# Presentation: 760144

## ESOC Combined GNSS Processing

_**T. Springer**_**, F. Dilssner, E. Schoenemann, **
**I. Romero, J. Tegedor, F. Pereira, J. Dow**

## Motivation

**Motivation**

- IGS = International _**GNSS**_ Service => not only GPS!
- Called GNSS Service since 2005!
- ...but...IGS network is far from being a GNSS tracking network!
- GLONASS is going towards full constellation by 2009
- End of 2008 possibly 22 satellites
- Galileo is coming!
- First two test satellites are flying (GIOVE-A and GIOVE-B)
- Global tacking network available (13 GESS)
- New and better signals!
- Compass developments!?
- Additional GPS satellite provide some benefits
- Additional other GNSS satellites with different orbit characteristics' may provide even more benefits (ERPs, Geocenter, yearly “signals”)
_***but***_ biases between different GNSS systems may obscure the potential benefits

## Giove-A versus GPS Signal Quality

**Giove-A versus GPS Signal Quality**

## GESS (GIOVE) Tracking Network

## IGS GNSS Tracking Network

**Almost no US nor Canadian GNSS Stations!**

##  G17 |************************************************************************
 G12 |************************************************************************
 G15 |************************************************************************
 G29 |************************************************************************
 G07 |************************************************************************
 ----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|-- 

** ****G12 |**************************************************************************
** ****G15 |**************************************************************************
** ****G29 |**************************************************************************
** ****G07 |**************************************************************************
** ****----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|-- **

**Pseudo Graphics of GNSS Tracking**

** ****E01 |-344444444433-222--33344555555555665533344433333334444456666566666667776**
** ****E16 |344455556655555666665444445443224444444445555544456777555554344335555554**
** ****----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|--**
** ****Timestep per interval (sec) : 1200**

** ****R04 |2345444444444449*******************65788887998778989**77********96556465**
** ****R06 |***976456666799998666655777******************34445768889999***************
** ****R08 |*************9*-9**889*888887744344568*-************9545544456788858******
** ****R10 |998878**************95553355677554555455*******************7568*98889*98**
** **_**R11**_** |22334444557788*********9--21122433333233333667******************6332333-**
** **_**R13**_** |*****554433343455559************---4332223343333233-55-689****************
** ****R14 |********754555445546668*******************988898*9999665565669************
** **_**R15**_** |7**********7763333322332236***************98885553343333333422124459******
** **_**R17**_** |565-*****************-2222323333-467779********95------333333233333668*-**
** ****R19 |9*999855466669***************6666455667**96*************88*98897799*9998**
** ****R20 |788**99999999422579*************765555445546668*******************9889*9**
** ****R23 |************566998879**88889*************976676765554445666***************
** ****R24 |*****************5544788999878**************965433556887555555558******* **
** ****----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|-- **

## GPS – Giove-A Combined Analysis

**GPS – Giove-A Combined Analysis**

- Giove-A Microwave Analysis (150 days)
- IGS final orbits and clocks fixed
- Estimated parameters
- Giove-A orbit and clock
- GESS station coordinates and clocks
- Receiver dependent bias between GPS and Giove-A
- Daily solutions saving the normal equations
- Generate n-day solution based on normal equations (n = 1, 2, 3, 4, and 5)
- Giove-A Combined Microwave and SLR Analysis
- Repeat analysis above but now including all SLR observations from the Giove-A satellite.
- Validation Analysis
- Repeat the analysis above but in addition treat one of the GPS satellites in the same way as the Giove-A satellite

## Giove-A versus GPS Orbit Quality

**IGS 2-day Orbit Overlap RMS = 11 mm**

**Glonass 2-day Orbit Overlap RMS = 173 mm **

## Giove-A: Receiver Intersystem Bias

**Orbit Quality surprisingly good given the poor quality of the tracking network!**

## BAHN Intersystem Bias estimation – R04

**LEICA**

**TRIMBLE**

**JPS**

**TPS**

## Conclusions

- The IGS is currently mainly a GPS-only service!
- No reasonable GNSS tracking network
- No GNSS product with “IGS label”
- But...two ACs (CODE and ESOC) provide true combined GNSS solutions
- Several formats do (still) not cater for GLONASS let alone GALILEO, especially in the real time area!
- To become a true GNSS service IGS will have to:
- Enforce that all (new) IGS stations are GNSS stations
- Start generating a true GNSS combined product (orbit and clock)
- Ensure that all formats are GNSS capable
- Should start ASAP!
- Significant interest and demand exists for GNSS products!

**To GPS or to GNSS that is the question!**

## Thank You!