influence of using individual gps receiver antenna
TRANSCRIPT
Influence of using individual GPS receiver antenna calibrations
on high precision geodetic positioning, case study: Northern
Surat Basin Queensland 2015 GPS campaign
IGNSS 2016, Sydney, 6 – 8 December 2016
Guorong Hu & Michael Moore
Geodesy Section, Geoscience Australia
GNSS antenna types
GNSS antenna
Satellite antenna
Block I Block II, IIA, ….
Receiver antenna
Single frequency (mobile phone, low cost GNSS
receiver antenna)
Dual frequency (high precision
geodetic receiver antenna)
Basic concepts
ARP (Antenna Reference Point)
GNSS satellite
antenna
Zenith
Mean Phase Centre
PCO: Phase Centre Offset, given in NEU components relative to the ARP
PCV: Phase Centre Variation, variation of the actual phase centre with the direction of
the arrival of the signal, provided as a function of elevation angle and/or azimuth angle
in antenna frame
NRP: North Reference Point, the NRP should be properly oriented to true north for
antenna calibration
GNSS receiver
antenna
Relative calibration: Phase centre determinations from a
stationary test pier referenced to a standard (Dorne Margolin
choke ring antenna, type T: AOAD/M_T)
Absolute calibration: calibration where PCO/PCV are
independent of the reference antenna
Individual calibration: calibration values which are specific
to the antenna serial number
IGS type mean calibration: calibration values for an antenna
model, where several test samples are separately calibrated
and averaged together by IGS antenna working group
GA type mean calibration ……
Basic concepts
Relative antenna calibration: 30 June 1996 ~ Nov. 2006
Absolute antenna calibration: Nov. 2006 ~ present
Calibration facilities officially recognized by IGS:
GA, Geo++, NGS, Univ. Hannover, Univ. Bonn
GA was recognized/approved by IGS antenna working group
announced in IGS workshop 2016 in Sydney, Feb 2016
History of antenna calibration of IGS products
Systematic errors caused by assumptions of relative PCVs:
PCV(AOAD/M_T)=0 & PCV(GNSS sat. antenna)=0
Why relative PCVs to absolute PCVs
Independent from reference antenna
High resolution and precision PCVs
Site and location independent
Advantages of absolute antenna calibration
Two absolute calibration methods:
Anechoic chamber calibration: using
artificial GPS signals
Robotic calibration: using real GPS
signals
Absolute GNSS antenna calibration method
Credit: University of Bonn
GA’s robotic ACF
Impact on GPS solutions including:
Terrestrial scale (global solutions)
Station coordinates
Orbit parameters
Troposphere parameters
Why antenna calibration matter
Findings of experiment by IGS Antenna WG on reprocessed
global solutions of ~ 200 stations data from 1994 to 2005:
Credit: Schmid et al., 2005
PCVs model impacts on global GNSS solutions
~ 25 different antenna types
~ 145 individual antennas
> 400 individual calibrations
Individual calibrated antenna PCV can be accessed at:
ftp://ftp.ga.gov.au/geodesy-outgoing/gnss/products/antenna/
Antennas calibrated at GA as of November 2016
Case study: comparison position impact of using
IGS-type mean and individual PCV models
Data source: Northern Surat Basin QLD Campaign 2015
Stations: 65
Antenna types used: 4 (TRM57971.00, TRM55971.00,TPSG3_A1, and
LEIAR10)
Observed days: 20 days, 15-28 Sept and 13-18 Oct 2016
Antennas for Surat QLD 2015 GPS campaign
TRM57971.00 NONE (L1)
Antennas for Surat QLD 2015 GPS campaign
TRM57971.00 NONE (L2)
Significant difference
among different
antennae in terms of
serial numbers
Antennas for Surat QLD 2015 GPS campaign
TPSG3_A1 NONE (L1)
Antennas for Surat QLD 2015 GPS campaign
TPSG3_A1 NONE (L2)
Antennas for Surat QLD 2015 GPS campaign
LEIAR10 NONE (L1)
Antennas for Surat QLD 2015 GPS campaign
LEIAR10 NONE (L2)
Position differences between using IGS-type mean
and individual PCV models
TRM57971.00 NONE antenna better agreement with IGS type
mean
Maximum position difference is 20.9 mm in vertical
component of site SB56, which is TPSG3_A1 NONE antenna
Horizontal component position differences are within 3 mm
Large position differences for vertical component but
correlates with antenna type
Findings from the comparison between IGS type
mean and individual PCV
• Should we give up IGS type mean PCV and use individual
PCV models?
• Suggestions: use IGS type mean PCV for IGS stations which
will keep consistency with IGS products and use individual
PCV as many as possible for other non-IGS stations
Discussions
Phone: +61 2 6249 9884
Web: www.ga.gov.au
Email: [email protected]
Address: Cnr Jerrabomberra Avenue and Hindmarsh Drive, Symonston ACT 2609
Postal Address: GPO Box 378, Canberra ACT 2601
Questions?
Special Case: Damaged Antenna –
ASH701945E_M__NONE (L2)
Special case: damaged antenna –
ASH701945E_M__NONE (L1)
Repeatability of PCV for reference antenna
TRM59800.00 NONE (L2)
L2 dPCV < 2 mm
Repeatability of PCVs for reference antenna
TRM59800.00 NONE (L1)
L1 dPCV < 1.5 mm
Individual antennas – TRM59800.00__NONE (L1)
Significant difference
among different
antennas in terms of
serial numbers
Individual antennas – TRM59800.00__NONE (L2)
Individual antennas – TRM29659.00__NONE (L1)
Individual antennas – TRM29659.00__NONE (L2)
First ever robot calibrated antenna:
ASH701945.B__NONE (L1)
First ever robot calibrated antenna:
ASH701945.B__NONE (L2)
Individual antennas – TRM57971.00__NONE (L1)
Individual antennas – TRM57971.00__NONE (L2)
Not all GNSS satellite antenna are luckily calibrated
Estimation of satellite antenna corrections from IGS re-
processing campaign using global GNSS data
Satellite antenna calibration method
GA robotic GNSS antenna calibration operational since 2014
Several antennas previously did not have robot calibrations
Summary and conclusions
Why we need to do antenna calibrations
Antenna calibration history
GA’s antenna calibration facility (ACF)
Impact on estimated station position when using individual
PCVs
Summary and discussions
Overview
Credit: www.ngs.noaa.gov