antenna array. This is useful for determining the direction of incoming signals by means of signal analysis, and for adjusting the antenna pattern so that undesired signals are suppressed. For GNSS-based position determination, this means that signals from global navigation satellite systems (GNSS) can be strengthened and jamming or spoofing signals originating from the ground or the air can be suppressed. Up to now this technology has primarily been used for military applications, but in the future it can also make an important contribution to robust navigation for autonomous driving or flying. Typical interference sources in this regard are harmonics of transmitters in the vicinity, tactical air navigation (TACAN) signals, DME air navigation signals for civil aviation, and LTE signals. Another factor is the growing popularity of so-called personal privacy devices (PPD), which are GNSS jammers that radiate narrowband or broadband signals to disrupt GNSS localization. A new solution from Rohde & Schwarz enables comprehensive testing of the resistance of GNSS receivers to interference signals, if necessary in a realistic hardware-in-the-loop (HIL) environment.

Multi-Channel GNSS Receivers for Interference Suppression

GNSS receivers often use controlled reception pattern antennas (CRPA) to suppress undesired signals. These antennas consist of an antenna array and a signal processing unit. The connected antennas are generally arranged in a strict geometric pattern to achieve full coverage of all possible signal directions. The overall receive characteristic of the antenna array can be altered by suitable weighting of the signals from the individual antennas in the signal processing unit (Fig. 1). This way, interference signals can be specifically blanked out (nulling) or the required GNSS signals can be amplified at their angle of arrival (beamforming). A combination of these two methods is also possible. The antenna arrays typically consist of four to seven elements. The number of interference signals that can be simultaneously suppressed increases with the number of elements.

Test System Requirements

Rohde & Schwarz offers a test system for GNSS receivers that use CRPAs. First, it acts as a multichannel GNSS simulator that considers all aspects of a satellite navigation system. It must be able to generate the signals of all standard satellite navigation systems in all GNSS frequency bands, with attention to correct satellite orbits, signal propagation characteristics and realistic modeling of the dynamically changing receive environment. Configuration of the antenna array in terms of geometry and the receive characteristics of the individual antennas also must be included.

Simulating the Interference Signals

Second, the system can simultaneously generate jamming or spoofing signals in order to test the interference suppression functions of the device under test (DUT). A second, identical test system is necessary for freely definable configuration of interference sources with very high transmit power. Here the R&S Pulse Sequencer software assists in the definition of complex interference scenarios. The scenarios cover requirements such as long simulation times, moving interference sources and GNSS receivers, user-defined antenna patterns and antenna scans. In addition, the software calculates the correct amplitude, phase angle and propagation time of the signals as a function of signal frequency, antenna arrangement, and the positions of transmitters and receivers in three-dimensional space for each individual antenna element. Signal generation is handled by the R&S SMW200A high-end vector signal generator.

For the tests, the required GNSS signal as well as the unwanted interference signals must be generated for each antenna input of the GNSS receiver. In order to test a CRPA receiver with four antenna inputs, this means that four signal sources are needed to generate the GNSS signals and an additional four signal sources are needed to generate the interference signals. Fig. 2 shows a pair of test systems that can be used to generate coupled GNSS signals and interference signals for a four-channel CRPA receiver.

Calibration Against the DUT

In order to correctly simulate the directions of the satellite signals and the interference signals, the test systems must be calibrated at the RF interface to the DUT with regard to amplitude, phase and propagation time. This means that the amplitude, phase and propagation time differences between the individual RF paths, resulting for example from cables or RF components, must be compensated. The vector signal generators of each system are phase coherently linked using suitable synchronization. A high-end R&S SMA100B analog signal generator in each system provides the shared LO signal.

Using the R&S RF Ports alignment software, the complete system can be calibrated at any desired reference plane with regard to amplitude, phase and propagation time, so that the properties of the test system do not corrupt the simulated signal differences between the individual antennas. The required measurements are performed with a vector network analyzer.

It is not necessary to calibrate the two test systems relative to each other. For the simulation of realistic scenarios, it is sufficient to run the GNSS and interference source simulations at the same time, since in the real world there is usually no correlation between GNSS satellites and interference sources.

Integration in an HIL Environment

The GNSS test system also can be embedded in a hardware-in-the-loop (HIL) environment. In this case a computer streams the motion profile of the GNSS receiver under test, with position, speed, acceleration and vehicle attitude, to the test system at a high data rate. The test system then generates the corresponding satellite navigation signal in real time. This requires very high update rates and low latencies.

