GNSS Technology Update

Speaker: Eric Gakstatter Contributing Editor – GPS World

Editor - Geospatial Solutions Presented at: Association of Petroleum Surveying & Geomatics

Houston, TX April 7, 2015

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Agenda

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- GNSS Infrastructure advancements

- Sources of GNSS corrections

- Space Weather

- Trends

GNSS is the new GPS

GNSS = Global Navigation Satellite System

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GNSS technology is going to advance significantly more in the next 5 years than it has in the past 10

years

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GNSS Infrastructure

ACTIVE GNSS:

-GPS (USA)

-GLONASS (Russia)

-SBAS: WAAS (North America), MSAS (Japan)

EGNOS (Europe), GAGAN (India), Omnistar, RTX, Terrastar, Starfire,

Starfix

-QZSS Regional (Japan)

-BDS Regional (China)

PLANNED GNSS:

-Galileo (Europe)

-BDS Global (China)

-SBAS: SDCM (Russia)

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Augmentation

Regional:

-RTK Networks/Clusters (Public and Commercial)

-Public SBAS (WAAS, etc.)

-Commercial SBAS (Omnistar, RTX, Terrastar)

-DGPS

Global:

-Commercial SBAS (Omnistar, RTX, Terrastar, Starfire, etc.)

-Public PPP (RT GPS)

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• Not only is GNSS receiver technology constantly evolving, so is the GNSS infrastructure (satellites, signals and control).

• This is one of the reasons that the GNSS industry is so dynamic and will be for the foreseeable future.

• These changes will affect the way that GNSS mapping and surveying users perform their work. Better, faster, cheaper.

GNSS is Changing

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GPS Constellation Status

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• Four GPS launches scheduled in FY2015. The most in one year in a long time.

• Oct. 2014, Mar 2015, June 2015, Oct 2015

• After that, one more II-F model left to launch.

• Model IIF = L1 C/A, L1/L2 P(Y), L2C, L5

• Then, it’s time for GPS III satellites.

• Model III = L1C, L1 C/A, L1/L2 P(Y), L2C, L5

GPS Constellation

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• There are currently 31 operational GPS satellites.

• 15 x GPS Block IIA/IIR. L1 C/A, L1/L2 P(Y)

• 7 x GPS Block IIR-M. L1 C/A, L1/L2 P(Y), L2C

• 9 x GPS Block II-F. L1 C/A, L1/L2 P(Y), L2C, L5

• L2C = More robust iono correction for high precision positioning. No need for cross-correlation (semi-codeless).

• L5 = Similar to L2C, but stronger signal @ 1176 • Civil signals (black, red), Military signals (blue)

•

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GLONASS

Russia’s Satellite Navigation System

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• Declared fully operational in December 2011.

• ~24 operational satellites. Most since 1997.

• A valuable augmentation to GPS. Not used as a stand-alone system.

• Valuable to high-precision users (RTK, sub-meter) because it increases productivity.

• Adds ~6-10 more satellites.

• Increases productivity, not necessarily accuracy.

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• Transitioning to CDMA radio design on satellites.

• Glonass-K launched Dec. 2014.

• Up to 9 Glonass-M satellites to launch 2015/2016.

• Ultimate constellation expansion to 30 satellites.

• Transitioning to PZ-90.11 geodetic system. Aligned with ITRF at the mm-level.

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Galileo

Europe’s Satellite Navigation System

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• First four operational Galileo satellites are test sats converted to operational sats (4).

• 1st production launch last Fall. Limited success. A pair injected into the wrong orbit (6).

• 3/27/15 production launch pair successful (8).

• Two more launches scheduled this year (12).

• Constellation of 18 operational Galileo satellites projected in 2016.

• Highly compatible with GPS L1/L5. No L2.

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BDS (Beidou)

China’s Satellite Navigation System

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• More high-precision GNSS receivers are sold in China than the rest of the world combined.

• BDS is currently a regional system of satellites orbiting in a figure eight pattern above China that add ~14 satellites in addition to GPS and GLONASS.

• The RTK environment in China is better than any other place in the world due to the significant number of satellites in view.

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• China plans to offer a 30-satellite constellation by 2020, some speculate they’ll have it complete by 2017.

• Most recent launch was last week (March 30).

• The launch is believed to be the first Beidou-3 M1 satellite and the beginning of Beidou’s Phase III program, which is a 30-satellite global constellation.

