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NEW (Cont’d) NEW (SINCE 2010)
USNO Analysis Center Progress 2010-2
C. Hackman, V.J. Slabinski, J.C. Tracey and S.M. Byram
United States Naval Observatory, Washington DC USA
For more information: Christine Hackman, US Naval Observatory, 3450 Massachusetts Ave NW, Washington, DC 20392, USA. Tel: (202) 762-1428. e: christine.hackman@usno.navy.mil. Products online: http:/www.usno.navy.mil/USNO/earth-orientation/gps-products
r u
u u
r
AC HISTORY AND PRODUCTS
• AC since 1997
• Contribute rapid and ultra-rapid solutions
• NEW: Produce IGS Final Troposphere Estimates
• NEW: Testing GLONASS processing
• Products generated using Bernese GPS Software
• Statistics below: 6 Jan 2009 – 30 Jun 2012; 5-s filtered
10
20
30
40
50
60
2009 2010 2011 2012
MM
YEAR
MEDIAN WRMS, USNO ORBIT WRT IGS RAPID
rapid
ultra past
ultra pred
10
100
1000
10000
2009 2010 2011 2012
PS
YEAR
MEDIAN RMS, USNO CLOCKS WRT IGS RAPID
stdev, rapid
RMS, rapid
RMS, ultra pred
0
50
100
150
200
250
300
350
400
2009 2010 2011 2012
MIC
RO
AR
C S
EC
USNO MEDIAN ERP RMS WRT IGS FINAL
x rap
y rap
x ult past
y ult past
x ult pred
y ult pred
96.5
97
97.5
98
98.5
99
99.5
100
2009 2010 2011 2012
%
USNO ON-TIME SUBMISSION RATE
ultras
rapids
On-time rate. Rapids: 100% on-time rate
maintained. Ultras: ~99% on-time. 2012:
missed 11 submissions 3-6 Jun due to
unscheduled network outage. Offsite
backup operations would have mitigated.
Note: Dr. V. Slabinski has made numerous improvements to automation.
Pre-transfer comparison. USNO test troposphere solutions WRT existing IGS Final estimates, 28 Feb – 14 Mar 2011. (Byram et al., 2011).
CHAIR IGS TROPOSPHERE WORKING GROUP
• Dr. C. Hackman, chair
• WG goal: improve accuracy, usability of IGS tropo estimates
• 40 members recruited Fall 2011
• Charter revised Fall 2011
• Survey distributed Winter 2012
IGS FINAL TROPOSPHERE ESTIMATES (FTEs)
• USNO now produces IGS FTEs
• Operations transferred from JPL July 2011
• IGS FTEs dated 17 April 2011 and after generated by USNO
• Dr. Sharyl Byram, project manager
• mm-level RMS agreement in total delay/N gradient/E gradient achieved for 18 station/25 d test prior to operations transfer
• 300+ stations processed daily
• More info: Poster 06-01, Byram & Hackman
SUB-DAILY UTGPS (2011)
• Mr. J. Tracey, project manager
• UTGPS: GPS-based extrapolator of VLBI UT1-UTC measurements used to predict UT1-UTC
• Was generated daily using IGR
• Now generated 4*/d using IGU
• Enables USNO Earth Orientation Dept to predict UT1-UTC 4*/day
NEW STUDY: PPP WITH USU PREDICTS
• Predictions suitable for RT applications
• Initial study: concatenate predicted orbits, clocks, EOPs (no filtering)
• Do PPP with these, IGS Finals
• Sites: AMC2, NIST, USN3 (all USA), PTBB (DE), IENG (IT)
• 26 Mar - 1 Apr 2012 (MJD 56012-8)
• Obtain 7-9 cm position repeatability
• ~ 1 ns RMS time transfer wrt IGSF
• More info: Hackman et al. (2012b)
83
84
85
86
87
88
89
90
91
56012 56013 56014 56015 56016 56017 56018 56019
NS
MJD
NIST-AMC2 (147 km)
USU
IGS-P
IGS
USU-IGS RMS = 864, STDEV = 719, MEAN = 478 ps
503
504
505
506
507
508
509
510
511
512
56012 56013 56014 56015 56016 56017 56018 56019
NS
MJD
PTBB-IENG (835 km)
USU
IGS-P
IGS
USU-IGS RMS = 1016, STDEV = 1007, MEAN = -131 ps
FUTURE PLANS
• Improve PM, no. stations, rapid clocks.
• Develop off-site backup operation.
• Incorporate GLONASS into IGS submissions.
• Troposphere: perform Repro 2; incorporate WG recommendations.
