UNAVCO REAL-TIME RESOURCES: NETWORK STATUS: http://www.unavco.org/instrumentation/networks/status/pbo/r ealtime UNAVCO DATA POLICY: http://www.unavco.org/community/policies_forms/data- policy/DataStreamingPolicy.pdf NTRIP SOURCETABLE: http://rtgpsout.unavco.org:2101 REQUEST REAL-TIME ACCESS: http://www.unavco.org/data/data-help/custom-data- request/custom-data-request.html UNAVCO is funded by the National Science Foundation (NSF) and National Aeronautics and Space Administrations (NASA). The GAGE facility, managed by UNAVCO, operates a real-time GNSS (RT-GNSS) network of ~450 GNSS stations. The network includes stations that are part of the EarthScope Plate Boundary Observatory (PBO), the Continuously Operating Caribbean GPS/GNSS Observational Network (COCONet), and the Trans-boundary, Land and Atmosphere Long-term Observational and Collaborative Network (TLALOCNet). Following community input from a real-time GNSS data products and formats meeting hosted by UNAVCO in Spring of 2011, UNAVCO now provides real-time PPP positions, and network solutions where practical, for all available stations using Trimble’s PIVOT RTX server software. The UNAVCO real-time system has the potential to enhance our understanding of earthquakes, seismic wave propagation, volcanic eruptions, magmatic intrusions, movement of ice, landslides, and the dynamics of the atmosphere. Beyond the ever increasing applications in science and engineering, RT-GNSS has the potential to provide early warning of hazards to emergency managers, utilities, first responders and others. Recent upgrades to the network include eight Trimble NetR9 GNSS receivers with GLONASS and receiver-based RTX capabilities and ten new collocated MEMS based accelerometers. These new capabilities will allow integration of GNSS and strong motion data to produce broad-spectrum waveforms improving Earthquake Early Warning systems. The UNAVCO Real-Time Network A map of North America showing UNAVCO’s current real-time GNSS network of ~450 stations. The network includes stations that are part of the PBO, COCONet, and TLALOCNet projects. −170˚ −160˚ −150˚ −140˚ −130˚ −120˚ −110˚ −100˚ −90˚ −80˚ −70˚ −60˚ 10˚ 20˚ 30˚ 40˚ 50˚ 60˚ 70˚ There are approximately 129 Real-time GNSS sites with collocated meteorological instruments. The data from these instruments are made available in near-real-time via BINEX streams, and as RINEX files downloadable from our archive. −170˚ −160˚ −150˚ −140˚ −130˚ −120˚ −110˚ −100˚ −90˚ −80˚ −70˚ −60˚ 30˚ 40˚ 50˚ 60˚ 70˚ −119˚00' −118˚30' −118˚00' −117˚30' −117˚00' −116˚30' −116˚00' −115˚30' −115˚00' −114˚30' −114˚00' 32˚30' 33˚00' 33˚30' 34˚00' 34˚30' GLRS P472 P482 P483 P484 P486 P494 P505 P506 SLM S USGC P797 A map of Southern California showing ten sites with recently installed Micro-Electro-Mechanical Systems (MEMS) based accelerometers. Plot of the number of users requesting access to UNAVCO's real time data streams. Non-profit consortia include entities such as NOAA or UCAR. Controlled outdoor kinematic and static experiments provide a useful method for evaluating and comparing real-time systems. At UNAVCO, we have developed a portable antenna actuator to characterize kinematic performance of receiver- and server-based real-time positioning algorithms and identify system limitations. We have performed initial tests using controlled 1-d antenna motions and present recent test results in this poster. GNSS instruments are being used to record large displacements and accelerations from earthquakes that exceed M7. A few researchers have conducted tests to independently characterize GNSS instrument response over seismic frequencies [e.g. Ebinuma and Kato, 2012; Elosegui et al., 2006; Wang et al., 2012; Langbein et al., 2012]. Previous work has shown that receiver response is not frequency independent for signals greater than 1 Hz, and receiver response