Future IGS & inter-technique SINEX combinations: Issues and challenges
D. Lavallee, R. Ferland, D. Thaller, T. Herring.


Recommendations relating to Internal IGS Activities
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COMBI-1: Define and maintain IGS conventions/procedure/guidelines
document

COMBI-2: Use agreed set of models (currently IERS 2003)
Essential  for both internal (GNSS) and external (other services, IERS)
product interface. Recommend that SINEX files detail applied models and
procedure. A SINEX block could be defined specifically to include this
information.

COMBI-3: Report all apriori constraints, ensure they are removable
Unconstrained solutions are preferred. Loose (2-3 order of magnitude
than the estimates uncertainty) may be used. Inner (origin, orientation,
scale) constraints acceptable.

COMBI-4: Minimize equipment changes due to GNSS modernisation
The modernization should be coordinated to minimize equipment changes.
Multiple receivers and antennas should be used in parallel at core
sites, there should be a clear procedure for handling the processing in
these cases.

COMBI-5: Mechanism to contribute and share station discontinuity
information 
All users of station coordinates time series can potentially contribute
to and benefit from this.


Recommendations relating to External Activities (IERS and others)
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COMBI-6: Include troposphere parameters in the SINEX files
Natural extension to the existing coordinates parameters, to which they
are correlated. They can be combined with estimated troposphere from
other techniques such as VLBI and DORIS to good effect. This should be
done in conjunction with an upgrade to SINEX Version 2.x

COMBI-7: Provide rapid combined IGS SINEX Product
Include a selected set of stations (important: Wettzell, Kokee Park,
Tsukuba) and pole positions to help to improve VLBI UT rapid solution.

COMBI-8: Provide mechanism to stream extended products for
inter-technique combinations via IGS
Where IGS AC's can provide extended products (e.g. daily sinex, or
normal equations of extended parameterisations)  for inter-technique
combinations, AND these products are directly related to the IGS
products, that these products are streamed via IGS