ION GNSS Conference Peers into the Future of Surveying

September 1, 2009  - By
Image: GPS World

The Institute of Navigation’s Global Navigation Satellite Systems (ION GNSS) conference is one of my two favorite industry events of the year; the other being the ESRI conference. At ESRI, I mix it up with GPS technology users, listen to what they are doing and what they want to do with the technology. At ION, I listen to GNSS designers and researchers.

ION GNSS is where these heady folks come together to share ideas and show the fruits of their labor. It’s also a place where GNSS policy-makers and administrators meet and share ideas. As with GNSS engineers, the administrators and policy-makers are an important part of the future of GPS technology. If a budget gets whacked on a certain GNSS program (say, for example, NDGPS), do you think companies will continue to spend R&D dollars on that technology? If you want to know the future of GNSS and how it will affect surveying, look at R&D today.

What’s so fun for me about ION GNSS is seeing where engineers spend their money and time. The research they present today will be in products you can use tomorrow.

But first, be sure to sign up for my free webinar to be held on September 15. I’ll be talking about modernized GPS signals (L2C, L5) and GLONASS. Do they (or in the case of L5, will it) really make a difference? Let’s talk. I’ll take your questions online after making a presentation.

I hope I’ve made this clear in the past and if not, here goes. I’m not a GNSS scientist. Not even close. Yes, I’ve managed product development where we integrated GPS technology and software to create surveying and mapping products. Yes, I managed the software and hardware engineers who made those products come to life. But if you asked me to write a line of C code or design a circuit, my 17 year old could finish it before I could start. I’m a block diagram sort of person that sees the big picture and communicates my vision reasonably well. And I listen to people, a lot.

Look at some of the ION GNSS presentation tracks below. Keep in mind that each one of these tracks has six to a dozen research papers within it — and these are only 11 of the more than 40 tracks at the conference. A full list of panel descriptions and speakers is available.

  • Multi-sensor Navigation
  • Urban & Indoor Navigation Technology I
  • Surveying & Geodesy
  • GNSS Space-Based Augmentation Systems (SBAS)
  • Multipath Effects and Mitigation
  • Next-Generation GNSS Integrity
  • PPP and Network-based RTK
  • Software Receivers
  • Atmospheric Effects and Modeling
  • GNSS Inertial Navigation Systems
  • GLONASS Modernization, QZSS & other GNSS

Just as a sampling, here are a few abbreviated abstracts from the above sessions:

Development and Field Testing of a DSP-Based Dual-Frequency Software GPS Receiver
B.W. O´Hanlon, Cornell University; T.E. Humphreys, University of Texas at Austin; M.L. Psiaki, P.M. Kintner, Jr., Cornell University
A real-time software GPS receiver for the L1 C/A and L2 C codes has been implemented on a Digital Signal Processor (DSP) and tested in a scintillation environment. This receiver is being developed as a low-cost space weather instrument with improved tracking robustness in comparison to a traditional semi-codeless dual-frequency receiver and with flexibility in its choices of signal tracking algorithms and data outputs. The receiver is capable of tracking 12 L1 C/A and 12 L2 C channels while also calculating receiver position and velocity and total electron content (TEC). The current work is a direct continuation of the work presented in Ref. 1. This work discusses several modifications to the software developed earlier, challenges addressed in updating the receiver to be easily adapted to new GNSS signals (e.g., L2C), and lessons learned from operation during ionospheric scintillation.

Improving Real-Time Kinematic PPP with Instantaneous Cycle-Slip Correction
S. Banville, R.B. Langley, University of New Brunswick, Canada
Over the last decade, precise point positioning (PPP) proved to be a powerful processing strategy. It vastly spread in several fields of applications such as atmospheric sciences, geodynamics, surveying in remote regions, processing of large networks, etc. On the other hand, the success of this technique in kinematic mode (with a moving receiver) is still muted due to a rather long convergence period required to obtain a centimetre level of precision. Several efforts were mounted to overcome this limitation, which led to the possibility of fixing carrier phase ambiguities to integers, which is the key to reducing the convergence period. In our approach, both carrier-phase and pseudorange measurements are included in the processing which allows estimating, not only receiver position change and receiver clock offset variation, but also cycle-slip parameters. Since time-differencing over short time spans is used, the assumption that instrumental biases cancel out seems reasonable. Hence, the cycle-slip parameters estimated are integers and conventional ambiguity search methods can be used to statistically determine the optimal cycle-slip (ambiguity) combination. Once the correct combination of integer cycle slips has been determined, their effects can be removed from the carrier-phase measurements, and the PPP processing can be executed without having to introduce new ambiguity parameters in the estimation filter. The benefit of this additional step is that a continuous time series can be obtained for the receiver coordinates, without the need for a new undesirable convergence period.

