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Questionnaire concerning GLONASS biases:
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Your institution: CODE
Contact email address(es): code@aiub.unibe.ch

The GLONASS clock corrections you generate are consistent to:
[X] pseudorange
[X] carrier phase
Please mark both fields if indicated.

Clock corrections are generated at intervals of: 30 sec
- clock estimation at intervals of 5 min
- phase-based interpolation at intervals of 30 min

Handling of GLONASS interfrequency code biases (for ionosphere-free LC):
[X] one bias parameter for each station and satellite combination/pair
[X] one bias parameter for each station and frequency channel combination/pair
[ ] other configuration:
Remark: first setup is commonly used (for operational analysis)
Time resolution: 1 set of biases per day (24 hours)

Description of datum definition (or reference) for GLONASS code biases:
Zero-mean conditions with respect to:
- all biases belonging to a particular GLONASS satellite (n_sat_glo conditions)
- all biases (1 condition)

How many conditions/constraints are imposed for the bias datum definition?
n_sat_glo + 1

How do you select GLONASS code observable types (to be used for a specific
station) if P1 and C1, or P2 and C2 are available?
- P1 selected if both P1 and C1 available (but C1 if P1 unavailable for GPS)
- C2 not yet used (for operational analysis)
Remark: C2 is used for P2-C2 DCB estimation

Do you generate GLONASS clock corrections on a regular/operational basis?
[X] Yes
[ } No, but test results (in clock-RINEX) would be available for:
Note: Corresponding results available starting with year 2008 (at request)

Recommendations for PPP users of your GLONASS clock product:
- Consideration of corresponding bias parameter setup (see above)
  if pseudorange is used
- None in case of phase only

Do you have corresponding GLONASS bias results available (in ASCII form)?
[X] Yes
[ ] No

Are there any specialties concerning your GLONASS clock product?
- High-rate corrections available (at intervals of 30 sec)
- GLONASS biases are generated for more stations than used for actual
  GNSS clock estimation
- GLONASS biases are extracted regularly in both modes (sat- and
  freq-specific) using full NEQ information
- Generally all active satellites are considered (including unusable sats)

Extra question: Do you have experience with GLONASS ambiguity resolution?
[ ] No
[X] Yes, please specify:

  Ambiguity resolution extended to GLONASS for the following resolution
  strategies (performed for baselines up to 20/200/2000 km length):
  - Direct L1/L2 GPS/GLONASS ambiguity resolution without any restriction
    (with SD bias retrieval).
  - Phase-based widelane/narrowlane GPS/GLONASS ambiguity resolution without
    any restriction (with SD bias retrieval and subsequent introduction for
    narrowlane resolution).
  - GNSS Quasi-Ionosphere-Free (QIF) strategy with a restriction of GLONASS
    ambiguities to identical frequency channel numbers.
  - No corresponding attempt is made for the pseudorange-based widelane
    resolution strategy (performed for baselines up to 6000 km length).
  Note: GPS-GLONASS intersystem ambiguities are generally treated
  unresolved.

  See also IGS Report message no. 19560:
  http://igscb.jpl.nasa.gov/pipermail/igsreport/2011-March/019573.html

  Development of GNSS-capable LAMBDA ambiguity resolution:
  http://www.swisstopo.admin.ch/swisstopo/geodesy/pnac/presentations/EUREF2009_Paper_Rapid_Static_GNSS_Schaer.pdf


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