Considerations for Testing GLONASS

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Considerations for Testing GLONASS
Mount Hood, Oregon Photo by Daryl
Moistner www.nevadasurveyor.com

• Ken Bays, PLS
• Lead Geodetic Surveyor, Oregon DOT
• NGS Best Practices for RTN Administration
  Webinar
• 20 March 2014

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Oregon Real-time GPS Networksince 2006
Ken Bays, Lead Geodetic Surveyor Randy Oberg,
Geodetic Surveyor
GPS Antenna Cable
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Overview

• Why test GLONASS?
• What do we want to test?
• Who is involved in the testing?
• Issues with GLONASS
• Planning for testing
• Issues with testing

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Why 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

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What 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 wont yield a solution?

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What 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.

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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.

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Issues 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

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Issues 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

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Russian GLONASS/GNSS Forums Questionairre
http//aggf.ru/pr.php?nn5375
As reported on-line by in GPS World
magazine http//gpsworld.com/survey-seeks-suggest
ions-on-future-of-glonass

• 4. ???????? ?? ?????? ? ????? ??????
  ?????????????????????, ????? ?? ??????? ???????,
  ? ?????????? ? ??????????????? ????? ???????
  ???????? ? ???????????? ?????????? ??????? (L1,
  L2, L3) ?????????? ?? ??? ? ?????? ? ?????????
  L5? ??????? ???? ??, ?? ??? ????? ????????????
  ??? ??????

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Russian GLONASS/GNSS Forums Questionairre
http//aggf.ru/pr.php?nn5375
As reported on-line by in GPS World
magazine http//gpsworld.com/survey-seeks-suggest
ions-on-future-of-glonass and translated by
Richard Langley, Innovations Editor for GPS
World

• 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?

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Issues with GLONASS

• Availability of real-time precise ephemerides for
  GLONASS?

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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 ???
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IGS MGEX (Multi GNSS Experiment)http//igs.org/mg
ex/

• 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.

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Planning for testing

• Letters 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

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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
  GPSGLONASS.  
• Do you have more specific ideas in mind?

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

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Planning for Testing

• Perform enough test repetitions to yield
  statistically valid results.
• Publish accuracy analysis at the 95 confidence
  level per FGDC Geospatial Positioning Accuracy
  Standards.
• http//www.fgdc.gov/standards/projects/FGDC-standa
  rds-projects/accuracy/   

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Planning for testing

• Testing in open, medium, and heavy canopy.
• Establish accurate test networks in canopy with
  total station network tied to accurate static GPS
  sites in open canopy.

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US Forest Service Clackamas GPS Test NetworkMt.
Hood National Forest
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US Forest Service Clackamas GPS Test NetworkMt.
Hood National Forest
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US Forest Service Clackamas GPS Test NetworkMt.
Hood National Forest
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Issues with testing

• Testing cant 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.

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Oregon Real-time GPS Network www.TheORGN.net ORGN_at_
odot.state.or.us
The beach at Bandon, Oregon