Galileo and EGNOS were the focus of attention at a special workshop at this year’s Intergeo in Stuttgart, which took place in September. Intergeo is the world’s leading conference and trade fair for geodesy, geo-information and land management.
Intergeo provided an opportunity to give an update on the status of the Galileo and EGNOS programs and to present user case studies at a special workshop focusing on the geomatics market.
In his presentation at the conference, Eduard Escalona, Market Development Innovation Officer at the European GNSS Agency (GSA), stressed the key role of GNSS.
“GNSS is a cornerstone in many areas: It is a fundamental element for cadastral surveying, in the construction sector, in mining, land surveying and mapping activities, for all geographic information systems (GIS), for infrastructure monitoring and for marine surveying. For all of you who are working in these and many other areas, Galileo is now helping to provide the GNSS services you need,” he said.
Dual-frequency boosts market
The European GNSS programs, Galileo and EGNOS, continue to move forward in terms of adoption by the professional market and among general users, thanks in no small part to the development of dual-frequency capability.
Traditionally, mobile, location-based applications have been powered by single-frequency GNSS receivers operating under stringent battery-power and footprint constraints. With a dual-frequency chipset, these devices now benefit from better accuracy, ionosphere error cancellation, improved tracking and better multipath resistance.
Galileo is leading the way in the area of dual-frequency signal delivery, now with more dual-frequency operational satellites in orbit than any other GNSS system. Market uptake of Galileo receivers has been impressive; in addition to the geomatics-related areas of particular interest to the Intergeo public, dual-frequency GNSS chipsets are also appearing in the automotive sector, where connected cars and autonomous vehicles present a clear and pressing need for accurate and reliable positioning information.
New services to come
“To date, more than one billion Galileo-enabled devices have been sold,” said Escalona, “but Galileo isn’t standing still, waiting. We are proposing new services to appear in the coming years.”
These include the much-anticipated High-Accuracy Service (HAS) and a new Authentication Service. “The HAS will be a free, globally available service providing an accuracy of 20 cm, with PPP [Precise Point Positioning] corrections,” Escalona said.
Meanwhile, the Authentication Service (OS-NMA) will provide protection against jamming, spoofing and meaconing on the E1B signal and a separate Signal Authentication Service (SAS) will provide an even higher level of protection on the E6 signal.
“EGNOS is currently working with GPS, but of course we are looking forward to augmenting Galileo in the near future,” said Sergio Cabrera Bona, EGNOS Service Adoption Tools Engineer at the European Satellite Services Provider, whose core activities comprise EGNOS operations and service provision.
“GNSS is critical in all of these fields, whether it is mapping and GIS, farming, forestry, thermal pictures, management of natural terrains,” Cabrera said. He listed other areas, including management and inspection of utilities, power networks, water supply, telecoms, drones, inventory, surveying, field campaigns and determination of perimeters in agriculture as areas where GNSS plays a key role.
“It is not possible to mention all of the activities where you need reliable positioning. What you have to know is that with EGNOS augmentations you already have a horizontal accuracy below one metre and a vertical accuracy below two metres, so this is a very good accuracy,” he said.
There is much more that could potentially be done right now, Cabrera explained. “Most of the professional equipment is already EGNOS-enabled, but in practice users do not always configure their equipment correctly to exploit this capability. EGNOS adoption and support is going ahead full speed, but in the GNSS device market, many users still do not know they can use EGNOS. So the education process remains an ongoing effort,” he said.
Cabrera explained that the EGNOS user support website can be an important part of this educational drive on the top of the help desk. “We have very interesting tools and resources available online. For example, we will have a new EGNOS usability map available very soon on the website. With this tool you will be able to easily see the current availability of EGNOS signals in your location, which will be very useful especially in urban environments, for example. We also have many user support services and there is a new mobile app coming, so please visit our website and take advantage of EGNOS. It is there for you.”
Introducing the GSC
Galileo services improvement expert Pedro Gómez Martínez informed participants about the European GNSS Service Centre (GSC), defining both the concept of operations as well as the procedures necessary to provide the services that the GSA offers to Galileo users.
“The European GNSS Service Centre is the single interface between the infrastructure and users of the Galileo open services, commercial service and search and rescue service (SAR),” said Gómez. “So the GSC is a center that provides experts, know-how, evaluation of capability, distribution of information and support for the provision of value-added services provided by the Galileo system.”
The GSC website is a core resource for Galileo users, Gómez said, reporting real-time system status and incident notifications, with a bank of key documents and a full-time help desk. “It is very important for us that this is a two-way interactive service that includes your feedback. We need you to report any incidents that you might experience related to the product, service and data provision. We are very interested in user satisfaction, and we want to know how you respond to improvements. And of course, in general, we are here to promote GNSS in all its forms, in all areas, for all users.”
The GSC launched a new version of its website in the run-up to the InterGEO event. “More than ever we are making it easier for you to engage in dialogue with us and to provide your feedback. This is very important to us with new services coming up in the future,” Gomez said.
Research fundamentals
“One of the very important responsibilities of the GSA is the management of a number of EGNSS research and development programmes,” said Eduard Escalona. “We have Horizon 2020, the European Union’s research Framework Programme. There we have a final call for proposals coming up in November, with a deadline in March 2020. The GSA also is overseeing the Fundamental Elements programme, which is funding research specifically targeted at developing Galileo-enabled chipsets, receivers and related technologies.”
To illustrate Escalona’s point, the presentations featured EU-funded GNSS-related research projects leveraging the accuracy and integrity offered by Galileo. Pere Molina of Geonumerics presented the MapKite project. Funded under Horizon 2020 and now completed, MapKite integrates an unmanned aerial system (UAS) and a mobile mapping aystem (MMS) for simultaneous capture of geo-data from the air and from the ground. Molina showed data from a successful corridor mapping exercise run using the MapKite system.
Allystar Technology Co. Ltd., headquartered in Shenzhen, China, is offering new patch antennas: the AGR6302 and AGR6303. Both GNSS antenna models are designed for precision dual-frequency positioning.
AGR6302 is capable of receiving L1/L2 bands, and AGR6303 is capable of receiving L1/L5 bands. They are designed for UAVs, precision agriculture, autonomous vehicles and other applications where precision matters.
The AGR6302/AGR6303 active antenna is designed by unique technology to cover GPS, BDS, Galileo, GLONASS, IRNSS and the QZSS system (see table).
Table: Allystar
The antenna features stable signal quality at low cost. It employs a stack four-feeds antenna architecture with hybrid to achieve the multi-band operation, lower axial ratio, wider half-power beamwidth and excellent right-hand circular polarization, the company said.
Antenna size. (Image: Allystar)
With its new architecture, the active part has two stages. It has two level low noise amplifiers (LNAs) —one for the lower bands, the other for the higher bands. Then, the combiner and the third-level LNA output the RF gain to receiver. With this architecture, the antenna provides an excellent noise figure/RF linear and LNA gain, and out-band rejection, resulting in good signal-to-noise ratio and anti-interference.
