Considerations for Testing GLONASS Considerations for Testing GLONASS Ken Bays, PLSKen Bays, PLS

Lead Geodetic Surveyor, Oregon DOTLead Geodetic Surveyor, Oregon DOTNGS ‘Best Practices for RTN Administration’ WebinarNGS ‘Best Practices for RTN Administration’ Webinar

20 March 201420 March 2014

Mount Hood, OregonPhoto by Daryl Moistnerwww.nevadasurveyor.com

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Ken Bays, Lead Geodetic Surveyor

Randy Oberg, Geodetic Surveyor

OverviewOverview Why test GLONASS?Why test GLONASS? What do we want to test?What do we want to test? Who is involved in the testing?Who is involved in the testing? Issues with GLONASSIssues with GLONASS Planning for testingPlanning for testing Issues with testingIssues with testing

Why test GLONASSWhy test GLONASS Evaluate when Oregon DOT surveyors

should or should not use GLONASS Should we add GLONASS capability to the

Oregon Real-time GPS Network? Benefit to surveyors to know more about

the solutions they are using. Varying manufacturer claims Lots of anecdotal claims and “back-of-the-

envelope” tests out there

What do we want to testWhat do we want to test Testing Productivity

– Does it always help to add GLONASS?– Will GLONASS always enable a solution

in heavy canopy when GPS-only won’t yield a solution?

What do we want to testWhat do we want to test Testing Accuracy

– Is accuracy the same, worse, or better than GPS-only in open and closed canopy.

Some older papers suggest GLONASS degrades accuracy of GPS-only solutions

– But remember the GLONASS constellation was down to 6 or 7 satellites a few years ago.

One manufacturer currently claims “GPS and GLONASS can increase performance AND accuracy by up to 30% relative to GPS only”.

– Is the accuracy increase the same in and out of canopy? Other papers report little accuracy difference when

adding GLONASS to GPS-only.

Who is involved in the testing?Who is involved in the testing? Geometronics Unit, Oregon DOT – Operating the Oregon Real-time GPS Network Oregon State University – Dan Gillins, Assistant Professor, PhD, PLS

Submitted abstract to ION for GNSS+ 2014 Conference

– Michael Eddy: graduate thesis Processing long static baselines w/ and w/o

GLONASS You ??– Any white papers, statistically valid tests, etc. would

be appreciated.

Issues with GLONASSIssues with GLONASS Time tags and receiver clock offsets: GPS time

vs GLONASS time Reference datum offsets from GPS (WGS84) to GLONASS (PZ-90.02) GLONASS FDMA format vs the CDMA format for

GPS and Galileo New Russian K satellites are CDMA

– Different manufacturers have different, usually proprietary, solutions for handling these biases

Issues with GLONASSIssues with GLONASS Very limited GLONASS tracking/monitoring

network worldwide; mostly within Russia– Russia plans to add world wide tracking stations– Current political situation could inhibit

GPS/Galileo cooperation with GLONASS No GLONASS plan for new signal in L5 Band– L5 is a Safey-of-Life protected frequency– L5 is supported by GPS, Galileo and Beidou

Russian GLONASS/GNSS Forum’s Questionairre http://aggf.ru/pr.php?nn=5375

“4. Является ли важным с точки зрения конкурентоспособности, чтобы КА системы ГЛОНАСС, в дополнение к запланированным новым кодовым сигналам в традиционных диапазонах ГЛОНАСС (L1, L2, L3) передавали бы еще и сигнал в диапазоне L5? Почему? Если да, то для каких потребителей это важно?”

As reported on-line by in GPS World magazine:http://gpsworld.com/survey-seeks-suggestions-on-future-of-glonass

Russian GLONASS/GNSS Forum’s Questionairre http://aggf.ru/pr.php?nn=5375

“4. Is it important in terms of competitiveness, for the GLONASS satellites, in addition to the planned new code signals in the traditional GLONASS bands (L1, L2, L3) to add another signal in the range L5? Why? If yes, for which consumers is this important?”

