Centimeter-level positioning will drive the next generation of location-based apps
December 04, 2017
Location-based technologies have made great strides, and in many cases, location of objects can now be pinpointed within a few feet ? but what if close isn?t close enough?
Location-based technologies have made great strides, and in many cases, location of objects can now be pinpointed within a few feet. That’s fine for locating lost car keys, and mobile marketing and basic navigation services. But what if “close” isn’t “close enough?” That’s the issue for many of today’s emerging applications, such as drone delivery, asset tracking, healthcare monitoring, precision agriculture, and—yes—connected cars, where a more precise level of positioning means success or failure.
Companies need a new way of approaching the accuracy conundrum, for both indoor and outdoor applications. Antennas are forging into new territory to drive the market toward more precise location accuracy.
There are dozens of solutions in play for indoor location systems that rely on technologies proven in other areas, such as Bluetooth, Wi-Fi, and assisted GPS, and they’re adequate for ballpark location needs. But precision location—often down to the centimeter level—requires a new way of thinking.
Ultra-wideband (UWB), a low-power technology that’s capable of transmitting large amounts of digital data short distances over wide frequency bands, from 3 to 10 GHz, has emerged as the next-generation option for tracking a wealth of autonomous things. UWB works as a type of indoor GPS, bringing greater precision to indoor applications than do current technologies, and enabling new or enhanced services in warehouse management, healthcare (where’s the closest defibrillator?), and emergency services (exactly where people are located in a burning building).
Beacons using Bluetooth connectivity have been useful for establishing a baseline for indoor location, but the latency limitations make it a poor option for real-time and highly accurate positioning. UWB fills the gap that Bluetooth-enabled beacon technology can’t, calculating distance (down to a few centimeters) by measuring the time it takes the signal to travel from the transmitter to the receiver. Location coordinates can be delivered within milliseconds, enabling the real-time aspect of UWB. In addition, UWB has low power requirements, which give sensors and tags increased battery life in sensors and tags, reducing overall operational costs.
Antennas are crucial to the success of precision indoor positioning via UWB. They need to be able to be small enough to be mounted onto a PCB or embedded within a device without sacrificing performance. Complex antenna performance parameters such as the Group Delay, Polarization and Fidelity Factor must to be considered to deliver the centimeter-level positioning that emerging applications require.
Centimeter-level positioning for outdoor applications is also in high demand, and can benefit from emerging technologies and extra availability of GNSS satellites with higher gain signals. If you’ve ever heard the words “recalculating” from your in-car navigation system, you know that standard locations capabilities aren’t enough for autonomous vehicles, or even drones. Centimeters matter, and there simply isn’t room for error.
To deliver the highest levels of real-time location accuracy and performance, multiple RF bands are needed. Emerging solutions must utilize not only the additional functions of the Galileo, GLONASS, and BeiDou satellite systems, but also the GPS L2 or L5 bands. By developing systems and antennas that cover all three bands, location can be pinpointed within a few centimeters.
In the antenna world, there are two ways to accomplish the GNSS performance needed for centimeter-level positioning:
- Stack-patch antennas that cover the L1, L2, and L5 bands for solutions with low-profile requirements, such as vehicles and UAVs with timing requirements. Patches for different bands are stacked atop each other wedding cake-style to get the best performance for GNSS by optimizing axial ratio. For example, their size makes them a good fit for inside the roof of a vehicle.
- Quad-helix passive and active solutions for applications like base stations that can handle a higher-profile footprint. Quad-helix antennas have better radiation patterns, and can “see” more satellites than a patch antenna can.
As more precise location requirements creep into “outdoor” markets such as precision agriculture, drone use across multiple industries, military applications, the connected car, and a wealth of indoor applications that require precise location capabilities, companies need a new approach to the accuracy conundrum. Centimeter-level positioning provides a good place to start, and antennas will play a key role in enabling those capabilities.