-6
-5
-4
-3
-2
-1
0
1
56012 56013 56014 56015 56016 56017 56018 56019
NS
MJD
USN3-AMC2 (2361 km)
USU
IGS-P
IGS
USU-IGS RMS = 902, STDEV = 900, MEAN = 55 ps
-517
-515
-513
-511
-509
-507
56012 56013 56014 56015 56016 56017 56018 56019
NS
MJD
USN3-PTBB (6275 km)
USU
IGS-P
IGS
USU-IGS RMS = 1474, STDEV = 1417, MEAN = 407 ps
1
10
100
1000
0 1 2 3 4 5 6
RM
S, M
M
SITE (1=AMC2, 2=NIST, 3=USNO, 4= PTBB, 5=IENG)
COORDINATE REPEATABILITY
N-PPU
E-PPU
H-PPU
N-PPI
E-PPI
H-PPI
MEDIAN: 72, 80, 93 mm (N, E, H PPU); 3, 6, 6 mm (N, E, H PPI)
0.0001
0.001
0.01
0.1
1
0 2000 4000 6000 8000
RM
S, M
M
DISTANCE (KM)
SITE A TO B: REPEATABILITY vs LENGTH
DN-PPU
DN-PPI
DE-PPU
DE-PPI
DH-PPU
DH-PPI
DL-PPU
DL-PPI
MEDIAN: 74, 150, 160, 165 mm (dN, dE, dH, dL PPU); 4, 8, 6, 7 mm (dN, dE, dH, dL PPI)
GLONASS PROCESSING
• Test adding GLONASS data to network processing
• Dr. S. Byram, project manager
• Rapid products generated/tested since Winter 2012
• One result: adding GLONASS data reduces z-axis rotation wrt IGR
• Findings presented at ION PLANS 2012 (Byram & Hackman, 2012c)
• Ultra-rapid products to be completed Summer 2012
• See Poster 10-02, Byram & Hackman, for more details
Timing results. USU = PPP results obtained using USNO predicted values; IGS-P = PPP results using IGSF; IGS = IGS Final Clock values
Coordinate precision. PPU, PPI = PPP results obtained using USNO predicts or IGS Finals. PPU coordinate precision is 7-9 cm; no cancellation of errors with subtraction. (Not shown: PPI, PPU agree well within RMS).
Polar motion & LOD. PM (left): Rapids: Median RMS 134-191 marc sec wrt IGS
Final; note 2012 improvement. Ultras: Median RMS 134-217 mm wrt IGS Final, post-
processed portion; 304-376 mm for 24-h predict. LOD (right): Rapids: Annual RMS
residual 16-19 ms wrt IGR.
14.5
15
15.5
16
16.5
17
17.5
18
18.5
19
19.5
2009 2010 2011 2012
MIC
RO
SEC
USNO RAPID LOD RESIDUAL WRT IGS RAPID
2010-2 IGS-Related Bibliography S. Byram & C. Hackman, Computation of the IGS Final Troposphere Product by the USNO, Poster 06-01, 2012 IGS Workshop, Olstzyn, Poland, 2012a.
S. Byram & C. Hackman, GNSS-Based Processing at the USNO: Incorporation of GLONASS Observations, Poster 10-02, 2012 IGS Workshop, Olstzyn, Poland, 2012b.
S. Byram & C. Hackman, High-Precision GNSS Orbit, Clock and EOP Estimation at the United States Naval Observatory, Proc. 2012 IEEE/ION Position Location and Navigation Symposium, 5 pp, in press, 2012c.
S. Byram, C. Hackman & J. Tracey, Computation of
a High-Precision GPS-Based Troposphere Product by the USNO, Proc. ION GNSS 2011, 572-578, 2011.
C. Hackman, V.J. Slabinski, J.C. Tracey & S.M. Byram, USNO Analysis Center Progress 2010-2, Poster 10-07, 2012 IGS Workshop, Olstzyn, Poland, 2012a.
C. Hackman, S.M. Byram, V.J. Slabinski & J.C. Tracey, Near-Real-Time and Other High-Precision GNSS-Based Orbit/Clock/Earth-Orientation/Troposphere Parameters Available from USNO, Proc. 2012 ION Joint Navigation Conference (JNC), 15 pp, in press, 2012b.
C. Hackman, S. Byram, V. Slabinski & J. Tracey, United States Naval Observatory Analysis Center Report 2011, IGS Technical Report 2011, 6 pp, in
press, 2012c.
C. Hackman & S. Byram, IGS Troposphere Working Group 2011, IGS Technical Report 2011, 6 pp, in press, 2012d.
C. Hackman & D. Matsakis, Precision and Accuracy of USNO GPS Carrier Phase Time Transfer: 2012 Update, Proc. IEEE International Frequency Control Symposium (IFCS), 6 pp, in press, 2012e. C. Hackman, High-Precision Low-Latency GPS-Carrier-Phase-Based Satellite Orbits, Clocks and Geophysical Parameters Available from the USNO, Proc. 2011 ION JNC, 1163-1177, 2011a.
C. Hackman & D. Matsakis, Precision and Accuracy of USNO GPS Carrier Phase Time Transfer: Further Studies, Proc. 2011 Joint Conference, IEEE IFCS &
European Frequency and Time Forum, 1046-1051, 2011.
C. Hackman, Impact of Network De-Densification on GPS-Estimated Polar Motion: a Simulation Study, European Geosciences Union General Assembly. 2011b.
C. Hackman & D. Matsakis, Accuracy and Precision of USNO GPS Carrier Phase Time Transfer, Proc. 42nd Ann. Precise Time and Time Interval (PTTI) Systems and Applications Meeting, 16 pp, 2010. C. Hackman, V. Slabinski, J. Tracey, S. Byram & B. Luzum, The USNO Analysis Center: Progress, Problems and Future Expansion, International GNSS Service (IGS) Workshop, Newcastle, England, 2010.
Improved z-axis orientation. Z-axis rotation wrt IGR orbit. Control = GPS only; RMS = 104 mas. GNSS = GPS+ GLONASS; RMS = 76 mas. 23 Feb – 7 Jul 2012.
Orbits & clocks. Orbits (left): Rapids: Median WRMS 14-17 mm wrt IGR. Ultras:
Median WRMS 19-21 mm wrt IGR, post-processed portion; 44-49 mm for 6-h predict.
Clocks (right): Rapids: Median standard deviation/RMS of 52-59/124-145 ps wrt IGR.
Ultras: 6-h predict has 2286-2862 ps median standard deviation wrt IGR. Internal
studies indicate difficulty predicting Block IIA clocks (Hackman et al. 2012b).
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