As reported on-line by in GPS World magazine:http://gpsworld.com/survey-seeks-suggestions-on-future-of-glonass

and translated by Richard Langley, Innovations Editor for GPS World:

Issues with GLONASSIssues with GLONASS

Availability of real-time precise ephemerides for GLONASS?

Oregon Real-time GPS Network software automatically downloads the predicted half of the Ultra-Rapid ephemerides four times daily and incorporates them into our network (multi-base) real-time correctors.

Will real-time precise GLONASS ephemerides be available for RTNs ???

IGS MGEX (Multi GNSS Experiment)http://igs.org/mgex/ The Multi-GNSS Experiment (MGEX) has been set-up by the

International GNSS Service (IGS) to track, collate and analyze all available GNSS signals. This includes signals from the BeiDou, Galileo and QZSS systems, as well as from modernized GPS and GLONASS satellites and any space-based augmentation system (SBAS) of interest.

Analysis centers will attempt to estimate inter-system calibration biases, compare equipment performance and further develop processing software capable of handling multiple GNSS observation data.

The development of multi-GNSS IGS products.

Planning for testingPlanning for testing Letters to manufacturersLetters to manufacturers

– How do their products use GLONASS in RTK and postprocessing.

– Supplemental to GPS or equal to GPS Investigate prior research

– White papers– ION GNSS presentation archives– E-mail: Dan Gillins, OSU, to Dr Neil

Weston, Deputy Director, NGS

E-mail: Dr Neil Weston, Deputy Director, NGS,to Dan Gillins, OSU

– NGS has not done too much with respect to GPS +GLONASS processing

– NGS has spent a few months looking at the Pages software (NGS) to see how GLONASS can be incorporated

– NGS hopes to add GLONASS (to their products such as OPUS) and also focus on Galileo

– With respect to helping out with a study, NGS cannot offer too much other than CORS data with GPS+GLONASS.  

– Do you have more specific ideas in mind?

NGS testing and evaluation of GLONASS would help real-time network administrators and also surveyors in general

Planning for TestingPlanning for Testing Perform enough test repetitions to yield Perform enough test repetitions to yield

statistically valid results.statistically valid results. Publish accuracy analysis at the 95% Publish accuracy analysis at the 95%

confidence level per FGDC Geospatial confidence level per FGDC Geospatial Positioning Accuracy Standards.Positioning Accuracy Standards.– http://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/   

Planning for testingPlanning for testingTesting in open, medium, and heavy Testing in open, medium, and heavy canopy.canopy.

Establish accurate test networks in Establish accurate test networks in canopy with total station network tied to canopy with total station network tied to accurate static GPS sites in open canopy.accurate static GPS sites in open canopy.

US Forest Service Clackamas GPS Test NetworkUS Forest Service Clackamas GPS Test NetworkMt. Hood National ForestMt. Hood National Forest

US Forest Service Clackamas GPS Test NetworkUS Forest Service Clackamas GPS Test NetworkMt. Hood National ForestMt. Hood National Forest

US Forest Service Clackamas GPS Test NetworkUS Forest Service Clackamas GPS Test NetworkMt. Hood National ForestMt. Hood National Forest

Issues with testingIssues with testing Testing can’t cover all brands of GPS receivers Different GPS RTN softwares handle GLONASS differently As GNSS constellations change, ongoing testing will be

needed– GPS new CNAV Signals, ie. L5 stronger signal strength is supposed to

help in canopy.– GLONASS: CDMA?, L5?, worldwide tracking/monitoring?– BEIDOU: coming on strong?– Galileo: just around the corner?

Manufacturers will adopt new and better processing algorithms to better take advantage of various GNSS

All these changes will point out the need for ongoing testing.– Test networks with accurately positioned marks will continue to be

valuable.

Oregon Real-time GPS Networkwww.TheORGN.net

ORGN@odot.state.or.usThe beach at Bandon, Oregon