The document discusses improving the open-source goGPS project, which provides Java and MATLAB implementations for real-time and post-processing GPS positioning using low-cost receivers. It summarizes recent updates, including the first official Java release, support for additional receivers and dynamic models, multi-receiver logging, and testing showing positioning accuracy of 20-80cm using single-frequency data. Future developments discussed include improving positioning algorithms, integrating motion sensors, and making goGPS available as a web service.

1. Improving goGPS:
Java implementation,
web applications and add-ons
FOSS4G 2011 Osaka

2. GPS receivers for navigation
(i.e. kinematic positioning)
Double frequency Single frequency Single frequency low-cost
geodetic receivers professional receivers (consumer-level) receivers
US $ 10000 - 30000 US $ 1000 - 2000 US $ 50 - 200
2-3 cm 15-30 cm 3-5 m
RTK DGPS / stand-alone
(L1+L2) RTK (L1)
40 cm - 80 cm
goGPS raw data!
single-frequency RTK

3. Relative positioning (double differences)
GPS error budget:
- orbit error (ephemeris): negligible
- satellite and receiver clock errors: negligible
- ionosphere and troposphere effects: negligible if D<10 km
- signal degradation
- hardware quality
Master receiver Rover receiver
(known position) D

4. goGPS MATLAB
- developed in MATLAB 7.6+ - Real-time and post-processing
- GUIs available - works on both Windows and UNIX

5. goGPS Java
- client/server architecture - Real-time and post-processing
- GUI not yet available - platform independent
- faster than goGPS MATLAB

6. goGPS Java first official release
(two days ago!)
http://www.gogps-project.org

7. Collaborative environment
MATLAB Java
http://sourceforge.net/projects/gogps/ http://code.google.com/p/gogps/
SVN Mercurial

8. goGPS international network
(as of November 2011)
SBB
http://www.sbb.ch (GNSS positioning services)
Cryms
http://www.cryms.com
Universidad de Jaén
http://www.ujaen.es
Applied Technology
goGPS http://www.apptec.co.jp
Polytechnic of Milan
http://www.polimi.it OSGEO JP
http://www.osgeo.jp
gRED Tezukayama Gakuin University
http://www.tezuka-gu.ac.jp/
Galileian Plus
http://www.galileianplus.it Osaka City University
Volunteers http://www.osaka-cu.ac.jp
(open source)
FISI
http://www.fisi.org

9. Post-processing

10. Real-time processing

11. Accuracy test
(December 2010)
Accuracy tests with receivers mounted on a car driven at different speeds with
good sky visibility condition.
Position known with few
centimeters of error (RMS < 2 cm)
goGPS positioning using single frequency
raw data: TOPCON double
frequency receivers
- with TOPCON receivers → RMS 20 ~ 40 cm
- with u-blox receiver → RMS 40 ~ 80 cm u-blox receiver

12. Kinematic positioning
Receiver: u-blox AEK-4T
goGPS solution
- RTK (VRS)
- Dynamical model (const vel.)
- Observations weighted on SNR
u-blox solution
- Stand-alone
- Pedestrian dynamical model
2D translation: ~2m

13. Static positioning
u-blox+goGPS solution
compared with static
positioning by double
frequency receiver:
~ 30 cm

14. Low-cost receivers supported by goGPS
(as of November 2011)
Fastrax IT03 u-blox 4T / 5T / 6T SkyTraq S1315F-RAW

15. Multi-receiver logging
(since version 0.2.0beta)
REC. 1 RINEX 1
goGPS
REC. 2 RINEX 2
REC. 3 RINEX 3

16. Multi-receiver test

17. Variable dynamic model
(since version 0.2.0beta)
static
goGPS Kalman filter dynamic model constant velocity
constant acceleration
BEFORE v0.2.0beta same dynamic model for
each processing session
SINCE v0.2.0beta the user can switch between different
dynamic models during the survey

18. Variable dynamic model

20. goGPS as a web service
goGPS can provide GPS data processing as a web
processing service (WPS) to obtain accurate positioning
from raw GPS observations
accurate positioning
(e.g. KML file)
raw observations
(e.g. RINEX files)
Server providing Raw data loggers
goGPS as WPS
(ZOO WPS engine)
http://localhost/cgi-bin/zoo_loader.cgi?metapath=
ServiceProvider=zgoGPSService=WPSRequest=Execute
Version=1.0.0Identifier=goGPSDataInputs=Obs=rover.11o;
Nav=rover.11n;mObs=master.11o

21. goGPS processing by grid computing
(Oracle GridEngine)
Scalability test for goGPS Java
server-side processing with
concurrent requests (Yoshida,
2011)

22. goGPS for road mapping
Accurate path maps with low-cost GPS receivers, goGPS tracks can be used for
integrating the output into a web-GIS OpenStreetMap

23. Polyline simplification
(goGPS MATLAB tool)

24. goGPS for surveying
Archeological surveying with a
required accuracy of the order
of ~50 cm
goGPS + + VRS (or closest station)
RTK – L1 only

25. Swiss Federal Railways SMART project
measuring geographic areas by means of low-cost RTK positioning
raw data collector client-side
goGPS Java processing server-side
Swisstopo VRS

26. Swiss Federal Railways SMART project
Server-side processing environment
(courtesy of CRYMS Sagl)
eZe2 device Server unix based Swiss Federal
Board M2M/ Tomcat 6.0 Railways
custom Eriadne Server
Cinterion TC65i goGPS service SAP
uBlox 5T
Display
Keyboard
Swisstopo uBlox
Master VRS Navigation
Ephemeris
only logging raw data!

27. Swiss Federal Railways SMART project
Server-side monitor
control interface
(courtesy of CRYMS Sagl)

28. Swiss Federal Railways SMART project
Precision test
(courtesy of CRYMS Sagl)

29. Swiss Federal Railways SMART project
measuring geographic areas by means of low-cost RTK positioning
Testing the system
performance
(photos courtesy of CRYMS Sagl
and Politecnico di Milano,
Geomatics Laboratory)

30. Future developments
1) Improvement of positioning algorithms, focusing on post-
processing; additional receiver support; other satellite systems
(QZSS, Compass, GLONASS, Galileo, EGNOS, MSAS)
2) Motion sensors integration (accelerometers, gyros, odometer, )
→ hardware prototype
3) goGPS Java made available as an application (command line /
GUI)
4) goGPS processing made publicly available as a web service