It is housed in a compact, industrial-grade waterproof and magnet mount enclosure. Using internal magnets, the antenna can be installed almost anywhere, allowing for greater flexibility.
After many years of development at the fringe of the GNSS industry, dual-frequency GNSS devices are finally ready to hit the mass market and will account for more than a billion chipset shipments in 2023, according to a new market data report by ABI Research.
ABI Research is a market-foresight advisory firm.
The report finds that the bulk of this growth will come from the adoption in the smartphone market with consumers hungry for better location accuracy.
Dual-band GNSS can mitigate the multipath interference effects, which are especially present in areas with a high density of buildings, like urban canyons, and deliver significantly higher accuracy than single-frequency devices.
Broadcom’s BCM47755 chip. (Image: Broadcom)
However, several obstacles prevented widespread adoption of dual-band GNSS until now, including insufficient satellite coverage of a second band, which could be L2 or L5/E5, high chipset prices, and challenges in fitting these integrated circuits and related antennas into small devices such as smartphones.
“On the availability side, this year has seen several satellites launched into orbit every month, most of them fitted with L5/E5 capabilities, and the Chinese and European Union governments plan to have their satellite constellations fully operational by 2020. L5/E5 devices will not be left in the dark,” said Henrique Rocha, a research analyst for Location Technologies at ABI Research.
Furthermore, new breakthroughs from key chipset manufacturers are disrupting this market by overcoming the barriers to mass dual-frequency adoption. With Location-Based Services (LBS) applications in mind, Broadcom has released the BCM47755 dual-band location hub, claiming the system’s architecture achieves the synergistic benefits that cannot be reached by multiple integrated circuits (ICs), thereby reducing its overall size and power consumption.
Other important players in this market have also come forward with dual-frequency solutions, including Qualcomm with the Snapdragon X24 LTE modem and HiSilicon with the Kirin 980 system-on-a-chip. Both attribute their superior energy efficiency and form factor to intelligent data processing and a FinFET transistor design. Other chipset manufacturers such as MediaTek are expected to follow suit and present their own dual-band products for LBS.
The Xiaomi Mi 8. (Photo: Xiaomi)
At the consumer level, considering the handset market is the largest GNSS segment, accounting for 85 percent of all GNSS chipset shipments in 2018, the launch of the dual-frequency Xiaomi Mi 8, Xiaomi Mi Mix 3 and the Huawei Mate 20 following such breakthroughs in the chipset industry is a significant development because it opens a new lane of competition between smartphone manufacturers.
It is expected that dual-frequency devices will dominate the high-end smartphone market in a matter of a few years, and by 2023 dual-band GNSS ICs will comprise 36% of total GNSS LBS IC shipments worldwide.
Triple-frequency chips. In other significant markets for multi-frequency GNSS, such as surveying and automotive applications, triple-frequency chipsets are being released, including STMicroelectronics’ TeseoAPP and u-blox’s F9. Adding a third frequency allows for better noise correction and higher accuracy compared to dual-frequency.
Image: u-blox
ABI Research believes that triple-frequency devices will see, at least for now, a relatively shy adoption as manufacturers will need to justify the cost and overcome the power issues they tackled for dual-frequency devices.
“For LBS the comparatively small accuracy gain going from dual- to triple-frequency GNSS is not worth the extra effort — for now. However, we will probably see triple-frequency GNSS take off when cars fitted with advanced driver assistance and autonomous driving systems begin to ship in large quantities,” added Rocha.
With full satellite operability of the main GNSS bands on the horizon and chipset manufacturers overcoming past hurdles for implementing dual-frequency solutions, it is likely a matter of time before most major companies in the segment scramble for a piece of this promising market. OEMs now need to show customers that dual-frequency GNSS can indeed deliver the accuracy they have promised so new location use cases can be sustained and introduced to the market.
Regular readers of GPS World are aware of many of the rapidly developing technologies and navigational systems being created around the world, but often the everyday surveyor shows up late to the party.
While smartphones get the most mainstream media coverage, other navigational devices and measurement systems are adapting to evolving technical breakthroughs and new methods of transmitting a variety of data wirelessly.
This month’s article looks at the increase in satellite navigation networks along with the rollout of 5G cellular technology. Both advancements will benefit the surveying community; to start, I’ll explain what this means for accuracy and precision of survey measurements as well as productivity.
Everybody gets a constellation! (with apologies to Oprah)
I’ve been known to wax poetic in this column about my admiration of GNSS technology, and I continue to marvel at the “accidental” civilian use of a military tool. This method of measurement and navigation continues to expand, refine and transcend everyday life, and surveying is no exception.
The satellite constellation is the mainstay of this navigational system. The United States began the charge several decades ago, but other nations are quickly catching up. Let’s look at the current constellations and their status.
Operational Systems
GPS (United States)
GLONASS (Russia)
Galileo (European Union)
Beidou (China)
QZSS (Japan)
IRNSS (India)
Chart: GPS World
There are now more satellites. What’s the big deal?
The addition of these constellations provides large gains for the surveying community in several different ways.
First, the additional satellites mean more signals to help with the mathematical equations necessary for positional determination. While traditional surveying in the general public’s eye is associated with measurements on the ground, our expansion of services into the air and water relies heavily on GNSS determined positions.
No matter what type of remote sensing equipment is being used (lidar, photogrammetric, sonar, etc.), positional determination for most of those sensors are derived from GNSS-based receivers. Add to these measuring methods the ability to perform operations via remote-controlled or autonomous vehicles in both air and water, and the availability of additional satellite signals enhances the reliability of GNSS-derived data and attributes.
Second, by having more satellite signals to utilize, GNSS receiver manufacturers can improve the software for processing the positional information with greater certainty of accuracy.
Before the introduction of additional constellations and receivers with expanded signal reception, GNSS users relied on less sophisticated software to identify potential “bad” signals that would lead to incorrect positions. While the software generally provided reasonable reliability, it was not foolproof and occasionally would allow bad data to be accepted.
Like most everything tech-related, however, the GNSS industry has benefited from increased computing power to go along with the additional satellite constellations. The latest GNSS receivers can accept well over 500+ signals from a variety of sources (including land-based transmitters). The software used to reduce all that data has increased in complexity along with number of those data sets.
Complex computations that were once limited to mini-computers or even mainframes are now being completed on handheld data collectors in minuscule timeframes compared to their predecessors.
The software has also been enhanced to analyze the data in real-time, compute the likely position of the receiver and notify the user of potential incorrect or “spoofed” data from any number of satellites.
Considering that many of the remote-sensing sources now collect millions of points based upon one GNSS-based position, the need for increased positional verification has become a critical issue. By having many more constellations to provide signals for positional data, the percentage of establishing a correct location for each data point has increase significantly.
