[IGSMAIL-5835]: ESOC Analysis Changes

[Tim.Springer at esa.int]

******************************************************************************
IGS Electronic Mail      26 Sep 08:43:00 PDT 2008      Message Number 5835
******************************************************************************

Author: Tim Springer


Dear IGS Colleagues,

In the last two weeks we have made a couple of small changes to our IGS 
Final analysis.

One change is that  we switched to a new release of our Napeos software 
which we call version 3.1. 
Amongst others, this version enables us a better handling of the biases 
observed between the GPS and GLONASS observations in the GNSS receivers. 
We can now export the estimated biases to our normal equations and stack 
them over the full week and consequently eliminate them before generating 
our SINEX file. In this way we are now able to generate a proper GNSS 
SINEX file which can be used in the IGS SINEX combination.

A second change is that starting with this weeks submission we have added 
a large set of non-IGS, but GNSS(!!), stations to our processing. We were 
"forced" to include these non-IGS sites because the IGS tracking network 
provides very poor tracking of the GLONASS satellites and this has a 
significant (negative!!) impact on our products. The added GNSS stations 
are locations where the IGS network provides very little, or even no, GNSS 
tracking. Amongst these stations are 8 CORS stations, many thanks to 
Giovanni Sella for making them available and to our BKG colleagues for 
downloading the data and making it available on their GLONASS data 
archive. These CORS stations significantly improve the GLONASS tracking 
over North-America. An other important addition are a set of 7 Brasilian 
stations. These stations are in the process of becoming IGS stations and 
should soon be. Again, we are able to access this data thanks to our BKG 
colleagues who are generating the data of these stations from their 
real-time NTRIP streams. In order to not "drop" any IGS reference frame 
stations we increased the number of stations in our processing from 100 to 
110.

Starting with the submission of this week we now submit a complete set of 
GNSS products, i.e., orbits, clocks, summary, but also the clock and sinex 
files are now submitted to the IGS data centers. It is our intention that 
within the next couple of weeks we will terminate our GPS-only solution 
and only produce and submit our true GNSS products to the IGS (we will of 
course coordinate and test this change with the different combination 
centers before going "life" with it). The users of the ESOC products are 
advised the have a look at our "esx" line of products to see if your 
software is able to ingest these GNSS solutions!

With the launch of 3 new GLONASS satellites yesterday and 3 more scheduled 
for launch in December the GLONASS constellation is nearing FOC status. We 
hope that the IGS network follows this GLONASS evolution by putting up 
more GNSS sites, since there are still significant "holes" in the GLONASS 
part of the IGS tracking network.

Many greetings,
Tim Springer

---------------------
Tim Springer
Navigation Support Office, OPS-GN (nng.esoc.esa.de)
European Space Operations Centre
Robert Bosch Strasse 5
64293 Darmstadt
Germany
Tel: +49-6151-90-2029  Fax: +49-6151-90-3129