• General for all techniques:
  -    time series analysis and identification of discontinuities and outliers
  -    correction for atmospheric and hydrological loading on NEQ level before accumulation   
• GPS: set-up of 7 Helmert parameters per day         
• DORIS: set-up of 7 Helmert parameters per week
• Accumulation of NEQ time series and estimation of one TRF solution per technique:
  -    consideration of identified discontinuities and outliers

Combination of the techniques: 

• Selection of local ties
• Selection of velocities to be combined
• Comparisons / combination of EOP (all available EOPs are considered):
  -    pole coordinates: combination of all techniques         
  -    pole rate: combination of GPS and VLBI
  -    LOD: combination of GPS, VLBI and SLR, even if SLR series shows significant frequencies w.r.t. GPS and VLBI but also higher standard deviations (factor 20)
  -    UT1: VLBI only
  -    nutation (X,Y): VLBI only
  
  Table of combined parameters
   

• Technique	Station coordinates	Pole coordinates	Pole rates	LOD	UT1	X	Y
  GPS	x	x	x	x
  VLBI	x	x	x	x	x	x	x
  SLR	x	x		x
  DORIS	x	x
  DTRF2014	x	x	x	x	x	x	x

   

• Datum realization:

  - origin: SLR only

  - scale: weighted mean of VLBI and SLR (scale differences are not significant)             

  - orientation: no-net-rotation w.r.t. DTRF2008 (GPS stations only)