The improved computing power and verification ability of today’s GNSS software is helping to eliminate errors in positional accuracy and instill more confidence in the surveyor’s data collection activities.
Add to these additional constellations the planned installation of more land-based signal providers to augment or provide a backup plan for satellite systems, and it’s clear that the future is quite bright for GNSS-based receivers and data collection for everyone — especially the surveying community.
The history of wireless communication
While surveyors marvel at the advancements of GNSS-based measurement, it pales in comparison to the rapid growth of modern technology with cellular devices. Notice I didn’t write cellular phones, as the technology has quickly established itself as much more than voice communication. Before we lay out the future of cellular data networks, let’s take a step back and see how this type of communication has revolutionized GNSS-derived data collection for surveyors and others.
Two-way, CB and shortwave ham radio
1947 two-way radio advertisement. (Image: Motorola)
The technology behind wireless communication goes back several decades, but didn’t become a mainstream system until the late 1970s and early 1980s. Motorola is known as the early force behind the two-way radio system, but the base and remote transmitters were not cost effective for small businesses. This type of system was also limited to single-purpose radios with individual crystals wired within that only allowed specific frequencies to be transmitted.
Another type of communication used by some was the citizens band radio, affectionately referred to as CB radio. This radio was limited to 40 channels and didn’t allow for private transmission between two parties. During the 1970s, the use of the CB radio was not limited to long-haul truck drivers — many people used the medium for basic communication.
Vintage CB radio ad from Radio Shack. (radioshackcatalogs.com)
Telephone service during these times was still costly and long-distance calls were not cost-effective, so many found the CB radio as an alternative to conventional phone service. Looking back now, it is not a stretch to classify this type of broadcasting as a primitive social media precursor to today’s methods but limited to live chats and no visuals.
Another method of transmission was short-wave radio. This system was like two-way radios with an established base transmitter, but broadcast on public frequencies over greater distances than CB radios. One of the big drawbacks was the upfront costs, which were much more significant than the other radios. Even more expensive was outfitting a vehicle with a shortwave system, so cost was the biggest limiting factor for this mode of communication.
Pagers of all shapes and sizes
Motorola’s Pageboy pager. (Photo: Motorola)
The popularity of telephone-based pagers didn’t hit its zenith until the early 1990s, but the technology and actual use dates to the early 1960s. The first commercial pager was produced by Motorola in 1964 and called the Pageboy. There was no screen or display; the user was notified by a variety of tones preset for distinct situations or needs. As this technology advanced, variations in screens, message types and even two-way communication became possible.
By 1994, there were more than 60 million pagers in use, but a change was in the technological wind; cellular phones were marching toward the mainstream.
While the concept of wireless telephone communication existed in several laboratories around the world for years, the first big breakthrough was made by researcher Martin Cooper, who developed a prototype cellular device for Motorola in the early 1970s. He famously made the first public cellular phone call on April 3, 1973, to Joel Engel, head of research at Bell Labs, during a walk in New York City. Cooper and Engel were engaged in a rivalry to develop the first commercially available cellular phone with the Motorola DynaTAC prototype being the first to make a successful call.
However, the rush to get cellular phones to market took longer than anticipated. It wasn’t until the introduction of the Motorola DynaTAC 8000 in 1983 (available to the public in March 1984) that the reality of wireless phones came to life. The cost of wireless freedom came at a price: $3,500 for a brick-sized phone that took 10 hours to charge for 30 minutes of use. The cost of the service was also expensive due to the limited cellular infrastructure.
The next decade brought us expanded cellular coverage along with miniaturization of phone; each subsequent model provided more features and longer battery life. From the Nokia “candy bar” to the Motorola Razr, the cellphone era had engulfed the mainstream, but more changes were ahead for mobile communications.
The late 1990s saw the introduction of the cellphone as a computer modem, with limited email connectivity and primitive internet browsers built into the operating systems. But like many electronic technologies that came before, the cellphone would begin a radically different life in the mid-2000s.
Enter the smartphone to help us dummies
The IBM Simon Personal Communicator and charging base. (Photo: IBM/public domain)
Officially, the smartphone has been in existence since 1992 with the creation of the Simon Personal Communicator from IBM. At a cost of $1,100, with a monochrome screen that was 4 ½ x 1 ½ inches, the Simon allowed the user access to email and faxes (remember those?) along with the phone function — but users had to make it fast; the battery only lasted an hour. IBM sold 50,000 of these units before pulling the plug on the project, but it started the trend toward mobile telephones with a graphical interface and extended uses beyond the standard verbal communications.
Just like the Apple Newton was the failed precursor to the Palm Pilot, various tablets and eventually today’s smartphone platform, the Simon broke ground and established new directions for future communication.
The early 2000s introduced us to the Blackberry personal digital assistant (PDA) and phones from Research in Motion (RIM), a small electronic communications company from Ontario, Canada. RIM started small with a two-way paging system that became popular in Europe and quickly morphed into cellular devices that worked on the DynaTAC network used by Motorola.
A recent model Blackberry PDA. (Photo: Blackberry)
By the mid 2000s, their devices became affectionately known as the “Crackberry” as users became addicted to the functions and capability of this communication tool. These devices were popular with business users as the security encryption was considered more effective than any of the other communication apparatuses of the day.
By 2009, Blackberry had reached the zenith of the mobile device market (second only to the conventional mobile-phone platform dominated by Nokia) but began a rapid decline due to proliferation of the next big thing — the touchscreen smartphone.
After Apple’s introduction of the iPhone in 2007, followed by a crowd of Android-powered phones in 2008 and beyond, Blackberry’s market share has been reduced to a small niche group.
And now, why this relates to the surveyor…
The rollout of Steve Job’s dream of combining Apple’s industry-defining iPod with mobile phone capability revolutionized not only the way we communicate — it has redefined our everyday environment. Many of the tasks we accomplish every day have been incorporated into a smartphone application, which brings us back to the reason this article is directed at surveyors: the device that hangs on your belt or rests in your pocket is revolutionizing the way today’s surveyors work.
Not that long ago, the only navigational devices available were large, expensive and difficult to use. Now, nearly everyone owns a device with GNSS capability. When we combine the ever-expanding number of devices along with the increased coverage of GNSS satellite constellations, the ability to georeference any piece of data to greater precision and accuracy is improving.
Surveyors need to embrace this technology within their smartphones to increase their efficiencies. At the same time, we need to help educate the public on why having better smartphone location capability doesn’t mean the masses can perform their own boundary analyses. For more information on this subject, see the GPS World July 2017 article.
Surveyors should embrace the smartphone as an important tool; the introduction of new survey-grade GNSS receivers that use an app for the user interface will soon become commonplace.
