GPS World, January 2018

ANTENNAS CHARACTERIZATION GUIDES UAV NAV POSITIONING WITH ANDROID GNSS OBSERVABLES FOR THOSE WHO WANT HIGH ACCURACY BUT DONT NEED IT FULL TIME high productivity dedicated professional solutions may not be cost justified In these cases a positioning as a service subscription could offer a viable use model Achieving precision positioning with just a standard mobile device a correction stream using the mobile devices data connection and a high accuracy positioning application produces a very low barrier to achieving high accuracy BY Stuart Riley Herbert Landau Victor Gomez Nataliya Mishukova Will Lentz and Adam Clare Trimble Inc W e expect that for professional applications that need precision positions a dedicated system that employs a custom GNSS chipset and purpose built applications will continue to be the right solution However it becomes clear that the ubiquity of consumer mobile devices with increasing computing power ruggedness and an expanding feature set presents fertile ground for new development of improved positioning systems that dont have strict professional requirements A range of new use models and applications will be enabled by consumer mobile phones with technology that improves positioning performance The goal of the work presented here is to assess what level of performance can be achieved by using proprietary PVT position velocity time engines utilizing GNSS measurements from the Android GNSS measurement application programming interface API We first review GNSS measurement and positioning performance from a subset of the current Android 18 GPS WORLD WWW GPSWORLD COM JANUARY 2018 phones tablets currently on the market Then we show the position performance achievable using precision engine with measurements from a dual frequency GNSS chipset targeted for the cellular handset market This class of device is expected to be integrated into consumer cellular devices on the market within the next 1 to 2 years Performance of Current Phones We tested various devices including the Nexus 9 which provides phase data and various other Android devices that implement the new API Most devices tested do not support phase data of the few devices tested that do provide phase data all except the Nexus 9 implement GNSS power duty cycling This is a mode where the GNSS chipset is only active for a fraction of each second to reduce power consumption This results in cycle slips each epoch which makes carrier phase processing for real time kinematic RTK unusable During the testing a wide range of performance across devices was observed FIGURE 1 shows the C N 0 for a high COVER STORY