GOVUS-a new on-line tool for the evaluation of SLR observations to GPS, GLONASS, Galileo, BeiDou and QZSS

Conference Paper (PDF Available) · October 2017with 81 Reads
Conference: Riga, Latvia, Conference: 2017 ILRS Technical Workshop “Improving ILRS Performance to Meet Future GGOS Requirements”, 02-05 October, 2017, At Riga, Latvia
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Abstract
In the last decade, we have been witnessing a radical development of the new GNSS constellations. Besides the well-known GPS and GLONASS systems, newly developed systems such as Galileo, BeiDou and QZSS, become increasingly important. Thanks to adapting of the new generations of GNSS satellites to the SLR requirements, SLR became a valuable source of data. On the other hand, the constantly increasing number of the SLR targets imposes a great challenge for the ILRS tracking stations. In March 2017 a new ILRS Associated Analysis Center (ACC) was established with the main focus on the identification of systematic errors in SLR observations to new GNSS constellations, as well as for the assessment of the quality of multi-GNSS orbit products. The main service offered by the new ILRS ACC is the multi-GNSS Orbit Validation Visualizer Using SLR (GOVUS). The system performs a near real-time SLR validation of multi-GNSS microwave-based precise orbit products delivered by the Center for Orbit Determination in Europe (CODE) in the framework of the IGS MGEX project and covers five different GNSS systems: GPS, GLONASS, Galileo, QZSS, BeiDou MEO and IGSO. GOVUS allows for analyzing and visualizing the validation results using the dedicated on-line applications. The computational algorithms make use of the modified Bernese GNSS Software and provide fully automatic validation of new orbit products as a daily routine. GOVUS system is a useful tool for the both, the ILRS and multi-GNSS community. The dataset of nearly half a million archival SLR residuals, which covers the time span since 2012, is being updated every day. The current and the past performance of the 40 ILRS stations, in terms of quantity and quality of data, can be easily investigated in the aspect of the GNSS tracking and finding systematic biases. Moreover, the validation results of 61 GNSS satellites from 5 systems, can be analyzed on the web browser without installation of any additional software. We present a comprehensive overview of the functionality and the structure of the developed system, as well as examples of analyses performed using the service modules. The analysis of the laser stations’ performance reveals a heterogeneity of the SLR dataset in the context of the accuracy, the station systematics and compliance with the ILRS priorities list. The dependencies between the SLR residuals and particular stations’ equipment will also be examined, e.g., the single and multi-photon mode of signal detection, differences between event and interval timers, 10Hz and kHz stations’ performance.
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Radosław Zajdel, Krzysztof Sośnica, Grzegorz Bury
Institute of Geodesy and Geoinformatics, WUELS, Poland
GOVUS a new on-line tool for the
evaluation of SLR observations to GPS,
GLONASS, Galileo, BeiDou and QZSS
Riga Latvia
ILRS Technical Workshop
October 2-5 2017
How do we evaluate our current performance?
New ILRS AAC at IGG
New ILRS Associate Analysis Center at the Institute of
Geodesy and Geoinformatics, WUELS, Wroclaw,
Poland
https://ilrs.cddis.eosdis.nasa.gov/science
/ILRS_LARGE_sg/index.html
http://www.govus.pl
Main goal: Processing of SLR observations to new GNSS systems:
GLONASS, Galileo, BeiDou, QZSS, GPS Block III (in future) and supporting
the MGEX/LARGE activities
* IGS Multi-GNSS Pilot Project
** ILRS Study Group: Laser Ranging to GNSS s/c Experiment
Current activities
1. Validation of microwave-based GNSS orbits using SLR observations
(Near-real time every day validation) fast feedback for stations
2. Web-application development (GOVUS) for the analysis
of SLR residuals to GNSS
A. maintain the database storing data related with SLR@GNSS
Overview
MGEX
GPS
GLONASS
Galileo
BeiDou
QZSS
NAVIC
Current activities (1) Orbit validation
50 000 km
40 000
30 000
20 000
10 000
Earth
BeiDou MEO
GLONASS
Galileo
GPS
BeiDou
IGSO/GEO
QZSS
Galileo Ext.
