A huge array of modern products offer positioning, navigation and timing (PNT) capabilities – from wearable exercise trackers to agricultural robots for precision planting and watering. In most of these products, the PNT capabilities will be based on global navigation satellite systems (GNSS) like GPS, Galileo and BeiDou.
However, manufacturers integrating GNSS receivers into products like these may not have deep in-house expertise in GNSS technologies. That can often lead to GNSS receivers being selected predominantly on the basis of cost, size, or the performance information set out in the manufacturer’s spec sheet.
The performance of an integrated GNSS receiver can’t be left to chance
While these considerations are crucial in selecting the right GNSS receiver, independent testing on the part of the integrator is also vital – especially if PNT capabilities are central to the product’s performance.
One reason is that the design of the product itself can impact the performance of the receiver. In the case of an exercise tracker, for example, running in a narrow city street or under tree cover can affect GNSS signal reception, as can the position of the wearable on the user’s body.
While the chipset supplier may have included urban canyons and tree cover among their test scenarios, unless they are designing their products specifically for the wearables market, they may not have combined these scenarios with signal obscuration patterns caused by the user’s body motion.
If the wearable manufacturer doesn’t conduct independent testing, the device may not deliver the promised levels of positioning accuracy. And if the customer discovers these shortcomings after buying the product, it could lead to complaints, returns and damage to the brand.
Important considerations include product design, use case and geography
And that’s just one simple example. There are myriad reasons why product designers and manufacturers should carry out their own GNSS performance tests at key stages of the product development lifecycle — some relating to product design, some to specific use cases, and others to specific geographies.
On the design side, integrators will need to be confident that the GNSS receiver functions as intended when integrated on to a board with other electronic components. If the receiver isn’t adequately isolated, for example, electromagnetic noise from other elements can disrupt satellite signals, causing the product to lose lock or — worse — provide a false reading.
As a use case example, an agricultural robot may need to achieve consistent position accuracy to within 10cm. Fundamental testing might, therefore, focus on factors such as static and dynamic positioning accuracy, time-to-first-fix, and tracking sensitivity. Application-specific testing might need to take into account susceptibility to ionospheric scintillation (if the system is to be used in equatorial regions), as well as positioning performance when augmented with real time kinematic (RTK) corrections.
Geographically, think about a product designed for use in a specific part of the world, like a road tolling system for Singapore, or an autonomous vessel for the Norwegian fjords. The terrain in those areas can create localised signal reception issues—such as multipathed signals or signal obscuration—which the product must be able to handle. That’s only practically possible by simulating these environments and finding ways to iron out any issues they cause.
A new guide to building a test plan for GNSS receiver integration
The way to ensure these issues are identified and dealt with is to build a GNSS test plan that covers the whole product development lifecycle: from selecting a GNSS receiver to ensuring the finished product works as intended as it comes off the production line.
For organisations with less experience of GNSS and related PNT technologies, that might sound daunting. That’s why we’ve created a new eBook,. It sets out the fundamentals of a test plan, and looks at what needs to be tested – and why – at each stage of the product lifecycle.
We explain everything from how to define your test requirements, to getting the right balance between lab-based simulation, RF record & playback, chamber testing, and live-sky field testing. We also show how Spirent products – from our flexible GSS7000 and GSS9000 GNSS simulators to our lightweight GSS6450 record & playback system – can provide the right blend of realism and reliability to deliver test results you can rely on.
The eBook finishes with a useful checklist to help ensure you’ve covered everything necessary to bring a high-quality product to market that delivers the level of performance you’ve promised your customers.
If you’re planning to integrate a GNSS receiver into a new product or system,.