Several GNSS manufacturers have introduced receivers that exclusively use a smartphone and app for data collection, eliminating the need for a dedicated (and usually proprietary) data collector for obtaining centimeter-level location data. I’m not advocating that the surveying community throw their existing systems in the trash in favor of these newer receivers, but the data-collection techniques utilized by smartphones can increase efficiency and reduce equipment costs.
The Mi 8 smartphone offers dual-frequency capability. (Image: Xiaomi)
Another reason to pay attention to the smartphone as a location tool will be the expanded use of dual-frequency chipsets to provide even higher accuracies. One of the fastest growing phone makers worldwide is Xiaomi, based in Beijing, China, which introduced the Mi 8 phone with a dual-frequency GNSS chip. This chip frequency reception (E1/L1+E5/L5) is targeted to embrace the Galileo and GPS constellations for increased accuracies (within a decimeter), well beyond the current norm for smartphones (typically 1-3 meters, plus or minus). For the surveyor, having this capability in their pocket can greatly increase efficiencies, especially when used during reconnaissance efforts. I believe many more phone manufacturers will begin to incorporate dual-frequency chips in their future models to increase location accuracies for users and take advantage of upcoming network enhancements.
Speaking of network enhancements, let’s talk 5G as a gamechanger.
The latest buzz in the general population’s lexicon is 5G and how it will push high-speed internet to all corners of the world. While this is a possibility, it means much more to the surveyor than meets the eye. Yes, there will be increased cellular coverage in places that previously lacked it, or only had limited access, but 5G means much more than that.
Image: NTT DOCOMO Inc. 5G white paper.
Let’s refresh our view of what cellphone coverage currently means to the surveyor. The use of cellular-based RTK receivers has been greatly expanded due to the increased coverage of 4G LTE signals throughout the world, but it’s still scarce is some parts. This is mostly due to the transmission of cellular signals being required from towers and higher placed antennas with powerful transmitters. These transmitters are costly and typically owned and installed by the larger telecom companies, so placement is traditionally in more populated areas.
Enter 5G — while it will provide enhancements for all users, it will be revolutionary for the surveyor. 4G cell coverage was a broad and powerful signal from large transmitters; 5G cellular service consists of smaller cell signals placed in a tight grid of broadcast positions. These transmitters will be more cost effective for many telecom providers and will increase data reception for many users. For surveyors, the additional coverage of 5G will make possible the use of cellular-based RTK GNSS data collection in places not previously possible.
Besides the extended coverage of 5G, the 10-fold speed of the new data transmission protocol compared old 4G LTE creates many possibilities for information collection growth. Soon it will be possible for a field personnel and the office staff to be linked in real time during the data collection process.
From boundary-point recovery to complex topographic surveys, a field crew’s work can be supervised and reviewed while being completed, allowing for instantaneous analysis and guidance from senior staff. This process will allow for more oversight, quality control and mentoring of field staff than is possible for today’s remote crew operations. The new technology will also allow for reduced timeframes when crews are required to provide field data for tight deadline requests and gives us a method of instant feedback on the amount and quality of the data collection.
Some may see this improvement in connectivity as an avenue for office staff to be intrusive on their field activities, but I see this as an opportunity for improved quality control and increased team interaction. More connected teams can lead to improved efficiencies and overall increases in productivity, profitability and morale among team members.
From outside to inside
Another breakthrough created by 5G will be the enhancement of indoor georeferenced location services. By having several transmitters placed throughout a facility, trilateration will be possible to provide more accurate location information for places not typically available to surveyors.
Depending on the accuracy needed and placement of the cell providers, it will possible for surveyors to use devices designed for remote sensing (laser scanners, lidar, SLAM, etc.) and collect georeferenced data with greater accuracy in relation to a known coordinate system. This by-product will also aid rescue and medical providers during emergencies to help pinpoint individuals through their cellphone connection more accurately than before.
5G is more than just bringing YouTube videos to your phone faster; it will improve the data collection process of all shapes and sizes. Surveyors will not get left out, but we will need to be ready to take advantage when it comes online. For more on the 5G revolution, see the GPS World February 2018 article on this topic.
As surveyors, just when we think that technology can’t take us further, we blink and change happens. Moore’s law stated (depending on which revision) that technology would double the number of transistors every one to two years. While some may say that technology is making Moore’s law obsolete, I believe the creativity being used to invent new processes based upon the technology is holding strong.
I, for one, look forward to many more enhancements to follow in the coming years. Surveyors be ready; the future is here.
By Paolo Crosta, Paolo Zoccarato, Rafael Lucas and Gerarda De Pasquale, European Space Agency
Test set-up. (Image: Authors)
Most mass-market manufacturers have already developed a dual-frequency chip or will soon do so. What is still not completely clear is the main benefit of adding the second frequency. Is it beneficial just for correcting ionospheric error?
Will it provide an improvement of the ranging error thanks to the wideband nature of the signal broadcast on the second frequency and their multipath rejection capabilities? Is it improving the measurement quality by means of a higher transmitting power?
Could it be exploited as a source of data for the provision of accurate orbit and clock corrections? What is the best PVT algorithm to apply to a multi-constellation dual-frequency mass-market chip?
To answer these questions, an evaluation kit of the Broadcom chip BCM4775 has been tested — the first dual-frequency mass-market chip commercially available.
Results show:
the code noise (multipath) is often the main source of error, hiding the benefits of more accurate clocks and orbital data.
wide-band signals are very beneficial for multipath rejection. Position fix based on E5a-L5-only measurements even with fewer satellites can outperform L1-E1-only in tests performed this September (impact of the new Galileo satellites).
after deactivation of the duty-cycle tracking on Android phones, the carrier phase measurements are improved and we do not experience any longer filter resets in the position Kalman filter.
GNSS antenna maker Tallysman has introduced the TW7875 magnetic mount GNSS antenna, which is designed for precision dual-frequency positioning. It is capable of receiving GPS L1/L5, GLONASS G1, BeiDou B1, Galileo E1/E5a and NavIC L5.
The TW7875 employs Tallysman’s Accutenna technology, which provides superior multipath signal rejection due to its low axial ratio across the full bandwidth, the company said.
The antenna also provides a linear phase response and tight phase center variation at a new economical price point, according to the company, which said it provides performance comparable to higher priced dual-band GNSS antenna.
It is designed for precision agriculture, autonomous vehicles and other applications where precision matters.
The TW7875 is housed in a magnetic mount IP67 rated housing. It can also be ordered without the magnet since it can also be mounted by screws or double-sided adhesive tape.
Model TW3875 is the embedded antenna version of the TW7875. It is available with a wide selection of connectors and custom cable lengths, and can be custom tuned by Tallysman to ensure optimum performance within the customer’s enclosure.
Mobile brand Xiaomi has launched a dual-frequency GNSS smartphone.
Fitted with a Broadcom BCM47755 chip, the Xiaomi Mi 8 provides up to decimeter-level accuracy for location-based services and vehicle navigation, the company said.
