Inside GNSS Media & Research

JUL-AUG 2018

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10 Inside GNSS J U L Y / A U G U S T 2 0 1 8 M y professional involvement with PNT began a little more than 20 years ago when I le my job as a mechanical engineer dealing with nuclear power plant systems and joined the GPS laboratory at Stanford University. GPS had just been declared operational and the impact it was going to have on the world was obvious even to novices like myself. PNT conferences were starting to become GPS- centric and even the IEEE PLANS (now the ION/ IEEE PLANS), a confer- ence once dominated by inertial sensor technology, became over the span of a two or three conference, a GPS (now GNSS) heavy conference. ings have remained that way for a while now. GNSS was the star of the show — other navigation systems were to augment it and "fill in the gaps" when it was unavailable. Even aer the re- naming of the main ION PNT conference (now ION GNSS+ to reflect GNSS plus other sensors), GNSS was still the dominant technology commanding the lion's share of attendees' attention. A seasoned PNT conference attendee of the last decade, however, would have found the recent ION Joint Navigation Conference (JNC) a most jarring experience. Non-GNSS navigation solutions were represented to an equal amount as GNSS. I will confess, I did not go through the program and count the number of GNSS vs. non-GNSS papers, but I am certain I am not far off the mark. I think the trend is going to continue. at is, we are going to see more and more emphasis on non-GNSS PNT solutions. Of course, this is not surprising. GNSS is a mature technology and utility (yes, utility) that people use worldwide. Yes, there is more work that can and should be done to improve the perfor- mance and enhance the robustness of GNSS. Many of the major GNSS unknowns have been worked out. Other solutions that will augment or work in conjunction with GNSS will be the focus on more and more of the work in PNT. e trend I saw at ION JNC raises the following two questions: First, will non-GNSS, ubiquitous PNT solutions that are as accurate and cost-effective as GNSS be avail- able in the near future? Secondly, how near is that future? I believe the question to the first answer is an un- equivocal "yes." ere are at least four reasons why I think this to be so. First, and foremost, the demand for GNSS-like accuracy and ubiquity is there and increasing. In our networked world where the cell phone is almost a necessity, the demand for loca- tion-based service is increasing. e autonomous system wave that is coming (or some may argue has already arrived) is demanding ubiquitous PNT solu- tions. Driverless cars, for example, are going to need lane-level accuracy in environments where GNSS cannot provide that service. is demand will be a driving force for these non-GNSS PNT solutions. Second, inertial sensors (which will be the core of most non-GNSS solutions) are getting better and better while costing less and less. Gyros and accel- erometers that provide a near tactical grade perfor- mance are now readily available. e next step to take these sensors to tactical and ultimately naviga- tion grade performance is not going to be trivial. But it is a problem that a considerable amount funding and talent is being dedicated to worldwide. ird, there is an emergence of a whole range of sensors and systems that can be used to aid and bound the dri of inertial navigators. Not only are they avail- able but their cost is dropping rapidly. ey are also becoming miniaturized just as quickly. A case in point is LiDAR—the days when these sensors were exotic, expensive and bulky are gone. e same is true of heading sensors, RF-signal- based position- ing solutions and signal of opportunity navigation solutions. Finally, and the most exciting reason why I think this capability is just around the corner, is the avail- ability of computational horsepower. A case in point was a remarkable paper presented at JNC which de- scribed an Android app mechanizing a multi-sensor personal navigation system which fused information from a terrain data base, inertial sensors and a baro- metric altimeter using a particle filter. We take it for granted that we can run particle filters on an An- droid phone but this is a feat that was unthinkable just five to 10 years ago. e powerful computations resources now available at one's fingertips (liter- ally) allow mechanizing complex and sophisticated multi-sensor integration schemes which would have been considered a fantasy just a few years ago. So when will these non-GNSS solutions be ready for "prime time?" is is a more difficult question and its answer is really anyone's guess THINKING ALLOWED Non-GNSS Navigation Solutions Show Up Big at JNC DEMOZ GEBRE EGZIABHER FOR INSIDE GNSS "THE POWERFUL COMPUTATIONS RESOURCES NOW AVAILABLE AT ONE'S FINGERTIPS (LITERALLY) ALLOW MECHANIZING COMPLEX AND SOPHISTICATED MULTI- SENSOR INTEGRATION SCHEMES WHICH WOULD HAVE BEEN CONSIDERED A FANTASY JUST A FEW YEARS AGO."

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