Permanent GNSS Stations(GNSS – Global Navigation Satellite System)

Dionyssos Satellite Observatory

Must

• Monument stability

• Obstacle free

• Interference free

• Data Streaming capability

Dionyssos Satellite Observatory

Main Public Organizations

• IGS : International GNSS Servicehttp://www.igs.org/

• EUREF : European Geodetic Reference Systemshttp://www.euref.eu/

Dionyssos Satellite Observatory

EUREF GNSS Network

Dionyssos Satellite Observatory

EUREF in Greece

NTUA DSO

NOA

AUTH

INSU

TUC

Dionyssos Satellite Observatory

Station (DYNG) at Dionyssos Satellite Observatory (NTUA-CNES)

Trimble Net R9

Installed at May 2011

IGS, EUREF, REGINA networks

https://space-geodesy.nasa.gov/docs/2011/02_REGINAhostingsitev1_en.pdf

http://itrf.ensg.ign.fr/doc_ITRF/RT121_POYARD_DionysosITRFCo-locationSurvey.pdf

Dionyssos Satellite Observatory

Dionyssos Satellite Observatory

NTRIPprotocol for streaming GPS data over the Internet

• NTRIP : Networked Transport of RTCM via Internet Protocol

RTCM : Radio Technical Commission for Maritime Services

developed by the German Federal Agency for Cartography and Geodesy (BKG) and the Dortmund University Department of Computer Science

- GNSS Data segmentCollecting & streaming GNNS data

- SSR (Space State Representation) segmentComputing & streaming SSR (ephemeris/clock corrections)

!!!! REAL TIME !!!!

Dionyssos Satellite Observatory

NTRIP modules

Dionyssos Satellite Observatory

NTRIP modules

Dionyssos Satellite Observatory

EUREF CASTERReal-Time GNSS Data Streams From EUREF-IP Ntrip Broadcaster

www.euref-ip.net:2101

Dionyssos Satellite Observatory

IGS CASTERReal Time SSR (Ephemeris/clock corrections) streaming table

products.igs-ip.net:2101

Dionyssos Satellite Observatory

1 or 2 receivers ?

Dionyssos Satellite Observatory

Positioning Techniques

• Single : One receiver, acc. 2-30m

• Relative : 2 Receivers

Static acc. < 1-2 cm

DGPS acc. < 1m

Kinematic acc. < 5cm fixed , < 20cm float

• PPP : One receiver (SSR input), acc. <10cm

NTRIP

Dionyssos Satellite Observatory

RTK vs. PPP

• RTK: “Tell me the precise location of your reference station and I will tell you the precise location of your mobile receiver.”

• PPP: ”Tell me the precise location of the navigation satellites and I will tell you the precise location of your mobile receiver.”

Static (with precise orbits) does both !

Dionyssos Satellite Observatory

PPP procedure

Dionyssos Satellite Observatory

Mainly used Ntrip software(open source)

• BNC https://igs.bkg.bund.de/index/index

pros : extremely accurate PPP

cons : only PPP, not so user friendly

• RTKLib http://www.rtklib.com/pros : user friendly environment, DGPS, RTK,PPP

cons : not so accurate real time PPP

Dionyssos Satellite Observatory

Other Links

• PPP-Wizard project

http://www.ppp-wizard.net/index.html

• Orbits & Clock corrections

https://igs.bkg.bund.de/ntrip/orbits

Dionyssos Satellite Observatory

BNC PPP in progressStation LAMY (Lambadario)

Dionyssos Satellite Observatory