The Mi 8 smartphone represents a breakthrough in GNSS technology as the first commercial deployment of Broadcom’s dual-frequency BCM47755 chip designed for the mass market and introduced in September 2017.
Until now, mobile location-based applications have been powered by single-frequency GNSS receivers whose location accuracy is limited to a few meters. However, in recent years GNSS systems have been launching satellites broadcasting signals on new frequencies to open up new possibilities. Specifically, Galileo has the majority of satellites with E1/L1 and E5/L5 frequency capabilities.
The E1/L1 + E5/L5 GNSS chip can compute location with an accuracy of up to a few decimeters.
Leveraging Galileo for increased accuracy
According to the company, users of the Xiaomi Mi 8 and future models with dual-frequency GNSS will benefit from better positioning and navigation experience in urban environments. This is due to the unique shape of the E5/L5 frequency, which makes it easier to distinguish real signals from the ones reflected by buildings, reducing the multipath effect, a major source of navigation error in cities and other challenging environments.
The numerous Galileo satellites broadcasting E5 make this improvement available for users all around the world. In addition, the simultaneous use of two frequencies reduces other sources of error, such as those due to the ionosphere, and the frequency diversity is more robust to interference and jamming.
In addition to making existing applications more accurate, the enhanced position precision offered by dual-frequency GNSS will also create opportunities for new applications in areas such as augmented reality, vehicle navigation and mapping.
Commenting on the product launch, European GNSS Agency (GSA) head of market development Gian Gherardo Calini said that the arrival of the first dual-frequency GNSS smartphone to the mass-market represents a breakthrough for users all over the world.
“The enhanced accuracy provided will empower developers to create new applications that meet the growing high-accuracy location requirements of users and also open up applications that previously only ran in dedicated devices intended for professional use,” Calini said.
“Broadcom is glad to gear up Xiaomi’s flagship smartphones with the very latest dual-frequency GNSS technology,” added Alex Chou, vice president of product marketing for the Wireless Communications and Connectivity Division at Broadcom. “Xiaomi Mi 8, the world’s first smartphone with BCM47755, will take smartphone GNSS navigation to a whole new performance level.”
”The importance of GNSS to modern life is undisputed, and is particularly important for smartphones,” said Zhiyuan Zang, Xiaomi’s director of product marketing. “Navigation and LBS-based apps these days require greater positioning accuracy to work effectively, and dual-frequency GNSS is the key to delivering a great user experience when using these apps. Xiaomi is delighted and honored to be the world’s first smartphone manufacturer to support dual-frequency GNSS. We will continue to pursue innovation for everyone to enjoy.”
Access to raw measurements for geolocation
The launch of the first dual-frequency GNSS smartphone, together with the opportunities offered by the availability of GNSS raw measurements in Android, creates exciting opportunities for the geolocation community, the company said.
Access to raw measurements opens the door to algorithms once restricted to more advanced GNSS receivers. This, in turn, allows users to fully benefit from the differentiators offered by Galileo.
Recognizing these opportunities, in 2017 the GSA engaged with academia and industry in the areas of navigation and positioning to innovate around this new feature as part of a GNSS Raw Measurements Task Force.
Then, in January, the GSA published a white paper on the use of GNSS Raw Measurements in Android, providing developers with in-depth information on accessing and using raw measurements to implement advanced GNSS techniques in mass-market devices.
Building on this work, the GSA and the Raw Measurements Taskforce shared their latest updates at a dedicated workshop — “GNSS Raw Measurements: From Research to Commercial Use” — held at the GSA headquarters in Prague on May 30, where Broadcom presented its encouraging test results from the dual-frequency BCM47755.
By Paul Verhoef
Director of the Galileo Programme and Navigation-related Activities,
European Space Agency
Paul Verhoef, director of the Galileo Programme. (Photo: ESA)
The European Space Agency (ESA) and the European GNSS Agency (GSA) are starting 2018 with the commissioning and In-Orbit Testing (IOT) of four new Galileo satellites.
This work is fairly routine for us as we have achieved the process successfully many times. But the impact of four new satellites for Galileo services is a different story.
This batch of satellites provided by OHB of Germany — 19, 20, 21 and 22 — will bring our constellation to 22 satellites. Together with the necessary ground segment delivered by Thales Alenia Space (TAS) and Airbus Defense and Space (ADS) and their many subcontractors throughout Europe, this will be providing availability to users anywhere in the world in order to achieve a high-quality position solution 99.8% of the time. “High quality” is hereby meant that the position dilution of precision (PDOP) will be smaller than 5, with our final accuracy for a full 24 FOC satellites operating at full potential being PDOP ~ 2.4.
This achievement will create a step change in the ability of service providers and equipment manufacturers to utilize the Galileo service. For all intents and purposes, it means the Galileo signal can always be relied upon to be there, and industry can sell products and design the power budget of devices based upon that fact.
Dual Frequency. The first mass-market GNSS receiver chip for smartphones and mobile devices that is able to utilize dual-frequency Galileo signals was released by Broadcom in September, able to employ both L1/E1 and L5/E5 signals. In 2018, dual-frequency technology like this will provide an order of magnitude increase in the performance of mobile device location-based services (LBS), especially in urban environments, and Broadcom advertises a 50% reduction in power consumption. The world of mobile-device LBS is going to change in 2018, and it will be due to the availability of Galileo.
It will not be the first time the partnership of ESA, the European Commission (EC) and the GSA has made a service available that has changed the nature of the marketplace. The GSA already has in service the ESA-designed EGNOS LPV200 aircraft approach service performing so well that countries like France have taken the decision to phase out the terrestrial Instrument Landing System that has burdened the capital expenditure budgets of airports in the past.
We have had discussions with several commercial organizations that are interested in building products around Galileo, and I am excited to see what they are going to come up with. With Galileo Initial Services the world had a new navigation signal to study and trial. In 2018 the world will have a new star to navigate by — well, a new constellation of 22 to 24 stars, I should say!
FOC. In the summer of 2018 we will launch the final part of the Galileo FOC constellation (geometrically speaking) with four more satellites taking us beyond the 24 needed for 100% coverage and minimum performance limitation from satellite geometry. The launch will also provide our first in-orbit spares, enabling us to plan for the end of life of our old validation phase satellites or otherwise supplement the constellation to improve performance.
What might we do with these in-orbit spares? Our first priority is to complete a constellation of 24 satellites in the correct orbits for minimum PDOP; as you know, a Fregat upper-stage malfunction left GSAT 0201 and 0202 in orbits too elliptical to correct fully, so the current plan is to complete the 24-satellite geometry. 0201 and 0202 are foreseen to be fully integrated in the Galileo operational system in 2018 following further testing and preparations, allowing us to have a 24+2 constellation with “hot back-up” from 0201 and 0202 contributing at around current GPS satellite levels of accuracy.
“It will not be the first — nor the last — time the partnership of ESA, the EC and the GSA has made a service available that has changed the nature of the marketplace.”
