AUSLIG Online GPS Processing Service (AUSPOS)

John Dawson, Ramesh Govind, John Manning

Concepts – AUSPOS Background – How it works

Local Survey Mark

New Survey Marks

Geodetic Survey Mark

Local Survey Mark

STEP 1

STEP 2

www.auslig.gov.au

GPS data via Internet

New Survey Marks Local Survey Mark

STEP 1

What is AUSPOS?

– Internet web application– users submit geodetic quality GPS via web-browser– rapid turn-around precise positions via email– cm level coordinates anywhere in the World!

• including Antarctica– position quality depends on data quantity/quality– local datum within Australia (GDA94)– ITRF coordinates outside of Australia – FREE service

What do you Need?– GPS data

• dual frequency data• > 6 hrs of continuous

– Internet web browser• i.e. netscape, Internet Explorer

– Email address

UserGPS Data

Processing ResultsCoordinates (email)

What do you Submit?

– GPS data (RINEX)– Your email address– the height of your GPS antenna– the type of your GPS antenna

} height

Speed and accuracy

• 6 hour data file• results delivered in ~ 3 minutes• 20 mm horizontal, 50 mm vertical

• 24 hour data file• results delivered in ~15 minutes• <10 mm horizontal and 10-20 mm vertical

How it works• International GPS Service (IGS)

• worldwide network of permanent GPS receivers• ‘baseline’ from three closest GPS• station to station distances

• Antarctica -- typically 1000 km to 3500 km

IGS

IGS

IGS

User GPS

International GPS Service (IGS) Permanent GPS

AUSPOS, GPS Errors and Models• state-of-the-art processing system (MicroCosm)

IERS96 conventions• orbit error

uses IGS precise orbits• receiver and satellite clock error

eliminated by double difference• troposphere refraction

scale factor estimated• ionospheric refraction

dual frequency observations• antenna phase centre variations

uses IGS phase centre models

AUSPOS Accuracy versus Observation Length

AUSPOS Applications DGPS reference station positioning Remote GPS station positioning Ultra-long GPS baseline positioning GPS connections to IGS and ARGN stations High accuracy vertical GPS positioning In the field high-accuracy processing GPS network quality control

AUSPOS Australian Users

AUSPOS Global Users

AUSPOS Applications in the Antarctic

• provides access to high-accuracy GPS processing

• free and easy to use

• high level ITRF geodetic control

• remote Antarctic locations

• single GPS receiver

AUSPOS Email

AUSPOS Report

Useful Internet GPS Resources

AUSLIG home page www.auslig.gov.au

AUSLIG Geodesy home page www.auslig.gov.au/geodesy/newhome.htm

AUSPOS home page www.auslig.gov.au/geodesy/sgc/wwwgps/wwwgps.htm

IGS home page igscb.jpl.nasa.gov