varies with receiver make and model. In addition, user selectable tracking parameters may affect a receiver’s response. In this paper, we show the response of Trimble’s receiver-based RTX real-time positioning service to frequencies from 0.2-6.0 Hz. UNAVCO will continue evaluations of new commercial and open-source real-time positioning services as they become available. In addition to kinematic testing, long-term static testing of Trimble’s RTX service is ongoing at UNAVCO and will be used to characterize the stability of the position time-series produced by RTX. Outdoor Kinematic Testing Above: UNAVCO’s low-cost antenna actuator. The antenna carriage rides on plastic linear bearings. We employ a 500 mm double-action pneumatic cylinder with position feedback to drive the system. A servo pneumatic proportional control valve provides position control using a 0-10 V command signal. The carriage position is logged at 200 Hz using a Kinemetrics Basalt data recorder. Compressed air is provided by a portable consumer-grade air compressor. Left: The magnitude of the difference between the RTX measured position and true stage po- sition peaks near 3 Hz. Right: The displacement spectrum of the stage (blue) and RTX (red). 10 −1 10 0 10 1 −60 −40 −20 0 20 40 60 log(mm 2 /Hz) Freq, Hz Stage RTX 19:41:25 19:41:30 19:41:35 19:41:40 19:41:45 19:41:50 −100 −50 0 50 100 Stage Position [200sps] [mm] 19:41:25 19:41:30 19:41:35 19:41:40 19:41:45 19:41:50 −100 −50 0 50 100 RTX Position [50sps] [mm] 19:41:25 19:41:30 19:41:35 19:41:40 19:41:45 19:41:50 −100 −50 0 50 100 Difference RTX and Stage Position [mm] 3.0 Hz Sinusoidal shaking (RTX) 2.0 Hz Sinusoidal shaking (RTX) 19:37:00 19:37:15 −200 −100 0 100 200 Stage Position [200sps] [mm] 19:37:00 19:37:15 −200 −100 0 100 200 RTX Position [50sps] [mm] 19:36:50 19:36:55 19:37:00 19:37:05 19:37:10 19:37:15 19:37:20 −200 −100 0 100 200 Difference RTX and Stage Position [mm] Left: Increasing difference between the RTX measured position and true stage position at 2 Hz. Right: The displacement spectrum of the stage (blue) and RTX (red). 10 −1 10 0 10 1 −60 −40 −20 0 20 40 60 log(mm 2 /Hz) Freq, Hz Stage RTX 1.0 Hz Sinusoidal shaking (RTX) 19:35:00 19:35:10 19:35:20 −200 −100 0 100 200 Stage Position [200sps] [mm] 19:35:00 19:35:10 19:35:20 −200 −100 0 100 200 RTX Position [50sps] [mm] 19:35:00 19:35:10 19:35:20 −200 −100 0 100 200 Difference RTX and Stage Position [mm] Left: Small differences between RTX measured position and true stage position at 1 Hz. Right: The displacement spectrum of the stage (blue) and RTX (red). 10 −1 10 0 10 1 −60 −40 −20 0 20 40 60 log(mm 2 /Hz) Freq, Hz Stage RTX −60 −50 −40 −30 −20 −10 0 10 Phase, deg. 0.1 1.0 10 Frequency, Hz We also observe a frequency-dependent re- sponse in the phase of the estimated displace- ment of the antenna while undergoing sinusoi- dal shaking. 0.1 1.0 10 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 Frequency, Hz Gain Similar to the post-processed results of Ebinuma and Kato (2012) and Langbien et al. (2012) we observe that RTX has a frequency-dependent response when the antenna undergoes sinusoi- dal motion. RTX Testing Results: Frequency [Hz] Stage Amplitude [mm] RTX Amplitude [mm] Phase Difference [deg] 0.2 156.7 155.14 0.77 0.2 157.46 156.6 0.897 0.5 157.51 158.81 1.211 0.5 157.82 159.6 1.266 1 159.41 162.24 2.85 2 104.37 119.6 11.395 3 50.183 82.809 5.85 4 31.46 51.933 -7.55 5 41.631 64.086 -21.423 6 39.22 58.455 -29.8 Test Configuration: Receiver Type: NetR9 Antenna Type: Trimble Zephyr Position Solution: RTX receiver based PPP service Receiver Motion: Kinematic (not filtered) RTK Engine Motion: Kinematic Constellations: GPS + GLONASS Sinusoidal Test Duration: 30 seconds An example of carriage displacement error while reproducing a 1 Hz sinusoid. We will be adding an accumulation tank to the system to increase positioning accuracy. 