Of course, as is known to the community, the validation-phase satellite GSAT 0104 is down to single frequency, and we routinely monitor the health of all satellites. 0104 is the only satellite that has lost part of its function; designed-in redundancy has managed all other problems.
However, obviously we will be examining all options for deployment to ensure that the Galileo schedule is not impacted by in-orbit failures, and those we have experienced we have learned from and mitigated successfully without impacting the service.
The first two spares are not the end of our ability to maintain the constellation and our system performance. All four validation phase satellites will need to be replaced, and so the “Batch 3” satellite procurement will continue to regularly roll out satellites for replenishment of the constellation.
Enhancements. That won’t mean we will be resting on our laurels. In 2018 we also plan to release enhancements to the ground segment for Galileo, a process that will be a first as the system is already being operated by the GSA.
The process of managing an in-service upgrade program with the GSA is going to be new and challenging, but we have a strong engineering support team deployed as part of our working arrangement with the GSA to help ensure the process goes smoothly.
Of course, the need for GSA to be able to continue smooth operations imposes extra discipline and imposes on us a balance between stable operations and continued build-out of the infrastructure. We do not consider this to be a problem; on the contrary, the focus will be on robust operations and availability to the user.
Back at base (ESTEC in the Netherlands for Galileo and Toulouse, France, for EGNOS) we are full steam ahead on preparing the future. We are moving forward at considerable pace with our next-generation designs that develop new functionality for continuous service improvements.
Free PPP. Galileo was designed to broadcast a Commercial Service signal providing services such as precise point positioning to paying customers, but we are pleased to able to report that the EC has confirmed that this service will be provided for free by the European Union. In 2018/2019 the GSA will select the providers and get that unique, free service on the air.
In 2017 the EC confirmed the decision to implement the commercial service using E6-B with both encrypted and open components so all users could benefit for all frequency bands. Now, with the decision to make the service available free of charge, all users of Galileo, with the right type of receiver, will be able to achieve position fixes with an accuracy around 10 cm from Galileo’s first-generation constellation by 2020/2021.
The Galileo Public Regulated Service will also be a focus, with the EC soon to decide upon release dates for the first milestones on the service roadmap. The infrastructure and equipment to support a secure service is being put in place, and I can’t say more for security!
The next generation of European GNSS technology will include multi-constellation EGNOS, Galileo 2nd Generation (G2G) and a transition batch of satellites between the first and second generations to get the best technology proven in flight and working for Galileo users as soon as possible. G2G will reach its System Requirements Review stage in the first half of 2019. To be ready for that we are looking at:
clock technology and ensembles
inter satellite links
propulsion technology
flexible payloads and power allocation
5G telecoms networks standards and what we need to do ensure we provide the timing services those networks will need and new signals with time to first fix (TTFF) and power requirements for acquisition of signal that are compatible with 5G devices. Look out for a new pilot signal E1-D to move forward on this.
Open Service authentication and support for ARAIM (Advanced Receiver Autonomous Integrity Monitoring).
Finally, 2018 will see the first contract awards of the Navigation Innovation Support Programme. This is a programme specifically designed to encourage R&D, new concepts and new products and to ensure that 2018 is not the last time ESA with the EC and its industrial partners deploy a GNSS service for GSA to operate that changes the world.
Tallysman, a manufacturer of high-performance GNSS antennas, has launched a higher gain dual-frequency embedded antenna: the TW3870E. The TW3870E antenna has a typical gain of 35 dB which is required by some GNSS receivers, such as Trimble’s BD9xx family of receivers.
The antenna is capable of receiving GPS L1/L2 and GLONASS G1/G2 signals. It employs Tallysman’s Accutenna technology, which can provide low axial ratios, high multi-path signal rejection, low noise, tight PCV and a phase linear response.
The TW3870E is 60 mm in diameter and has four drilled plated holes for secure mounting within customers’ products. The antenna can be custom tuned to ensure optimal performance. Custom cable lengths and connectors are also available.
The antenna is REACH and ROHS compliant.
Visit Tallysman’s booth at INTERGEO 2015, Hall E8, Booth 038 to learn more about the TW3870E and other Tallysman antennas.
Hyman Huang of South Surveying & Mapping Instrument Co. talks with GPS World about the company’s new dual-frequency GNSS Receiver and its tablet counterpart while at InterGeo 2014, held October 7-9 in Berlin.
The implementation changes and first live tests of BeiDou and Galileo on Teseo-3 GNSS chips developed in 2013 are covered, bringing it to a four-constellation machine. By 2020, we expect to have four global constellations all on the same band, giving us more than 100 satellites — under clear sky, as many as 30 or 40 simultaneously.
By Philip G. Mattos and Fabio Pisoni
Multi-constellation GNSS first became widely available in 2010/2011, but only as two constellations, GPS+GLONASS. Although receivers at that time may have supported Galileo, there were no usable satellites. BeiDou was a name only, as without a spec (an interface control document, or ICD), no receivers could be built. However, the hardware development time of receivers had been effectively shortened: the Galileo ICD had been available for years, BeiDou codes had been reverse-engineered by Grace Gao and colleagues at Stanford, and at the end of 2011 they were confirmed by the so-called test ICD, which allowed signal testing without yet releasing message characteristics or content.
The last weeks of 2012 saw two great leaps forward for GNSS. Galileo IOV3 and 4 started transmitting at the beginning of December, bringing the constellation to four and making positioning possible for about two hours a day. At the end of December, the Chinese issued the BeiDou ICD, allowing the final steps of message decode and ephemeris calculation to be added to systems that had been tracking BeiDou for many months, and thus supporting positioning. The Teseo-2 receiver from STMicroelectronics has been available for some years, so apart from software development, it was just waiting for Galileo satellites; however, for BeiDou it needed hardware support in the form of an additional RF front end. Additionally, while it could support all four constellations, it could not support BeiDou and GPS/Galileo at the same time, as without the BeiDou ICD the spreading codes had to be software-generated and used from a memory-based code generator, thus blocking the GPS/Galileo part of the machine.
The Teseo-3 receiver appeared late in 2013, returning to the optimum single-chip form factor: RF integrated with digital silicon and flash memory in the same package, enabling simultaneous use of BeiDou and GPS/Galileo signals. Multi-constellation in 2012 was GPS+GLONASS, which brought huge benefits in urban canyons with up to 20 visible satellites in an open sky. Now, for two hours a day in Europe while the Galileo IOVs are visible, we can run three constellations, and in the China region, GPS/BeiDou/Galileo is the preferred choice.
This article covers the first tracking of four Galileo satellites on December 4, 2012, first positioning with Galileo, and first positioning with BeiDou in January 2013. It will cover static and road tests of each constellation individually and together as a single positioning solution. Road tests in the United States/Europe will combine GPS/GLONASS/Galileo, while tests in the China region will combine GPS/Galileo/BeiDou. Results will be discussed from a technical point of view, while the market future of multi-constellation hardware will also be considered.
