Everything You Need To Know About Global Navigation Satellite System Units (GNSS)
Before we look at the history of the Global Navigation Satellite System (GNSS) or Real-Time Kinematic (RTK), we have to consider the original technology that started it all known as Satellite Navigation. Over time, satellite navigation has become one of the most used and important technologies in the whole world. A satellite navigation system (A.K.A. satnav) is a kind of technology that is used to determine the location of autonomous bodies present on the surface of the earth. To perform this task the satnav technology uses multiple satellites (placed in outer space) to transmit a signal through a channel of transmitter and receiver. These signals can be used for location marking, location tracking, and many other purposes.
This is a basic overview of the Satellite Navigation system as we know it, but today we are taking that a step further to discuss an advanced Satellite Navigation system known as GNSS. Any Satellite Navigation system that has a capacity of global coverage is called a global navigation satellite system or GNSS. But there’s more. GNSS has a secret weapon…
One of the technologies that GNSS often relies on is Real-Time Kinematic or RTK. The Real-Time Kinematic is a type of global satellite positioning technique that helps the GNSS to enhance the accuracy and precision of the targeted data. In terms of positioning, location and ultimate precision, combining GNSS with RTK add a level of exactness unlike anything else. The RTK amplifies the phase signal exchanged between the transmitter and the receiver, thus providing centimetre-level accuracy and real-time signal corrections.
We’ll cover more on the GNSS and RTK combination in future posts but for now, let’s discuss everything you need to know about GNSS.
What Is GNSS or a Global Navigation Satellite System?
The Global Navigation Satellite Systems was initially developed by the US Air-Force, at that time the technology was named as Global Positioning System or GPS and was only restricted to be used only under US defence forces. As time passed by, the GPS technology became accessible to everyone on this planet. Nowadays as smartphones are equipped with GPS and easily accessible to everyone, the governments of several countries have decided to take this technology to a much more advanced, accurate, and long-ranged level. Thus, the birth of Global Navigation Satellite Systems or GNSS was made official to consumers and the private sector.
At present, apart from the US, Russia’s GLONASS and the European Union’s Galileo are the two major operational GNSS working on the surface of this planet. With the emergence of GNSS technology, many sub-technologies have also come into work, these are known as Regional Navigation Systems. The concept of the technology is the same as GNSS but it covers less geographical areas.
How Does a Global Navigation Satellite System or GNSS Work?
The GNSS satellites possess two carrier waves fixed in the L band, namely L1 (1575.42 Mhz) and L2 (1227.60 MHz). The basic purpose of these two wavebands is to transmit signals from the connected satellite to the surface of the earth. According to Techopedia, using L-band technology can reduce your overhead while providing a reliable connection that’s less susceptible to interruption. Implementing L bands with proper antenna positioning provide a number of benefits for agricultural drones, maritime technologies, remote monitoring and more.
On the other hand, the GNSS receivers placed on the surface of the earth consist of an antenna and a processing unit. The purpose of the antenna is to receive the encoded signals from the connected satellites and the job of the processing unit is to decode the signals into meaningful information.
[Note: To determine the position of the single receiver, the GNSS has to collect data from at least three individual satellites].
Each GNSS satellite orbits the circumference of the earth at an interval of 11 hours, 58 minutes, and 2 seconds. The time information of the satellite is broadcasted in codes so that the receiver can determine the time interval in which the code has been broadcasted.
The signals transmitted from the satellite contain coded data that helps the receivers to determine its location and the receiver positions itself accurately with the position of the satellite.
The IC of the receiver calculates the time differences between the broadcast time and the reception time of the coded signal. Once the receiver positions itself accurately with the satellite, the processing unit translates the location of the receiver in terms of latitude, longitude and altitude.
Based on this simple concept, every GNSS works on the surface of this planet.
Applications of Global Navigation Satellite Services
The emergence of GNSS technology has changed the concept of live location tracking at high accuracy with a wide coverage range.
There are some major applications of GNSS that have helped the world to see into a better future.
