Applications for GNSS in IoT
There are many applications for precision embedded GNSS antennas for IoT. Obvious uses would include mobile applications such fleet tracking and pay as you go insurance while other applications may not seem as obvious. For instance, using GPS to uniquely identify a specific trash compactor, smart garbage can or even street light. In cases where an IoT device may move but doesn’t move often, adding movement sensors can let you shut-off that receiver to save power once you have acquired a fix on the signal.
GNSS also has other uses besides location; it is an automatic means for setting system time. This can dramatically improve the performance of remote sensor systems by ensuring your time and date stamp are always correct and your device is reporting in when it’s supposed to. In addition, this combination of location and time can give you the timezone setting as well. GNSS reports altitude as well as location and sometimes that altitude information can be combined with other sensor data like barometric pressure for automatic deployment of weather or other sensing systems.
Another less obvious way to make use of GNSS is to deploy either multiple antennas switched into a single GNSS receiver or multiple receivers and antennas to measure the orientation of your system. For example, placing a GNSS antenna on each wingtip of a fixed-wing drone and at the front and back ends of a school bus can let you directly determine the orientation of the vehicle in real time with no magnetic errors or other issues associated with using a digital compass. The further apart the antennas, the more precise the orientation calculation can be. The receivers can be adjacent to each other if required but will not give the same precise results. The feedback can be close to instantaneous as modern GNSS receivers are capable of refreshing at up to ten times a second.
“With autonomous vehicles and other high volume applications creating a mass market need for high precision embedded GNSS antennas and receivers, expect to see dual frequency receivers available to the IoT market by 2019.”
Since GNSS receiver accuracy is mostly limited by variations in ionospheric propagation delays, which for any two receivers near (within a few km) each other, the relative accuracy of the two receivers can be very good. This high relative accuracy can be exploited in specific applications such as determining orientation as mentioned above, precision agriculture, lawn mower robots, invisible fence systems or any other application where relative location can provide sufficient information for use-case.
Why Use Multiband GNSS?
This high precision is achieved by removing the that ionospheric error. In a two receiver system, one receiver is referenced to a physical location, for instance, the corner of a yard for an invisible fence system, and the difference in locations is computed and used for the application rather than the absolute position. The absolute position could vary by several meters but the differential measurement can be accurate to a few centimeters. Any means of removing that ionospheric error will accomplish a similar improvement in accuracy and this is why GNSS systems always use two different frequencies. The satellites send the same information on two different frequencies. The delay through the ionosphere varies in a known way with frequency so by comparing the delay through the ionosphere for the signal on each frequency, one can calculate the ionospheric delay and correct it out resulting in a single (albeit dual frequency or “band”) receiver with centimeter-level accuracy.
With autonomous vehicles and other high volume applications creating a mass market need for high precision embedded GNSS antennas and receivers, expect to see dual frequency receivers available to the IoT market by 2019. Also, as joint CEO, Dermot O’Shea wrote in this article, Centimeter-level positioning will drive the next generation of location-based apps. At Taoglas, we have seen the need for low cost and high precision for a long time which is why we have numerous multi-band GNSS antenna products available already. It is due to this foresight that many of the companies developing multi-band receivers are using our antennas already to test their products.
GNSS still won’t work indoors, but outside it will now be much more accurate.
For more information, please contact our Customer Services Team. We can also test your antenna and customize it for your specific project requirements.