Modernized GPS, Galileo, GLONASS and COMPASS signals are all coming on line over the next few years. Augmentation systems such as EGNOS, WAAS and the soon to be GAGAN and QZSS systems add to the mix of signals and technologies available to those developing GNSS technology. At the same time, navigation and positioning applications are becoming more widespread, with end user demands increasing. A significant amount of research and development is currently underway by the technology and applications development community to respond to this expansion in capabilities.
Spirent, as an official provider of test systems to support the development and in-orbit validation of the Galileo project, understands the issues developers face. Spirent Galileo systems are interoperable with Spirent GPS, SBAS and GLONASS simulators, enabling a full multi-system, multi frequency test environment.
Spirent Solves Your Critical Test Challenges
The use of a GPS, Galileo, GLONASS or SBAS simulator enables controlled, repeatable performance testing at nominal and extreme or error state conditions. Only using an RF simulator is it possible to characterise fully, receiver performance in all conditions. By integrating a simulator with other equipment it is possible to realistically test and optimize application performance and experiment with new technology areas.
Global Navigation Satellite System (GNSS) is a general term for a system that provides navigation and other services to users worldwide. Each GNSS employs a constellation of satellites, which broadcasts signals processed by GNSS receivers to determine location, speed, and time for users anywhere in the world. Examples of GNSS include GPS, GLONASS, and Galileo.
A GNSS simulator provides an effective and efficient means of testing GNSS receivers and the systems that rely on them. A GNSS simulator provides control over the signals generated by GNSS constellations and over the global test environment all within a box, so that testing can be conducted in controlled laboratory conditions. GNSS simulators generate the same kinds of signals transmitted by GNSS satellites, thus GNSS receivers process the simulated signals in exactly the same way as signals from actual satellites.
In most cases a GNSS simulator provides a superior alternative for testing compared to using actual GNSS signals in a live environment. Unlike live testing, testing with simulators provides full control of the simulated satellite signals and the simulated environmental conditions. With a GNSS simulator, users can easily generate and run many different scenarios for diverse kinds of tests, with complete control over
- Date, time, and location. Simulators generate GNSS constellation signals for any location and time. Scenarios for any location around the world, or in space, with different times in the past, present, or future, can all be tested without leaving the laboratory.
- Vehicle motion. Simulators model the motion of the vehicles such as aircraft, ships, or automobiles. Scenarios involving vehicle dynamics for different routes and trajectories anywhere in the world can all be tested without moving the equipment being tested.
- Environmental conditions. Simulators model effects that impact GNSS receiver performance, such as atmospheric conditions, obscurations, multipath reflections, antenna characteristics, and interference signals. Various combinations and levels of these effects can all be tested in the same controlled laboratory environment.
- Signal errors and inaccuracies. Simulators provide control over the content and characteristics of GNSS constellation signals. Tests can be run to determine how equipment would perform if various GNSS constellation signal errors occurred.
Testing with simulators is the widely-accepted best practice for validating the performance of GNSS receivers and systems in many different scenarios and operating conditions in a controlled laboratory environment. Simulators are used extensively in academia and industry, in virtually all GNSS receiver manufacturing and major system integration, and in many different application fields, including navigation, positioning, telecommunications, aviation, automotive, and space, for both civilian and military applications. Using simulators facilitates several stages of research and product development, including requirements analysis, design and development, integration, production, maintenance, and support.
GNSS simulators provide many benefits, including
- Control. Simulators allow complete control over all aspects of test scenarios, including GNSS constellation signals and environmental conditions.
- Flexibility. Users can easily define different scenarios for different testing needs.
- Completeness. Equipment can be tested under different operating conditions, ranging from nominal to extreme, including conditions that are impractical or impossible to produce in live testing.
- Repeatability. Test scenarios are the same every time they are executed.
- Reliability. Because all test conditions are controlled, test results are reliable, and equipment performance can be evaluated against known truth data.
- Cost. Tests are conducted in the laboratory, without extra expenses for field tests and test vehicles.
- Efficiency. Many different tests can be completed in the same laboratory test bed, without reconfiguring or relocating equipment. New test scenarios can be created and executed quickly.
- Future. Simulators provide effective means of testing new and future GNSS capabilities that are not yet supported by actual constellations, such as the GPS L2C and L5 signals and the Galileo system.
A summary of the advantages of testing with GNSS simulators, compared to live testing with actual GNSS constellations, is shown in the table below.
Spirent is the industry leader for GNSS simulator products. Spirent offers several different models of GNSS simulators that support a variety of different applications and cover the full spectrum of civilian and military GNSS testing needs. Spirent products range from basic single-channel simulators, suitable for simple production testing, through multi channel, multi constellation simulators, suitable for the most demanding research and engineering applications.
For more comprehensive testing, Spirent also offers products that simulate additional system elements simultaneously with the GNSS constellation signals, such as inertial sensors, various automotive sensors, Assisted GPS (A-GPS) data, SBAS and GBAS augmentation system signals, and interference signals.
With over 20 years of GNSS simulator experience, Spirent provides GNSS simulators with unparalleled performance and comprehensive support.
Spirent has been supporting and will continue to support commercial product developers, application developers, system integrators and others with a comprehensive range of GPS, GLONASS and Galileo constellation analysers. However if you are not working on Multi-GNSS, you probably will be soon and the Spirent range of Multi-GNSS products are available now.
Multi-GNSS Constellation Simulator
The GSS8000 series has been designed to meet all the demanding requirements of Multi-GNSS research and development teams involved in satellite navigation and positioning systems.
Up to 3 RF carriers, selected from a range of constellations and signals, can be accommodated in a single signal generator chassis.
Multi-Channel Fully Flexible GPS/SBAS Simulation System
The GSS6560 12-channel GPS Simulation System offers full user control of scenario creation and data analysis, making it ideally suited for use in a research and development or product development environment.
Multi-Channel GPS L1 C/A Code Scenario Replay Simulator
Especially designed to support testing where the same tests need to be repeated many times.
An easy-to-use, powerful solution for users wishing to replay scenarios, the STR4500 is suited to a wide range of applications, from multiple test runs in a development environment to production and field-testing.
Production Testing Capability
The necessity for high quality signal generation to test GNSS products in a production environment is often overlooked. Spirent produces a range of high quality, high reliability signal generation equipment for this purpose.
Commercial products from mobile handsets to in-car navigation systems need to be tested using consistent, reliable and accurate signal sources in order to ensure a consistent high quality product leaves your factory
Production testing also needs to be fast, reliable and cost effective. Spirent production test GPS simulators have been developed with the demands of manufacturing in mind and support single-channel or multi-channel testing, including GPS L1/L2, with the minimum of operator intervention. For A-GPS testing, assistance data consistent with the test scenario is available.
The majority of satellite navigation applications utilise the GPS C/A code. To this end Spirent offer a number of units for the Commercial and Production markets.
In many production environments, a single channel GPS signal simulator is the preferred way to ensure that each device meets defined parameters. The Spirent GSS6100 is designed specifically for high volume manufacturing test applications for devices that include a GPS L1 C/A code receiver.
The GSS4200 unit offers 6 channels of GPS L1 C/A code to allow a positional fix with representative satellite dynamics and data as part of the production test. For assisted GPS (A-GPS) applications, the assistance data for each scenario is available.