Date: Thu, 4 Apr 2002 13:28:58 -0800
From: Pascal Willis <Pascal.R.Willis@jpl.nasa.gov>
To: jean-paul.berthias@cnes.fr
Cc: ries@sol.csr.utexas.edu, bjh@cobra.jpl.nasa.gov, feissel@ensg.ign.fr,
    Carey Noll <carey.noll@gsfc.nasa.gov>, frank.lemoine@gsfc.nasa.gov,
    nerem@colorado.edu, nzelensk@geodesy.gsfc.nasa.gov,
    krchoi@csr.utexas.edu, Gilles.Tavernier@cnes.fr, yeb@cobra.jpl.nasa.gov,
    wib@cobra.jpl.nasa.gov, werner.gurtner@aiub.unibe.ch,
    dxk@cobra.jpl.nasa.gov, Jean-Jacques Valette <jvalette@priam.cls.fr>,
    jean-pierre.granier@cnes.fr
Subject: Please change DORIS/SPOT preprocessing and DORIS/CDDIS files

Dear Jean-Paul,

here is the synthesis of what we did here concerning multiple
DORIS satellite orbits determination in the same filter run:

	1) before Jan 15, 2002 (SPOT2, SPOT3, SPOT4, TOPEX)
	data can be processed but the inconsistent preprocessing (removing of
	constant biases per pass instead of removing a daily clcok polynomial
	for the satellites) impose to reject data with common passes 
on the same
	stations for 2 satellites. Fortunately, this does not happen
	very often without the tandem phase of JASON
	As it would be an tremendous work to preprocess all the existing data,
	I think it is now wise to wait for really raw DORIS data and live
	with the actual DORIS/DATA at CDDIS before Jan 15 (start of JASON
	cycle 1)

	2.1)after Jan 15, 2002 (TOPEX and JASON only)

	data posted at CDDIS can not be processed (see my previous emails)

	data posted at AVISO can be processed properly. Everything works
	fine with TOPEX and JASON

	2.2)after Jan 15, 2002 (TOPEX, JASON, SPOT4 and soon SPOT2)

	data posted at CDDIS can not be processed (see my previous emails)

	data posted at AVISO cannot be processed as the SPOT data are not
	preprocessed using the same strategy. Please send a first SPOT file
	at AVISO to verify that everything works fine.

In conclusion, I suggest that you give to CDDIS the existing correct
DORIS data for TOPEX and JASON and that you resubmit data for SPOT4
(and soon for SPOT2) using the new preprocessing strategy, maybe starting
with a first cycle at AVISO for test purposes.

Thanks in advance for your efforts
Pascal