Global Navigation Satellite System (GNSS) technology has been instrumental in revolutionizing our world, with applications from navigation and mapping to precise timing and synchronization fundamentally changing over the last 50 years. Here we are going to delve into the future of GNSS technology, focusing specifically on the new signals being released in the GPS, GLONASS, Galileo, and BeiDou satellite systems and what this means for you. We will explore the potential differences these advancements will make for surveyors using Real-Time Kinematic (RTK) equipment.
A modern 7th generation receiver being used in the survey of a water tributary. With the latest GNSS signals, RTK equipment is becoming more and more accessible.
Impact on Surveyors Using RTK Equipment
Case Studies and Practical Applications
Future Prospects and Challenges
Overview of GNSS Technology
Global Navigation Satellite System (GNSS) technology encompasses a range of satellite-based systems that provide geolocation and time information to a GNSS receiver anywhere on or near the Earth’s surface. The primary GNSS systems include the United States’ Global Positioning System (GPS), Russia’s GLONASS, the European Union’s Galileo, and China’s BeiDou. These systems have been pivotal in various applications, including navigation, mapping, scientific research, and timing.
Importance of RTK in Surveying
Real-Time Kinematic (RTK) positioning is a technique used in surveying and geodesy to achieve centimeter-level accuracy. RTK works by using a fixed base station and a mobile rover station. The base station transmits correction data to the rover, allowing it to correct its position in real-time. This high level of precision is crucial for applications requiring exact measurements, such as construction, agriculture, and land surveying. However, RTK is sensitive to signal quality and availability and the advancements in GNSS signals over the last several decades have completely changed where this technology can be deployed and the reliability of these signals.
The development of GNSS signals has evolved significantly since the inception of GPS in the 1970s. Initially designed for military applications, GPS was later opened for civilian use. Originally, there were no plans to allow civilians to use GPS, but this all changed with the shootdown of Korean Air Lines Flight 007 due to an accidental navigation error.
The initial signals, such as GPS L1 C/A, were limited in accuracy and susceptibility to errors like ionospheric delay and multipath interference. Over the decades, advancements in signal technology have aimed to overcome these limitations, providing higher accuracy, better reliability, and improved integrity. Originally, without long occupation times, civilian GNSS receivers were capable of resolving the position to several hundred meters.
GNSS technology has become ubiquitous in our world. From surveying to your cell phone, nearly all of today’s modern technology relies on GNSS in one way or another.
Current GNSS Signals
Today, GNSS systems use a variety of signals to enhance positioning accuracy and reliability. For instance, GPS uses L1, L2, and L5 frequencies; GLONASS utilizes L1, L2, and L3; Galileo offers E1, E5, and E6 signals; and BeiDou provides B1, B2, and B3 frequencies. These signals differ in frequency, modulation, and error correction capabilities, contributing to the overall performance of GNSS technology.
GPS (Global Positioning System)
L1C Signal
The L1C signal is a recent addition to the GPS constellation, designed to enhance compatibility and interoperability with other GNSS systems. Unlike the older L1 C/A signal, L1C offers a modernized modulation scheme and improved error correction capabilities. The L1C signal aims to provide better multipath resistance and improved performance in urban environments, which are critical for surveyors using RTK equipment.
L5 Signal
The GPS L5 signal, designated as the “safety-of-life” signal, operates in the Aeronautical Radionavigation Services (ARNS) band. It is intended for use in applications that require high precision and reliability, such as aviation and search and rescue operations. For surveyors, the L5 signal offers enhanced signal strength and reduced susceptibility to ionospheric errors, resulting in more accurate and reliable RTK positioning.
GLONASS (Global Navigation Satellite System)
L3 CDMA Signal
GLONASS is introducing the L3 CDMA signal, a new code-division multiple access (CDMA) signal designed to complement the existing frequency division multiple access (FDMA) signals. The L3 CDMA signal aims to improve interoperability with other GNSS systems and provide better accuracy and reliability for users. This advancement is particularly beneficial for RTK applications, where signal quality and availability are paramount.
L1 and L2 CDMA Signals
In addition to the L3 CDMA signal, GLONASS is planning to enhance its L1 and L2 signals with CDMA technology. These improvements will further align GLONASS with modern GNSS standards, offering increased signal robustness and accuracy. Surveyors using RTK equipment can expect more reliable positioning in diverse environments, from urban areas to remote locations.
Galileo
E1, E5, and E6 Signals
The Galileo system offers a range of signals, including E1, E5, and E6, designed to provide high accuracy and robust performance. The E1 signal, similar to GPS L1, is used for open service applications, while the E5 signal offers dual-frequency capabilities to mitigate ionospheric errors. The E6 signal is intended for commercial services, providing additional data and enhanced accuracy.