Augmenting Low-cost GPS/INS with Ultra-wideband Transceivers for Multi-platform Relative Navigation
A. Vydhyanathan, H. Luinge, M. Tanigawa, F. Dijkstra, Xsens Technologies B.V., The Netherlands; M.S. Braasch, M. Uijt de Haag, Ohio University, USA
This paper explores the use of impulse radio based Ultra-wideband transceivers to augment the low-cost GPS/INS navigation estimates in GPS-challenged/denied environments for multi-platform relative navigation. Such low-cost GPS/INS systems are increasingly being used in automobile, aerospace and marine applications for vehicle dynamics analysis, performance testing, Unmanned Aerial Vehicles (UAV) and Unmanned Ground Vehicles (UGV), autonomous attitude and navigation control and camera/LADAR stabilization and correction. The architecture and algorithm developed in this paper has independent ´loosely-coupled´ GPS/INS EKF´s running on each platform. A separate filter then takes the independent filter outputs and combines them with the ranges derived from the Ultra-wideband broadcasts to output relative navigation estimates.

The Benefits of Multi-constellation GNSS: Reaching up Even to Single Constellation GNSS users
B. Bonet, I. Alcantarilla, GMV, Spain; D. Flament, C. Rodriguez, EGNOS Project Office, ESA, France; N. Zarraoa, GMV, Spain
Europe has launched, under the European Space Agency’s (ESA’s) European GNSS Evolution Programme, the MRS initiative. MRS standing for Multi-constellation/multi-frequency Regional System, the initiative is putting different teams of experts into the exciting goal of defining the paths for the most successful GNSS usage on a future of multiple choices.  ESA has prepared a detailed experimentation plan aimed to proof the benefits that the multi-constellation approach can provide to today´s GNSS users. This plan covers a wide range of objectives covering different user domains (aeronautical, land mobile, maritime) eq
uipped with different types of receivers. This set of experimentations will rely on the deployment of several Test Beds combining multi constellation multi-frequency processing and several broadcast channels (GEO, MEO, terrestrial). Among the first experimentations planned, there are some devoted to experiment and validate the performance benefits for SBAS users (GPS L1 only first then GPS/GLONASS or GPS/Galileo — dual-frequency SBAS users). This paper presents the outcome of the first step of this experimentation campaign, which has been performed based on the magicSBAS tool, a flexible SBAS processing platform, able to acquire single and dual frequency GLONASS data, in addition to GPS, to compute and provide both standards SBAS corrections and integrity, as well as augmentation to GLONASS.

From studying the track titles and abstracts, one can read between the lines and take a peek into the future of GNSS products. It’s clear to see that software receivers, SBAS, other GNSS, other sensor technology, PPP, atmospheric modeling and mitigation, and more reliable positioning all are active R&D topics that will mold the products in our future…some now and some a few years out.

I really enjoy this “look into the future” and will do my best to communicate the highlights to you. Our GPS World team will be at the ION GNSS conference in full force. Daily blogs will be written by several editors including myself. The GPS World website will be updated daily so be sure to check in throughout the week (September 21-25.)

The ION GNSS conference doesn’t actually start until Wednesday (kick-off is the plenary Tuesday evening) of that week. The Civil GPS Service Interface Committee (CGSIC) schedules their annual meeting on the two days prior to the ION GNSS conference. If you aren’t familiar with the CGSIC, I wrote an article about it a couple of years ago. Briefly, CGSIC is the body through which the civil GPS community can communicate with GPS authorities.

The two days of CGSIC meetings are chocked full of fantastic presentations from the status of GPS/GLONASS/Galileo/SBAS/NDGPS programs to presentation by users of GNSS. Normally I see the agenda posted on the CGSIC website, but I haven’t seen it there ye but check back in a day or two and I bet it will. Typically, the first day are program status briefings (GPS, GLONASS, QZSS, Galileo, SBAS, NDGPS, etc.). The second day contains breakouts sessions from the different subcommittees (US States and Localities, Survey Mapping & Geosciences, International and Timing). I’ll be giving a briefing on RTK Networks Tuesday at the US States and Localities subcommittee breakout session.

The guy who kicks my butt all over the landscape when I don’t file this column on time, GPS World editor Alan Cameron, also presents at CGSIC on Monday afternoon, with the topic “User Concerns.” For a preview of his presentation, see the latest installment in his Wide Awake blog, Wide Awake on the Midnight Train to Georgia [[]], in which he plays back results from a magazine survey of readers who answered the question, “Where is society going with GPS/GNSS use, and how will that change the GPS/GNSS industry?”

We’ll be blogging on the CGSIC meetings as well. Cameron and I will both have digital video recorders in our traveling bags, and we’ll post footage of highlights during the week. That’s another great way for you to get a bit closer to this goldmine of a conference.

In other notes, only 10 days after it was launched, the latest and last Block IIR-M GPS satellite was declared healthy and ready for service on August 28. Your receiver should be already tracking it and using it. It is identified as PRN05.

Meanwhile, the status of PRN01 (SVN49) that was launched back in March is still unhealthy and not usable. There’s been no significant news since the flurry of reports detailing its flaw a month ago. I suspect the Air Force will make some sort of announcement at the ION GNSS conference later this month with an update and/or plan to deal with the sick bird.

And again lastly, be sure to sign up for my free webinar to be held on September 15. I’ll be talking about modernized GPS signals (L2C, L5) and GLONASS. Do they (or in the case of L5, will it) really make a difference? Let’s talk about it. Sign up here.

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