Summary

Multichannel GNSS CRPA receivers considerably improve the navigation of ground vehicles and aircraft of all kinds. With the new Rohde & Schwarz test system, realistic multi-channel test signals can be generated for both GNSS simulation and interference simulation. For tests in an HIL environment, motion data also can be streamed to the GNSS test system.

Plus: UAVs in Ukraine, vineyard protection and a royally awesome light show

Taser-equipped drones

We hear of mass shootings in schools, and this week on a crowded street in Philadelphia a school adviser was among those killed. Everyone continues to be outraged, but as we wait for any sort of positive, preventive action by our leaders, an idea from a drone developer was shut down before it even got out of the company.

Axon Air supplies Tasers and body cameras to police forces, and last year someone came up with the idea of loading a drone with a Taser so that it could find and suppress a gunman in a school. There are a lot of problems with the idea, and Axon’s own internal artificial-intelligence board nixed the idea.

Doors were the board’s primary concern. What happens if something triggers a drone to Taser kids in the classroom or hallway? Could autonomous drones or even multiple intelligent cameras detect an actual weapon of any description, and set off an automated response?

We use metal detectors on entry to some schools to deter carrying weapons to class, but how about recognizing carried weapons in the school? To even attempt an automated drone response, you would need multiple Taser-equipped drones in all areas of a school, as well as time to test and verify that any autonomous response would work correctly.

Could anything along these lines be something we might consider in any way?

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Keeping watch at vineyards

A team at Washington State University (WSU) has come up with a new twist on an old idea. Hawks have been trained effectively in the past to chase off flocks of birds on or around runways at airports or to protect crops. Now WSU has developed a system that uses intelligent cameras to detect birds, and which is then able to dispatch drones to the invaded area to chase off the birds.

The system has been tested to protect local grapevines. Bird fruit losses were actually reduced by ~50% following manual drone flights, which also reduced the number of bird invaders four-fold.

Nevertheless, birds can learn over time how to get round such deterrence, so WSU proposes disguising drones as predator birds and arming them with distress calls or raptor-attack behavior. WSU is looking for wine-industry support to develop this approach into a feasible, deployable solution.

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Grey Eagles might fly in Ukraine

The U.S. is considering providing Grey Eagle UAVs (the Army version of the Predator) to Ukraine — the first time a relatively high-tech drone with weapon-carrying capability would be supplied for the Ukrainian conflict.

The Grey Eagle can carry up to eight hellfire missiles, fly for 30 hours at relatively high altitude, and gather masses of surveillance information — a formidable, front-line weapon/reconnaissance system. Four UAVs are envisaged; missiles would not be included in the first round, but would likely come soon after.

Th Grey Eagle UAV system usually requires months of advanced training, but the Ukrainian forces have already been operating the smaller missile-carrying Turkish Bayraktar-TB2, so training may be reduced to a few weeks for operational necessity. Meanwhile, the sale must first be approved by Congress, so nothing is yet certain.

Before the war with Russia, Ukraine purchased up to 30 TB2 drone systems, and many have seen action in the current conflict. A crowdfunding effort by a TV station in Lithuania gathered enough cash to buy yet another TB2 to help Ukrainian forces stay in the fight.

However, Baykar, the Turkish manufacturer, declined the sale, instead offering to donate a TB-2 so that the Lithuanian funding could go toward humanitarian aid for the Ukrainian people.

Meanwhile, in Estonia the Internal Security Service (KAPO) arrested a man leaving the country who is suspected of supplying commercial drones to the Russian forces.

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Honoring the Queen

Finally — on a much lighter, respectful note — a drone light show was a big hit over Buckingham Palace in London on the occasion of the Platinum Jubilee concert for Queen Elizabeth II.

The queen has been on the throne in the United Kingdom for 70 years. To celebrate, the Brits hosted a major shindig. As part of a concert held outside Buckingham Palace, 400 lightshow drones from SkyMagic flew above the palace. The drones created various designs, showing the message “Thank you, ma’am”, a Corgi, a handbag, a teapot pouring into a teacup, guards in busbies, and a figurehead postage stamp — all good fun received in good spirit by a huge milling crowd.

Food for thought

To sum up, maybe it’s not such a good idea to have drones equipped with Tasers in schools, but perhaps it’s an idea we could build on to better protect our kids.

Trained, autonomous drones that take off and chase birds when they descend on vineyards — could this be a better solution than low-slung netting?

The war in Ukraine rages on. Not only the West, but also some Eastern countries pitch in with support.

Finally we saw a drone light show for the queen during the Jubilee celebration of her 70 years reign. We’re seeing a lot of smart drone potential out there.