In the 2010–2020 timeframe, GLONASS and BeiDou (1602 MHz FDMA and 1561 MHz respectively) cost extra silicon in both RF and digital hardware, and cause marginal extra jamming vulnerability due to the 50 MHz bandwidth of the front end. The extra silicon also causes extra power consumption.
After 2020, GLONASS is expected to have the L1OC signal operational, CDMA on the GPS/Galileo frequency, and BeiDou is expected both to have expanded worldwide, and also to have the B3 signal fully operational, again on 1575 MHz. At that point we will have four global constellations all on the same band, giving us more than 100 satellites. With a clear sky, the user might expect to see more than 30, sometimes 40, satellites simultaneously.
Besides the performance benefits in terms of urban canyon availability and accuracy, this allows the receiver to be greatly simplified. While code generators will require great flexibility to generate any of the code families at will, the actual signal path will be greatly simplified: just one path in both RF (analog) and baseband (digital) processing, including all the notch filters, derotation, and so on. And this will greatly reduce the power consumption.
Will the market want to take the benefit in power consumption and silicon area, or will it prefer to reuse those resources by becoming dual-frequency, adding also the lower-L-band signals, initially L5/E5, but possibly also L2/L3/L6 ? The current view is that the consumer receiver will go no further than L5/E5, but that the hooks will be built-in to allow the same silicon to be used in professional receivers also, or in L2C implementations to take advantage of the earlier availability of a full constellation of GPS-L2C rather than GPS-L5.
This article presents both technical results of field trials of the quad-constellation receiver, and also the forward looking view of how receivers will grow through multi-frequency and shrink through the growing signal commonalities over this decade.
History
Galileo was put into the ST GPS/GNSS receiver hardware from 2006 to 2008, with a new RF and an FPGA-based baseband under the EU-funded GR-PosTer project. While a production baseband (Cartesio-plus) followed in high volume from 2009, in real life it was still plain GPS due to the absence of Galileo satellites.
The changed characteristics in Galileo that drove hardware upgrades are shown in Figure 1. The binary offset carrier BOC(1,1) modulation stretches the bandwidth, affecting the RF, while both the BOC and the memory codes affect the baseband silicon in the code-generator area.
Figure 1. Changes for Galileo.
Next was the return to strength of the GLONASS constellation, meaning receivers were actually needed before Galileo. However the different center frequency (1602 MHz), and the multi-channel nature of the FDMA meant more major changes to the hardware. As shown in Figure 2 in orange, a second mixer was added, with second IF path and A/D converter.
Figure 2. Teseo-2 RF hardware changes for GLONASS.Figure 3. Teseo-2 and Teseo-3 baseband changes for GLONASS.
The baseband changes added a second pre-processing chain and configured all the acquisition channels and tracking channels to flexibly select either input chain. Less visible, the code-generators were modified to support 511 chip codes and 511kchips/sec rates.
Teseo-2 appeared with GPS/GLONASS support in 2010, and demonstrated the benefit of GNSS in urban canyons, as shown by the dilution of precision (DOP) plot for central London in Figure 4. The GPS-only receiver (in red) has frequent DOP excursions beyond limits, resulting either in bad accuracy or even interrupted fix availability. In contrast, the GNSS version (in blue) has a DOP generally below 1, with a single maximum of 1.4, and thus 100 percent availability. Tracking 16 satellites, even if many are via non-line-of-sight (NLOS) reflected paths, allows sophisticated elimination of distorted measurements but still continuous, and hence accurate, positioning.
Figure 4. DOP/accuracy benefits of GNSS.
BeiDou
Like Galileo, BeiDou is a story of chapters. Chapter 1 was no ICD, and running on a demo dual-RF architecture as per the schematic shown in Figure 5. Chapter 2 was the same hardware with the test ICD, so all satellites, but still no positioning. Chapter 3 was the full ICD giving positioning in January 2013 (Figure 6), then running on the real Teseo-3 silicon in September 2013, shown in Figure 7.
Figure 5. Demo Teseo-2 dual RF implementation of BeiDou.Figure 6. Beidou positioning results.Figure 7. Teseo 3 development board.
The Teseo-3 has an on-chip RF section capable of GPS, Galileo, GLONASS and BeiDou, so no external RF is needed.
The clear green space around the Teseo-3 chip in the photo and the four mounting holes are for the bolt-down socket used to hold chips during testing, while the chip shown is soldered directly to the board. Figure 8A shows the development board tracking eight BeiDou satellites visible from Taiwan.
However, the silicon is not designed to be single-constellation; it is designed to use all the satellites in the sky. Figure 8b shows another test using GPS and BeiDou satellites simultaneously.
Figure 8A. Beidou.Figure 8b. GPS+Beidou.
A mobile demo on the Teseo-3 model is shown running GPS plus BeiDou in Figure 9, a road test in Taipei. Satellites (SV) up to 32 are GPS, those over 140 are BeiDou, in the status window shown: total 13 satellites in a high-rise city area, though many are non-LOS.
Figure 9. GPS + Beidou roadtrack in Taipei.
Extending the hardware to add BeiDou, which is on 1561 MHz and thus a third center frequency, meant adding another path through the IF stages of the on-chip radio. After the first mixer, GPS is at 4 MHz, and GLONASS at about 30 MHz, but BeiDou is at minus 10 MHz. While the IF strip in general is real, rather than complex (IQ), the output of the mixer and input to the first filter stage is complex, and thus can discriminate between positive frequencies (from the upper sideband) and negative ones (from the lower sideband), and this is normally used to give good image rejection. In the case of BeiDou, the filter input is modified to take the lower sideband, that is, negative frequencies, and a second mixer is not required; the IF filter is tuned to 10 MHz. The new blocks for BeiDou are shown in green in Figure 10. The baseband has no new blocks, but the code generator has been modified to generate the BeiDou codes (and, in fact, made flexible to generate many other code types and lengths). Two forms of Teseo-3 baseband are envisaged, the first being for low-cost, low-current continues to have two input paths, so must choose between GLONASS and BeiDou as required. A future high-end model may have an extra input processing path to allow use of BeiDou and GLONASS simultaneously.
Figure 10. Teseo-3 RF changes for Beidou shown in green.
Galileo Again
Maintaining the chronological sequence, Galileo gets a second chapter in three steps. In December 2012, it was possible for the first time to track four IOV satellites simultaneously, though not to position due to the absence of valid orbit data. In March 2012, it was possible for the first time to demonstrate live positioning, and this was done using Teseo-2 simultaneously by ESA at ESTEC and STMicro in Naples and Milan, our software development centres.