GNNS for Navigation:
Among all the other technologies, the concept of GNSS has left a major impact on Navigation technology. In recent times GNSS has been included in the automobile industries, now almost every automobile company is integrating the GNSS technology inside their car models. The integration of GNSS technology helps the driver to easily navigate through unknown routes to explore the roadways of the world.
The application of GNSS in the navigation system is not only confined to automobiles, as the technology is now widely used in aircrafts too. The preside location mapping and live terrain updates of the GNSS allows the pilots to avoid the air traffic collisions. Moreover, the GNSS used in the cockpits of an aircraft also uses technologies like WAAS or GBAS (LAAS) to increase the accuracy of the track.
What is WAAS? According to the Federal Aviation Administration, unlike traditional ground-based navigation aids, the Wide Area Augmentation System (WAAS) provides navigation services across all of the National Airspace System (NAS). The WAAS provides augmentation information to GPS/WAAS receivers to enhance the accuracy and integrity of position estimates.
What is GBAS or LAAS? Historically, the Federal Aviation Administration once referred to what we now call GBAS as LAAS. According to the Federal Aviation Administration website, Ground-Based Augmentation System (GBAS) is a system that provides differential corrections and integrity monitoring of Global Navigation Satellite Systems (GNSS).
Apart from the wide range of GNSS applications in automobiles and aircraft, GNSS is also used to navigate boats and ships on the surface of the water.
[Note: Ships use a GNSS function unit named, “Man Overboard” or MOB. This function allows the crew of the ship to accurately mark the position of the person who has fallen overboard.]
GNSS for Surveying and Geological Mapping:
Surveying and Geological mapping is another major application of GNSS.
Most of the GNSS receivers use the signal data generated from the L1 wave frequency to perform Geological mapping. It possesses an accurate crystal oscillator that helps the wave to reduce clock errors while mapping. Researchers can also perform high precision measurements by calculating the relevant displacement between the GNSS sensors.
For example, if an actively deforming area (like a volcano) is surrounded by multiple receiver stations, then the GNSS can come in handy to detect any kind of strain or ground movement.
GNSS Applications for Other Industries:
Apart from these major applications of GNSS, some of the other important applications include,
- Mobile Satellite Communication
- Emergency and precise location-based services
- Weather prediction Improvements
- Photographic geocoding
- And many more.
Inertial Measurement Unit Sensors or INS systems
An inertial measurement unit (or inertial sensor) plays a vital role within Global Navigation Satellite Systems. As we know from our previous discussions that a GNSS system collects data signals from at least three of the orbiting satellites and the signal received by the receivers is incredibly accurate.
However, if the signal gets hampered by some obstructions like trees, boulders or buildings then the signal can no longer provide any accurate positioning. An Inertial Measurement Unit is a kind of inertial sensor that calculates the rotation and acceleration of the moving body to locate its positions.
Let us go a little bit deeper.
An IMU is composed of 6 complementary sensors that are arrayed in three other orthogonal axes, each of these three orthogonal axes is again composed of an accelerometer and a gyroscope.
The job of the accelerometer is to measure the linear acceleration of the moving body, whereas the gyroscope measures the rotational acceleration. Hence by calculating these two together, the sensors can easily provide the accurate location of the moving body.
Combined, the GNSS and the IMU give more power and more accurate navigation solutions to the end-users.
Conclusion: GNSS, It’s Kind of a Big Deal.
With recent technological advancements, many concepts and technologies have changed the playing field for robotics, satellite communication, and navigation as we know it. The Global Navigation Satellite System is a key player among the innovative technologies that have improved everyday life as we know it. What’s more, the RTK allows the GNSS a centimetre-level accuracy level with real-time signal corrections. Adopting GNSS and RTK together provides ultimate accuracy and the top of the line tracking you need. Bottom line, GNSS and RTK make for the most powerful combination on the market today.
Above we have discussed every possible field regarding GNSS and have elaborately discussed its working principles, concepts, and applications.
We hope the article has informed, educated, and inspired you about GNSS and its many applications. Still, have questions about incorporating GNSS? Please contact us today to speak with a GNSS expert!