Currently we are focused on the CODE* orbit solution, which is
delivered in the frame of MGEX (Prange et al. 2017)
GLONASS, Galileo, BeiDou-2 (excluding GEO), QZSS
~60 satellites
Computational process of SLR validation is made using modified
version of Bernese GNSS software* (version 5.2)
**
* Center for Orbit Determination in Europe
Current activities (1a) Daily Reports and Database System
What we can find ?
Summary of validation result covering last 20 days
from submmision date in reference to the availability of
new ephemeris end Earth Rotation Parameters
About the authors and solution (SLRF2014,
Antenna Thrust and Albedo Model)
Where ?
On the webpage
http://www.govus.pl/slr/daily/
Using the url pattern
govus.plreport/17%doy_REPORT.ALL
doy is a „day of the year” of report submision
Example
http://govus.pl/report/17077_REPORT.ALL
download report from 77th day of the year 2017
Current activities (1b) Daily Reports and Database System
We maintain the accesible database system which includes SLR@GNSS information about:
ILRS laser stations (including detector type, repetition rate, energy, timer type, wavelength)
satellites (information about the orbit, plane, slot, time variables such as antenna and LRA offsets, PRN)
SLR residuals (since 2012, time, in Sun-Satellite-Earth frame)
Nr
Code
Place
Count
Plate
SUBN
Long
[°]
Lat [
°]
Laser
Type
WL
[nm]
Timer
1884
RIGL
Riga
Latvia
Eurasian
EUROLAS
56.948 N
24.059 E
ND:YAG
532
event
Identification Date Offset Satellite Orbit SLR/LRA
PRN
SVN
COSPAR
NORAD
From To
Offset
MV
Offset
LRA
Mass
[kg] Type
System
orbit plane
slot
ALT [km]
RP [h]
i [°]
e Size
Coat CC CC dim
Shape
E18
201
2014
-050A
40128
22/08/14
Active
0.1600
-0.0100
1.0500
1.0199
0.0140
0.5585
661.0
FOC
Galileo
MEO
E
-Ext
1
23225
12.94
50.1
0.002
331.0/
248.7
NO
60
28.2/19.1
rectangular
NR
PRN
SVN
Date
Time
Res
[mm]
Az
[°
]
Elev
[°] Az.
Sat
. [
°]
Nadir
[°]
Δu
[°
]
Β [°]
7090
E12
102
12/05/25
00:22
-18.8
248.67
56.88
77.03
6.77
-112.77
61.34
What can we do with the data ? (1) GOVUS
PLOT
ANALYSES
STATION
STATS
MAP
TOOLS
TABLES
CHARTS
SATELLITE
STATS
Analyses using the GOVUS on-line application:
http://www.govus.pl
How can we read the data ? (1) GOVUS
Using GOVUS we can easily generate filtered dataset
select particular stations or satellites, change the timerange, limit to specific feature
(detector/timer type, orbital plane): check the prepared form (multi-slrgnss.rhcloud.com/slr/plot)
The tutorial movie available at: (multi-slrgnss.rhcloud.com/slr/info)
Analyse and download the plots:
dozen of different plots Generate tables with core statistics
general, for stations and satellites
How can we read the data ? (2) GOVUS SQL Explorer
We share the structure of the database and the
tool, which allow to perform the raw sql query:
multi-slrgnss.rhcloud.com/explorer
The tutorial movie available at: (multi-slrgnss.rhcloud.com/slr/info)
ask for account:
radoslaw.zajdel@igig.up.wroc.pl
What can we do with the data ? GNSS tracking performance of laser stations
GOVUS is a great source of information about the stations’ performance
Galileo GLONASS QZSS
RANK
STATION
NO. OBS.
SATELLITES
% OF OBS.
STATION
NO. OBS.
SATELLITES
% OF OBS.
STATION
NO. OBS.
SATELLITES
% OF OBS.
