For a technology initially designed solely for military use, GPS has made steady inroads into the commercial world since it was made available for civilian use in 1994. Today, GPS positioning is a feature of a huge range of consumer products, from in-vehicle navigation systems and smartphones, to shopping trolleys and even rat pellets.
But when a company releases a location-aware device that gives inconsistent or inaccurate location reports, critics and consumers alike take notice.
And in our increasingly connected world, dissatisfied customers have no trouble voicing their frustrations on their social platforms of choice – potentially causing commercial damage to your brand.
Design decisions affecting position accuracy
When you’re designing, testing or refining a new device for the commercial market, there’s a lot to consider: the device’s form factor, receiver design, internal circuitry, antenna placement, software algorithms, battery life, and so on.
All of these design decisions can have an impact on the device’s ability to accurately receive and interpret GPS or other GNSS (Global Navigation Satellite System) signals.
For GNSS receiver integrators at commercial device manufacturers, perfecting a new design is a continuous process of iterating, testing and optimizing a variety of factors, including:
Chipset – Many different GPS chips and chipsets are available, with varying levels of quality in terms of accuracy, precision and integrity
Antenna – The design and placement of the antenna is a critical consideration: to ensure positioning accuracy it must have a clear view of the sky and be resistant to interference
Shielding – GPS receivers must be shielded from other RF components within the device to protect them from interference. Without appropriate shielding, accuracy can be compromised.
Multi-GNSS – Receivers that support multiple GNSS constellations, such as GPS, BeiDou and GLONASS, can improve position accuracy, particularly where the view of the sky is constrained
Software – On-board software algorithms can affect how the device interprets and displays GPS data
External factors affecting position accuracy
The average GPS device will also have to contend with external factors such as:
Atmospheric interference – solar storms and ionospheric activity can impact the accuracy and availability of the GPS signal
Multipath effects – caused by GPS signals reflecting off tall buildings or other physical structures, potentially causing the device to report an inaccurate location
RF interference – noise from nearby cell towers, radio transmitters and jammers that can compromise GPS signal accuracy or block the signal entirely
Signal loss and reacquisition – depending on the device, users may expect it to continue to report an accurate position even when satellites are not in view (e.g. when it is indoors or underground), and regain a position fix very quickly once satellites are in view again
To ensure your device reports an accurate position at all times, it’s essential to test its performance in all of the scenarios and conditions it may encounter in the real world.
And that’s something that’s impossible to do simply by testing it with “live” satellite signals in the sky above the test facility. Rather, it requires extensive, lab-based simulation to model and test many different combinations of GPS signal conditions, design decisions and electromagnetic interference.
Watch our video to find out more
We’ve encapsulated the challenges for commercial device manufacturers in this short video. Watch it now to discover:
Why GPS accuracy is increasingly important to users of location-aware devices
Why live-sky testing can’t give you all the answers you need about your device’s accuracy
How lab-based simulation can be complemented with a Record & Playback solution to record the real-world signal environment and replay it in the lab for faster, more reliable field testing
Talk to Spirent
Testing GPS and other GNSS positioning, navigation and timing accuracy is an evolving process. Spirent is a leading expert in testing for GPS accuracy in commercial devices, and can help you acquire the tools, procedures and best practices needed to ensure GPS accuracy in your commercial device.