The demos were repeated in public for the press on July 24, 2013, at Fucino, Italy’s satellite earth station, with ESA/EC using the test user receiver (TUR) from Septentrio, and ST running simultaneous tests at its Italian labs. Figure 11 and Figure 12 show the position results for the data and pilot channels respectively, with independent LMS fixes. In real life, the fixes would be from a Kalman filter, and would be from a combined E1-B/E1-C channel, to take advantage of the better tracking on the pilot.
Good accuracy is not expected from Galileo at this stage. The four satellites, while orbited to give good common visibility, do not also give a good DOP; the full set of ground monitoring stations is not yet implemented and cannot be well calibrated with such a small constellation. Finally, the ionospheric correction data is not yet available. Despite these problems, the residuals on the solutions, against a known fixed position for the rooftop antenna, are very respectable, shown in Figure 13.
Figure 13. Galileo residuals, L1-B.
The common mode value is unimportant, representing only an offset in the receiver clock, and 10 meters is about 30 nanoseconds. The accuracy indicator is the spread between satellites, which is very respectable for a code-only receiver without full iono correction, especially around 640 on the TOW scale, where it is less than 2 meters. The rapid and major variation on the green data around t=400 is considered to be multipath, as the roof antenna is not ideally positioned with respect to other machinery and equipment also installed on the roof.
QZSS and GPS-III/L1C
Teseo-2 has supported the legacy (C/A code) signal on QZSS for some time, but Teseo-3 has been upgraded to handle the GPS-III/L1-C signal, waiting for modernized GPS. This signal is already available on the QZSS satellite, allowing tests with real signals. Significant changes were required in the baseband hardware, as the spreading code is a Weill code, whose generation complexity is such that it is generated once when the satellite is selected, then replayed real time from memory. Additionally it is long, in two domains. It is 10230 chips — that is, long to store but also long in time, with a 10-millisecond epoch. On Teseo-3, the legacy C/A code is used to determine code-phase and frequency before handing over to the Weill code for tracking.
Using a long-range crystal ball and looking far into the future, a model of the future Teseo-4 DSP hardware is available, with 64 correlation taps per satellite. Running this on the captured QZSS L1-C signal gives the correlation response shown in Figure 14. Having multiple taps removes all ambiguity from the BOC signal, simultaneously removing data transitions, which can alternatively be pre-stripped using the known pilot secondary code (which on GPS III is 5 dB stronger than the data signal). The resultant plot represents 2,000 epochs, each of 10 milliseconds, plotted in blue, with integrated result for the full 20 seconds shown in the black dashed line. Assuming vehicle dynamics is taken out using carrier Doppler, this allows extremely precise measurement of the code phase, or analysis of any multipath in order to remove it. This RF data was captured on a benign site with a static antenna, so it shows little distortion.
Figure 14. L1-C tracking on QZSS satellite.Figure 15. Dual RF implementation of dual-band front end.
The Future
Having already built in extreme flexibility to the code generators to support all known signals and generalized likely future ones, the main step for the future is to support multiple frequencies, starting with adding L5 and/or L2, but as before, ensuring that enough flexibility is built in to allow any rational user/customer choice. It is not viable for us to make silicon for low-volume combinations, nor to divide the overall market over different chips. Thus our mainstream chip must also support the lower volume options.
We cannot, however, impose silicon area or power consumption penalties on the high-volume customer, or he will not buy our product.
Thus, our solution to multi-frequency is to make an RF that can support either band switchably, with the high band integrated on the volume single-chip GNSS. Customers who also need the low band can then add a second RF of identical design externally, connected to the expansion port on the baseband, which has always existed for diagnostic purposes, and was how BeiDou was demonstrated on T2. By being an RF of identical design to the internal one, it incurs no extra design effort, and would probably be produced anyway as a test chip during the development of the integrated single-chip version. Without this approach, the low volume of sales of a dual-band radio, or a low-band radio, would never repay its development costs.
Conclusions
All four constellations have been demonstrated with live satellite signals on Teseo-2, a high-volume production chip for several years, and on Teseo-3 including use in combinations as a single multi-constellation positioning solution. With the advent of Teseo-3, with optimized BeiDou processing and hardware support for GPS-3/L1C, a long-term single-chip solution is offered.
For the future, dual-frequency solutions are in the pipeline, allowing full advantage of carrier phase, and research into moving precise point positioning and real-time kinematic into the automotive market for fields such as advanced driver-assistance systems.
Acknowledgments
Teseo III design and development is supported by the European Commission HIMALAYA FP-7 project.
This article is based on a technical paper first presented at ION-GNSS+ 2013 in Nashville, Tennessee.
ST GPS products, chipsets and software, baseband and RF are developed by a distributed team in: Bristol, UK (system R&D, software R&D; Milan, Italy (Silicon implementation, algorithm modelling and verification); Naples, Italy (software implementation and validation); Catania, Sicily, Italy (Galileo software, RF design and production); Noida, India (verification and FPGA). The contribution of all these teams is gratefully acknowledged.
Philip G. Mattos received an external Ph.D. on his GPS work from Bristol University. Since 1989 he has worked exclusively on GNSS implementations, RF, baseband and applications. He is consulting on the next-generation GNSS chips, including one-chip GPS (RF+digital), and high-sensitivity GPS and Galileo for indoor applications, and combined GPS/Galileo/GLONASS chipsets. In 2008-2009, he re-implemented LORAN on the GPS CPU, and in 2009-2010 led the GLONASS implementation team. He is leading the team on L1C and BeiDou implementation, and the creation of totally generic hardware that can handle even future unknown systems.
Fabio Pisoni has been with the GNSS System Team at STMicroelectronics since 2009. He received a master’s degree in electronics from Politecnico di Milano, Italy, in 1994. He was previously with the GNSS DSP and System Team in Nemerix SA and has earlier working experience in communications (multi-carrier receivers).
TW3802 Shown with flat radome. Conical radome also available.
Tallysman Wireless Inc. has added the dual-frequency TW3800 series to its high-quality precision line of antenna products.
The TW3800 series antennas feature a circular stacked patch antenna for improved axial ratio, yet are small and light, and have the extended bandwidth required for L1/L2 GPS & G1/G2 GLONASS, the company said. The operating voltage range is from +2.5 to 16 VDC. The antennas have a temperature compensated LNAs and operate from -40 to +85o C to provide reliable performance in most any environment. The TW3800 is packaged in a through hole mount making it suitable for mobile applications.
The TW380x is suited for many applications, including:
Anti-jamming GPS
Mission-critical GPS timing
Military and security
Network timing and synchronization
Precise tracking
High signal availability
The TW3805 is the OEM version of the TW3802, and can be custom tuned to provide optimal performance inside virtually any housing, Tallysman said.
“The circular patch design of the TW380X antennas permits precision custom tuning with excellent axial ratios.” said Gyles Panther, president of Tallysman Wireless. “This flexibility, combined with the very wide operating voltage enables this antenna to work with virtually any receiver on the market.”