High Accuracy Service (HAS)
Galileo’s High Accuracy Service (HAS) represents a significant leap forward in satellite navigation, offering unprecedented precision for a wide range of applications. The HAS provides free real-time high-accuracy corrections for the Galileo signal, achieving positioning accuracy at the decimeter level. This service is particularly beneficial for professional applications such as surveying, agriculture, and autonomous vehicles, where centimeter-level precision is crucial. By broadcasting additional data via the Galileo E6-B signal, the HAS enhances the performance of Galileo’s Open Service, reducing errors caused by ionospheric disturbances and other atmospheric conditions. The introduction of HAS underscores Galileo’s commitment to delivering reliable, high-accuracy positioning services, positioning it as a leader in the global GNSS landscape.
BeiDou
B1C and B2a Signals
BeiDou is continually expanding its signal offerings with the introduction of B1C and B2a signals. These signals are designed to be compatible with other GNSS systems, facilitating multi-GNSS interoperability. The B1C signal operates in the same frequency band as GPS L1 and Galileo E1, while the B2a signal is aligned with GPS L5 and Galileo E5a. This compatibility enhances the overall performance and reliability of GNSS positioning for surveyors.
Global Positioning and Regional Enhancement
BeiDou’s unique approach combines global positioning capabilities with regional enhancement. The new signals improve the system’s accuracy and reliability, particularly in the Asia-Pacific region. For RTK surveyors, this translates to better performance and higher precision in their measurements, regardless of their location.
Enhanced Accuracy and Precision
The introduction of new signals across multiple frequencies significantly enhances the accuracy and precision of RTK positioning. Multi-frequency capabilities allow receivers to mitigate ionospheric errors more effectively, leading to more reliable and accurate positioning. For surveyors, this means achieving centimeter-level precision even in challenging conditions.
Improved Signal Strength and Quality
New GNSS signals offer improved signal strength and quality, which are crucial for RTK performance in environments with signal obstructions, such as urban canyons and dense foliage. Enhanced signal quality ensures that surveyors can maintain accurate positioning even in areas where signal reception is typically problematic.
Once thought to be impossible, with modern RTK receivers you can now survey under trees with GNSS. This is due to improvements in RTK engines but more importantly is down to the deployment of new more powerful GNSS signals.
Reliability and Redundancy
The introduction of new signals and the expansion of GNSS constellations increase the number of available satellites for positioning. This increased availability enhances the reliability of RTK solutions, as surveyors can receive signals from multiple satellites simultaneously, reducing the likelihood of positioning errors due to signal obstructions or multipath effects.
For those who have used older 4th and 5th generation receivers (like the Hemisphere S320 or Sokkia GRx2), you are probably used to receiving at best 15-20 satellites. On the latest 7th generation receivers, like the Hemisphere S631 or Trimble R12i even on a poor day are going to be receiving signals from 30+ satellites. This is further enhanced by the fact, that unlike older receivers, they can obtain their first fix on any constellation. Older receivers can only obtain a fix on the GPS constellation, and will then bring in other constellations into their RTK solution, whereas new receivers will fix on any constellation.
Mitigation of Multipath Effects
Multipath effects, where signals reflect off surfaces and cause positioning errors, are a significant challenge for RTK surveyors. New GNSS signals are designed with advanced modulation and error correction techniques that mitigate these effects, providing more accurate and reliable positioning in multipath-prone environments. This makes a huge difference when surveying under trees.
Interoperability and Compatibility
The compatibility of new signals across different GNSS systems allows for greater interoperability, enabling receivers to use signals from multiple constellations. This interoperability enhances the robustness and accuracy of RTK positioning, as surveyors can leverage the strengths of different GNSS systems to achieve the best possible results.
Receiver Technology Advancements
Modern GNSS receivers are designed to take full advantage of the new signals, incorporating advanced processing techniques and algorithms. These receivers offer improved performance, faster initialization times, and greater resilience to signal degradation, providing surveyors with more reliable and accurate RTK positioning.
The Athena RTK engine from Hemisphere is a good example of this. It wasn’t until the introduction of the Hemisphere S631, which can see all currently available GNSS signals, that the true potential of the engine was reached.
Time to Fix and Convergence Time
The use of multiple frequencies and advanced signal processing reduces the time required to achieve an RTK fix, allowing surveyors to begin their work more quickly. Faster initialization times enhance productivity and efficiency, particularly in dynamic environments where rapid positioning is essential. Check out our video below we compare newer and older RTK technology to see how the two perform next to one another.
Improved Convergence for PPP (Precise Point Positioning)
New GNSS signals also improve the convergence time for Precise Point Positioning (PPP), a technique that offers high precision without the need for a base station. This improvement expands the range of applications for surveyors, providing greater flexibility and accuracy in various surveying tasks. Services like NRCAN’s PPP and NOAA’s OPUS are free services that allow you to post process static points. See below for an idea of static data recording works.