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• GPS+Galileo = 20 average satellites in view.

• Add 30 more from BDS and 24 from GLONASS.

• 30-40 satellites in view using 4 constellations.

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SBAS

Satellite-Based Augmentation System

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• SBAS – WAAS/EGNOS/MSAS/GAGAN. Free source of GPS L1 corrections.

• SBAS was designed for aviation, but used widely by geospatial professionals as an accurate source of GPS L1 corrections.

• SBAS was designed primarily for integrity, but can be optimized for accuracy to achieve sub-meter precision.

Public SBAS (sub-meter)

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• Commercial PPP SBAS (decimeter world-wide subscription services):

- RTX, Omnistar

- Starfire

- Terrastar

• Public PPP SBAS (free decimeter world-wide service):

• IGS RT <rt.igs.org>

PPP SBAS (decimeter)

OmniStar/Starfire/Terrastar

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• Commercial RTK Networks • - Surveying equipment dealers

• - GNSS eq. manufacturers – Trimble/Leica/Topcon

• Commercial RTK Clusters • - Agriculture

• Public RTK Networks • - State agencies (eg. Dept of Transportation)

• Public RTK Clusters • - Plate Boundary Observatory (PBO)

RTK

Leica SmartNet RTK Bases

South Plains RTK Cluster – 12m acres

TxDOT RTK Bases

PBO RTK Bases

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• Omnistar – ITRF08 current day epoch

• WAAS – ITRF08 current year epoch

• DOT RTK Networks – NAD83/2011 2010.0

• NGS CORS streaming (discontinued) – ITRF00 1997.0

• PBO RTK bases - ???

• Commercial RTK Networks (surveying) - ??? Localize?

• Commercial RTK Clusters (ag) – WGS-84??

Disparate Geodesy

Public RTK Base Stations in the U.S.

Two recent examples of using Public RTK bases:

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Public RTK Base Stations in the U.S.

Case #1. Colorado.

-Windows Mobile data collector w/AT&T SIM card for internet connectivity

-~12 mile baseline

-Accuracy: 1.9cm horizontal RMS. Adjusted from ITRF00 1997.0 to NAD83.2011 2010.0 using HTDP

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Public RTK Base Stations in the U.S.

Case #2. California (SF Bay Area)

-Samsung Note smartphone (Android) running AutoCAD 360.

-~5 mile baseline, 0.75” precision

- Accuracy: ????

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Trending towards real-time decimeter (PPP) and centimeter positioning (RTK)

Never in history has real-time, high-precision technology been so available and affordable.

And we’re only just beginning…………………….

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Trends

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High-Precision GNSS Technology

The Next 5 Years

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The Next 5 Years

• Complete hybrid L5 constellation (GPS/Galileo/BDS).

• Cheaper/more accurate GNSS receivers.

• Initial deployment of Europe’s Galileo and Chinese BDS.

• Continued proliferation of RTK Networks.

• Further refinement of PPP real-time services (eg. Trimble RTX, IGS-RT, others).

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• The new GPS L5 signal will result in very low-cost L1/L5 receivers capable of cm-level horizontal/vertical precision.

• High-precision GPS receivers trending towards commoditization.

• RTK on your mobile phone by 2020?

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• GNSS performance around obstructions such as tree canopy, buildings, terrain blockage.

• Geodesy – datums, coordinate velocities. Combining disparate data sets.

• Communication for real-time GNSS corrections.

Three Gotchas

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Velocities

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• Don’t know what you have.

• Simplicity vs. accuracy. Geospatial software operators follow the path of least resistance.

• Transformation workflows are not simple or understandable.

• Velocities are a difficult concept for the average geospatial specialist.

• Mainstream workflows to deal with velocity models are largely non-existent.

• Velocity models are a work in progress.

The Geodesy Headache

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• The ability to collect high-accuracy geospatial data is cheaper and easier than ever before.

• Stewards of geospatial data are largely ill-equipped to accurately deal with disparate data sets.

• Geospatial workflows are largely ill-equipped to accurately deal with disparate data sets.

• Velocities are a foreign concept to most geospatial data stewards.

• Velocity models are a work in progress.

Geodesy Takeaways

Comments?

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Questions?

Eric Gakstatter

Contact Information: egakstatter@gpsworld.com

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