For systems integrators, GPS simulators are becoming an essential test instrument, primarily because it is difficult to capture GPS signals in indoor locations such as factories and laboratories where the development and verification work is done. Further, bringing in signals from roof mounted antennas is possible, but provides only limited repeatability to testers and can not be fully controlled. Nor can this solution simulate movements, arbitrary places and times, or changing atmospheric conditions.
Integrated GPS technology has become almost a standard feature in mobile phones and other portable communication and computing devices, as well as in cameras and games. Plus there is a growing market for GPS-based applications such as navigation devices for vehicles (stand-alone and integrated), fleet management, logistics, tracking of goods in transit, tracking of people and personal belongings, road tolls, personal training devices, and services related to these applications.
Traditionally the GPS simulator has been affordable only to specialists, such as chip manufacturers and the GPS R&D community. But with GPS technology now entering such a wide range of application areas, demand is fast growing for lower cost equipment for product development and manufacturing test applications among OEMs and systems integrators.
The single channel GSG-L1 is intended for simple, fast, go/no-go factory tests of GPS-receivers integrated into other devices such as mobile phones, navigation devices and tracking systems. The low cost, single channel model facilitates rapid testing during the assembly process, ensuring that the antenna is connected to the GPS receiver module, and that the system can recognize a GPS-satellite. Sensitivity of the GPS receiver is easily tested via the programmable output level.
The 16-channel, GSG-55 has the additional capability of performing accurate testing of navigation parameters as a minimum of 16 channels is required for positioning data. The GSG-55 can also be used to simulate user movements and is suited for both R&D and production test. The benchtop unit is easily portable and requires no external PC control. The front display and control panel of the GSG-55 can be used to edit position, time, trajectory, events (such as signal outtakes), signal data content (ephemeris/almanac), etc.
There are no limitations to the number or scenarios that can be enacted or the scenario replay time. The GSG-55 is supplied with a set of pre-installed scenarios, including some basic trajectories. An advanced user has the option of configuring the supplied data, uploading application specific or customised ephemeris data and trajectories, including data collected using a GPS device and stored in standard NMEA format, as well as entering user-defined satellite data in RINEX format.
Additional technical features of the GSG-55 include built-in support for multiple antenna models, the ability to simulate a range of atmospheric conditions, multipath simulation and 3GPP A-GPS test scenarios. Ethernet, IEEE488 GPIB and USB interfaces are provided. The instrument is suitable for timing receiver testing, providing wide signal output dynamics from –65 to –150 dBm and offering:
• 1-PPS output synchronised with navigation message
• 10 MHz external reference Input from e.g. from an atomic clock
• 10 MHz output as a reference to other test instruments
For OEMs and system integrators, the GSG-55 is intuitive to use, delivering repeatable and reliable testing and verification during development and integration and it is affordable. In particular, the simulator allows developers to verify the behaviour of software, including map handling, map matching and positioning forwarding, and to see how the resulting position solution is handled by the end application.
The GSG-L1 and GSG-55 are already available in the UK on a 4 to 8 week lead time, exclusively from Aspen Electronics. They are fully RoHS compliant. The instruments are manufactured in Sweden by Pendulum Instruments, formerly the test and measurement division of Philips. Pendulum is now part of the US-based multinational Spectracom group.