19:35:00 19:35:05 19:35:10 −200 −100 0 100 200 [mm] 19:35:00 19:35:05 19:35:10 −20 −10 0 10 20 [mm] Error Stage Sine Test Apparatus UNAVCO Real-Time GNSS Positioning: High-Precision Static and Kinematic Testing of the Next Generation GNSS Network AGU FALL MEETING 2014 Henry Berglund ([email protected]), Kathleen Hodgkinson, Frederick Blume, Dave Mencin, David Phillips, Chris Walls, Doerte Mann, Christine Puskas, Otina Fox, Chuck Meertens and Glen Mattioli UNAVCO, Boulder, CO 80301-5553 Left: A schematic showing UNAVCO’s real-time data flow. BINEX streams from telemetered stations are col- lected by primary and sec- ondary servers in the PIVOT system. At this point the BINEX is sent to the archive for permanent storage and to the primary and second- ary castors for streaming to the public. The NTRIP castors distribute RTCM, BINEX, and position streams to regis- tered users. RINEX is also generated and available for download from the archive via FTP. Right: P484 in Southern California. A MEMS accelerometer is clamped to the vertical leg of the monument. The instrument is connected to the Geodetic Module (below) which is mounted inside the GPS enclosure. The Geodetic Module combines GPS and seismic data on location. References: Ebinuma, T. and T. Kato, Characteristics of Very-High-Rate GPS for Seismology, Earth Planets and Space, 64, 2012. Elósegui, P., J. L. Davis, D. Oberlander, R. Baena, and G. Ekström. "Accuracy of high‐rate GPS for seismology." Geophysi- cal research letters 33, no. 11 (2006). Langbein, J. O., J. R. Evans, F. Blume, and I. A. Johanson. "Tests of GNSS receivers for dynamic, high sample rate response using controlled sources of displacement, velocity, and acceleration." In AGU Fall Meeting Abstracts, vol. 1, p. 1122. 2012. Wang, G., F. Blume, C. Meertens, P. Ibanez, and M. Schulze. "Performance of high-rate kinematic GPS during strong shaking: observations from shake table tests and the 2010 Chile earthquake." Journal of Geodetic Science 2, no. 1 (2012): 15-30. Summary: Our preliminary testing indicates that the re- sponse of RTX is not frequency independent and care must be taken with interpreting ob- servations that contain frequencies greater than 1Hz. Our future testing will compare RTX performance with and without GLONASS. As new commercial and open-source real-time positioning services become available, they will be included in our testing. In addtion we will evaluate the response of receivers to shak- ing, as all testing to date has been conducted with only the antenna undergoing motion. Latency and completeness of the MEMS sites in Anza. The figure shows the latency at 1 hour interval for the 1-sps RTGPS data. The table below the plot summarizes the completeness of the data at 1 hour intervals and the latencies using both the median and the mean. Summary of the latencies across the network. 1-hour latencies were extracted for all PBO MEMs sites between 11/1/2014 and 11/24/2014 from the RTGPS database. The sites were sorted by telemetry type. Offline sites were excluded. There are two side peaks on the CDMA trace, one at ~75 ms and another at 500 ms. This may indicate a regional network issue. Power spectral density plots for the MEMs sites. This analysis was done with data col- lected from Nov. 1-2. The vertical component is much noisier, as expected. All the site have similar noise characteristics. However, P494 and P505 are quieter in the 0.1 to 0.01 Hz band. The calculations were made using a 1 hour, 50% overlapping window, with a Welch estimator. 