1
7090
7082
13
19
,3
7090
8112
13
11
,8
7
237
556
1
53
,1
2
7839
3627
13
9
,9
7839
8081
26
11
,8
7821
213
1
20
,3
3
7237
3623
13
9
,9
7237
6466
16
9
,4
7090
210
1
20
,1
4
7825
3240
13
8
,8
7840
5489
26
8
,0
7825
34
1
3
,3
5
8834
2812
13
7
,6
1879
3993
16
5
,8
7249
33
1
3
,2
6
7840
2804
13
7
,6
8834
3978
26
5
,8
7
7941
2288
13
6
,2
1868
3903
16
5
,7
8
7821
1500
12
4
,1
7821
3875
23
5
,6
Total
73
,4
63
,9
100
Check the distribution
of observations for
particular systems
What can we do with the data ?
How do we track multi-GNSS
constellation ?
Monitor the number of Normal
Points to particular satellites
collected by specific laser
stations in selected timerange
The status of Expanded SLR
Tracking Campaigns of GNSS
Satellites
How do we meet the requirements of
the ILRS tracking priority list
Campaign II Campaign III
ILRS priority list
What can we do with the data ? Vulnerability to Satellite Signature Effect
We can monitor the systematics related to the stations for example the Satellite Signature Effect
Dataset: uncoated GLONASS-M; year: 2016
Multi-photon detectors are more affected to the Satellite Signature Effect
What can we do with the data ? Analyses of stations’ histograms
Histograms of SLR residuals to investigate the different types of systemtics
Systematic offset
Double peak of the histogram
Disturbed/skewed normal distribution
Dataset: uncoated GLONASS-M; year: 2016
What can we do with the data ?
Discontinuities in tracking
resulted from the stations’
upgrades or any unexpected
problems
FROM TO DURATION
DATE DOY DATE DOY [days]
27.08.2016
240 10.02.2017
41 166
19.07.2016
201 25.08.2016
238 37
24.06.2016
176 18.07.2016
200 24
23.03.2016
83 11.04.2016
102 19
19.11.2015
323 22.03.2016
82 124
03.11.2014
307 23.04.2015
113 171
07.07.2014
188 23.07.2014
204 16
08.06.2013
159 05.07.2013
186 26
12.12.2012
347 16.02.2013
47 65
23.10.2012
297 12.12.2012
347 50
What can we do with the data ? Station tracking as a function of local time
?
Number of observations
Lack of NP
Differences in average SLR residuals
complex dependencies
Dataset: uncoated GLONASS-M; year: 2016
Assessment of multi-GNSS orbit quality (model change)
TYPE COATING
Mean [mm] St. Dev [mm] No. Obs.
NEW OLD NEW OLD NEW OLD
GALILEO
FOC NO -3,2 -35,7 19,6 34,4 1892 2951
FOC (ext.)
NO -1,9 -40,6 13,7 20,7 290 510
IOV NO -6,2 -53,8 14,4 31,2 685 1016
GLONASS
K1 NO -6,6 -14,3 36,7 21,4 500 795
M YES -3,5 -12,9 29,3 29,6 312 442
M NO -14,7 -18,7 23,8 26,7 3292 5422
M+ NO 28,4 15,1 16,0 22,4 304 417
OLD (07/2017) WITHOUT ALBEDO AND
ANTENNA THRUST FOR GLONASS, GALILEO
AND QZSS
NEW (08/2017) WITH ALBEDO AND ANTENNA
THRUST FOR GLONASS, GALILEO AND QZSS
The mean SLR residuals for the
Galileo and GLONASS satellites
decreased to the single
milimeters.
Decrease of the mean SLR
residuals and the standard
deviation indicate a better
consistency between SLR and
GNSS solutions.
OLD NEW
Galileo
Conclusions
The web application is working with the functionality of:
storing and updating database in a daily routine
visualizing data and allowing for plot analyses
creating dataset filtered by a user, ready for download
The service is a great tool for laser stations to monitor their
performance refered to GNSS tracking
The service is also a great source of information about the multi-GNSS
orbit quality (GPS, GLONASS, Galileo, BeiDou, QZSS) From 2012 to
Despite of being fully operational, service is still in development stage,
therefore we encourage for testing and send your feedback
What do you think about the project ?
How can we adjust the functionality to the stations’ needs?
Radosław Zajdel
radoslaw.zajdel@igig.up.wroc.pl
Institute of Geodesy and Geoinformatics
Thank you for your attention
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