While the introduction of new signals and advanced receiver technology may lead to higher initial costs for RTK equipment, the long-term benefits often outweigh these expenses. Surveyors can achieve higher accuracy, reliability, and efficiency, leading to cost savings in the overall surveying process.
Cost-Benefit Analysis
A thorough cost-benefit analysis reveals that the investment in new RTK equipment is justified by the enhanced performance and productivity gains. Surveyors can complete projects more quickly and accurately, reducing the need for rework and improving client satisfaction.
With the use of new sensors that are integrated into RTK, like IMU tilt sensors, this can mean a significant difference in performance. With tilt sensors, surveyors can complete projects in half the time as before!
A GIS tablet being used to record the position and condition of a fire hydrant. Using FieldGenius, it is very easy to record the position and all relevant information on the condition of an asset.
Several case studies demonstrate the impact of new GNSS signals on RTK surveying. For instance, a construction project in an urban area showed significant improvements in positioning accuracy and reliability when using multi-frequency GNSS receivers with the latest signals. Similarly, a land surveying project in a remote location benefited from the increased satellite availability and improved signal quality, achieving precise measurements despite challenging conditions.
Comparative analysis of RTK systems using old versus new GNSS signals highlights the advancements in positioning accuracy and reliability. The new signals provide more robust performance, especially in environments with signal obstructions or multipath effects. Surveyors can rely on the latest technology to achieve high-precision results consistently. Check out our video below comparing older receivers to the latest 7th generation technology.
Technological Innovations
The future of GNSS technology holds promising advancements, including further improvements in signal modulation, error correction, and receiver technology. Innovations such as multi-constellation integration, advanced signal processing algorithms, and enhanced real-time correction services will continue to push the boundaries of RTK positioning accuracy and reliability.
Challenges and Limitations
Despite the advancements, several challenges and limitations remain. Technical issues such as signal interference, atmospheric disturbances, and multipath effects still pose obstacles to achieving perfect positioning accuracy. Additionally, regulatory challenges and the need for international cooperation in GNSS signal standardization must be addressed to ensure the seamless adoption of new technologies.
The future of GNSS technology is poised to bring significant improvements to surveying with RTK equipment. The introduction of new signals in GPS, GLONASS, Galileo, and BeiDou systems enhances positioning accuracy, reliability, and interoperability. Surveyors using RTK technology will benefit from faster initialization times, improved signal quality, and increased satellite availability, leading to more precise and efficient surveying processes. As GNSS technology continues to evolve, surveyors can look forward to even greater advancements, enabling them to achieve unprecedented levels of accuracy and productivity in their work.
The primary advancements in GNSS signals include the introduction of new signals such as GPS’s L1C and L5, GLONASS’s L3 CDMA and enhanced L1 and L2 CDMA signals, Galileo’s E1, E5, E6 signals, and High Accuracy Service (HAS), and BeiDou’s B1C and B2a signals. These signals improve accuracy, reduce errors caused by ionospheric disturbances, and enhance signal strength and quality, making RTK surveying more reliable and precise.
Galileo’s High Accuracy Service (HAS) provides free real-time high-accuracy corrections, achieving decimeter-level positioning accuracy. This is particularly beneficial for surveyors as it enhances precision without the need for additional correction services. HAS improves the overall performance of the Galileo system, reducing errors from atmospheric conditions and making RTK positioning more reliable.
Multi-frequency capabilities allow GNSS receivers to mitigate ionospheric errors more effectively by using signals from multiple frequencies. This leads to more accurate and reliable positioning, even in challenging environments. For RTK surveyors, this means achieving centimeter-level precision, faster initialization times, and reduced convergence times, enhancing overall productivity and efficiency.
The introduction of new GNSS signals and the expansion of satellite constellations increase the number of available satellites for positioning. This enhances the reliability and redundancy of RTK systems, as surveyors can receive signals from multiple satellites simultaneously. It reduces the likelihood of positioning errors due to signal obstructions or multipath effects, ensuring consistent accuracy in diverse environments.
While upgrading to new RTK equipment compatible with the latest GNSS signals may involve higher initial costs, the long-term benefits often outweigh these expenses. Enhanced accuracy, reliability, and efficiency lead to cost savings in the overall surveying process. Modern receivers offer improved performance, faster initialization times, and greater resilience to signal degradation, resulting in quicker project completion and reduced need for rework, ultimately improving client satisfaction.
Bench Mark Equipment & Supplies is your team to trust with all your surveying equipment. We have been providing high-quality surveying equipment to land surveyors, engineers, construction, airborne and resource professionals since 2002. This helps establish ourselves as the go-to team in Calgary, Canada, and the USA. Plus, we provide a wide selection of equipment, including global navigation satellite systems, RTK GPS equipment, GNSS receivers, and more. We strive to provide the highest level of customer care and service for everyone. To speak to one of our team today, call us at +1 (888) 286-3204 or email us at [email protected]
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