A GNSS (Global navigation satellite system) simulator is a test instrument used to emulate the environment of a GNSS transmitter on a dynamic platform. The emulation of the GNSS environment is done by modelling satellite and vehicle motion, atmospherics conditions, signal characteristics and other effects, to help the GNSS receiver actually navigate according to the test scenario.
To understand the GNSS simulator operation in a better way, we recommend understanding the following associated accessories for the test requirements.
In this RF and Microwave GNSS simulator article, we will cover,
GNSS is the short form of Global Navigation Satellite System (GNSS). GNSS refers to a constellation of space satellites that provide signals that consist of timing and positioning data to GNSS receivers to determine the location on the ground.
GNSS provides global coverage and includes all the satellite constellations like the
The criteria for assessing the performance of Global Navigation Satellite System (GNSS) systems are:
Accuracy of the GNSS systems is the difference between a receiver’s real position, speed or time and the corresponding measured values.
GNSS data continuity indicate the ability of a system’s to function without any internal or external interruption.
The Integrity of a GNSS system’s indicates its capacity to provide a threshold of confidence and, the option to provide an alarm in the event of an anomaly in the positioning data.
Availability of a GNSS system indicates the percentage of time a signal fulfil the above criteria of accuracy, continuity and integrity.
For Example, EGNOS (European Geostationary Navigation Overlay Service ) is used to improve the accuracy of GPS information by validating and correcting signal measurement errors and maintaining the integrity of its signals.
GPS is a global satellite positioning system, it is a navigational satellite constellation belonging to America. GNSS is a term that is used to refer Multi-Constellation Satellite System which includes all the satellite constellations.
I.e. GNSS includes GPS, Baidu, GLONASS, Galileo, IRNSS or many other upcoming constellation systems.
GNSS simulators emulate the environment of a Global navigation satellite system and enable the testing of the GNSS receivers using all current and future signals to predict in the real world scenario. There are mainly two types of GNSS simulators with improved performance and better results based on different simulation technologies.
The Real-Time GNSS Simulator supports constellations like GPS, GLONASS, Galileo, and BeiDou. Real-Time GNSS operates in real-time or as a record and replay mode to define the position, speed, route, date, and time, as well as the number of satellites. Real-Time GNSS Simulator is capable of multipath simulation to supports all types of vehicle simulation via motion commands. These simulators offer real-world scenarios like Attenuation, code delay, doppler shift, and carrier phase offset in each multipath channel.
Software-Defined GNSS Simulator can simulate multiple constellations simultaneously such as GPS, GLONASS, Galileo, BeiDou, and SBAS. This Software-Defined GNSS simulator features an internal processor and software-defined architecture that allows it to simulate hundreds of satellites in real-time. This simulator offers, live sky time synchronization and differential GNSS & multi-vehicle simulation capability. These GNSS simulators will have highly flexible and scale-able architecture.
GNSS systems are used in all most all aspects of daily life to track and forecast the movement of freight and other automotive. It is used to improve efficiency and enhance driver safety in road networks. GNSS Simulators are mainly used in the research and development of these GNSS systems from the design to the implementation stage. GNSS simulators are used for the LAB testing, field verification, after installation system configuration confirmation and calibration of GNSS receivers and other GNSS based systems.
A few of the applications of GNSS systems and Simulators are listed below.
GNSS systems have been used in every aspect consumer market, including the tracking of the goods movements from the factory to the stores. GNSS simulators are used in the R&D of these systems and for the routine field calibration of these instruments. The integrated GNSS receivers in smartphones, support the applications that need to display maps to the location and shows the best route to the locations.
GNSS systems are used for the ground mapping to maintain the Land recorders, constructions, infrastructure development etc. GNSS simulators are used to verify the accuracy of these ground mapping systems and routine checkups.
GNSS systems are used in conjunction with other systems in track, locomotives, rail, cars, maintenance vehicles to monitor from the central monitoring consoles to know the precise location. This GNSS equipment reduces accidents, enhances safety, reduce delays and operating costs. GNSS simulators are used in the monitoring consoles for the routine calibration of this GNSS equipment.
A geospatial information system (GIS) is used to map attributes for, municipal planning, utility companies etc to captures, analyzes, store manages, and present environmental or resource data that is linked to a specific location. The data associated with the position can be provided by a GNSS receiver. GNSS Simulators can be used as a real-time position data provider for GIS systems.
GNSS receivers are used in types of machinery such as excavators, bulldozers, and other farm machinery to enhance the productivity of this equipment, by providing situational awareness and position information during the operator. GNSS simulators are used during the integration testing of these GNSS receivers into these machineries.
GNSS technologies are used in a broad range of applications such as Navigation in unfamiliar terrain or conducting night-time operations using hand-held GNSS receivers. Other military applications like search and rescue during plane crashes and has a rescue beacon supported by a GNSS receiver. GNSS Simulators are used in the testing of these GNSS receivers during the R&D and at the time of integration.
GNSS technology is used to track the movement and placement of containers in a shipping hub, this can improve the operating efficiency of the ports. the cranes equipped with GNSS based steering devices will have improved accuracy and offer safety of operators on the ground. GNSS simulators are used in the ports as part of regular check-up maintenance and calibration.
GNSS systems-based applications are used for farm planning, tractor guidance, field mapping, etc. GNSS applications can automatically guide the movements of the farm equipment, maximize the effectiveness of irrigation systems, save time, fuel, and maximize the efficiency of the operation. GNSS simulators are used in the design of this agricultural equipment.
GNSS satellites are equipped with atomic clocks, which will have accuracy in the range of nanoseconds. The timing signal from the GNSS transmitter is used as part of the position determining process, synchronization of communication systems, electrical power grids, and also where ever precise timing is needed for operation.
Data received from the GNSS can be used to position the systems like bulldozers, hydraulic controls etc. GNSS based applications for the control system increases the efficiency of many constructions works in the industry. GNSS simulators are used in the design and development of these GNSS based control systems.
GNSS information is used to efficiently manage the mining by providing the position information on the computer-controlled display of the trucks and mining machines. Position information is used by blast hole drills to improve the location accuracy and control the depth of each hole.
GNSS systems are used for the testing of the spacecraft parachutes by monitoring the position. This test will help to avoid failure during the operation.
While choosing the GNSS Simulators for test and measurement of GNSS receivers and other systems it is important to check the following specifications.
If the number of supported satellite constellations are more, it is better for the applications. The most common constellations are GPS, Galileo E1, GLONASS L1, BeiDou B1, QZSS, IRNSS (NavIC).
The number of simulated satellite indicate how many satellite in a constellation a GNSS simulator can accurately simulate at a time. If more satellites can support, it will be better for the application and increase the accuracy.
The number of RF output ports indicate, how many DUT it can support at a time. If the number of ports is more, it can support more systems.
Signal accuracy indicates the percentage of variation of generated signal from the simulator to the original GNSS constellation data. Need to select more accurate systems for better test requirements.
The interface includes remote communication, electrical and the RF interface of the GNSS simulators. Need to select as per the systems requirements.
A GNSS simulator creates an environment for the testing of GNSS receivers by modelling satellite motion, signal characteristics, atmospheric effects faced by a Global navigation satellite system.
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