0 100 200 300 A J O J A J O J A J O J A J O J A J O 2010 2011 2012 2013 2014 Number Of Registered Users Government and Non-Profit Consortia Commercial Total Academia Number of Users Registered for UNAVCO RTGPS Data Streams UNAVCO Real-Time GNSS Network Real-Time Meteorological Data Real-Time Sites With MEMS Who’s Using The Data? Examples Of Network Performance Real time-Enabled GPS + Met Network PIVOT SYSTEM HIGH-RATE DATA STREAM HIGH-RATE DATA FILE Data Input Data Output BINEX Primary Caster Mars Secondary Caster Theia Primary Stream Control + Data Processing Secondary Stream Control + Data Processing BINEX Load Balancer Permanent GPS Archive RINEX Survey Users Research Users RTCM BINEX, Position 0 5000 10000 15000 0 200 400 600 800 1000 CDMA 243 173 DIRECT CONNECTION 29 107 DSL WISP 4 66 RADIO 122 239 VSAT 9 866 Communications Sites Median (ms) Number Of Observations Latency versus Communications Latency (milliseconds) 0 10 20 30 0 200 400 600 800 1000 Latency (milliseconds) Percentage B) Latency Normalized by number of Observations A) Number of Observations versus Latency 1 10 100 1000 0.001 0.01 0. 1 East P484 P494 P505 P506 P797 Frequency (Hz) 1 10 100 1000 0.001 0.01 0. 1 North P484 P494 P505 P506 P797 Frequency (Hz) 1 10 100 1000 10000 0.001 0.01 0. 1 Up P484 P494 P505 P506 P797 mm 2 /Hz Frequency (Hz) mm 2 /Hz mm 2 /Hz P484 100 99.9 118 176.0 P494 100 99.2 5 20.4 P505 100 95.3 46 264.7 P506 100 98.4 1 49.4 P797 100 99.8 70 81.4 50 100 150 200 20 27 03 10 17 Completeness and Latency of RTGPS + MEMs Sites Completeness(%) Latency (ms) GPS Median Mean Median Mean Completeness % 0 October 2014 November 2014
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UNAVCO REAL-TIME RESOURCES:NETWORK STATUS:
http://www.unavco.org/instrumentation/networks/status/pbo/realtime
UNAVCO DATA POLICY:
http://www.unavco.org/community/policies_forms/data-policy/DataStreamingPolicy.pdf
NTRIP SOURCETABLE:
http://rtgpsout.unavco.org:2101
REQUEST REAL-TIME ACCESS:http://www.unavco.org/data/data-help/custom-data-request/custom-data-request.html
UNAVCO is funded by the National Science Foundation (NSF) and National Aeronautics and Space Administrations (NASA).
The GAGE facility, managed by UNAVCO, operates a real-time GNSS (RT-GNSS) network of ~450 GNSS stations. The network includes stations that are part of the EarthScope Plate Boundary Observatory (PBO), the Continuously Operating Caribbean GPS/GNSS Observational Network (COCONet), and the Trans-boundary, Land and Atmosphere Long-term Observational and Collaborative Network (TLALOCNet). Following community input from a real-time GNSS data products and formats meeting hosted by UNAVCO in Spring of 2011, UNAVCO now provides real-time PPP positions, and network solutions where practical, for all available stations using Trimble’s PIVOT RTX server software.
The UNAVCO real-time system has the potential to enhance our understanding of earthquakes, seismic wave propagation, volcanic eruptions, magmatic intrusions, movement of ice, landslides, and the dynamics of the atmosphere. Beyond the ever increasing applications in science and engineering, RT-GNSS has the potential to provide early warning of hazards to emergency managers, utilities, �rst responders and others. Recent upgrades to the network include eight Trimble NetR9 GNSS receivers with GLONASS and receiver-based RTX capabilities and ten new collocated MEMS based accelerometers. These new capabilities will allow integration of GNSS and strong motion data to produce broad-spectrum waveforms improving Earthquake Early Warning systems.
The UNAVCO Real-Time Network
A map of North America showing UNAVCO’s current real-time GNSS network of ~450 stations. The network includes stations that are part of the PBO, COCONet, and TLALOCNet projects.
−170˚
−160˚
−150˚−140˚
−130˚ −120˚ −110˚ −100˚−90˚
−80˚
−70˚
−60˚
10˚
20˚
30˚
40˚
50˚
60˚
70˚
There are approximately 129 Real-time GNSS sites with collocated meteorological instruments. The data from these instruments are made available in near-real-time via BINEX streams, and as RINEX �les downloadable from our archive.
−170˚
−160˚
−150˚−140˚
−130˚ −120˚ −110˚ −100˚−90˚
−80˚
−70˚
−60˚
30˚
40˚
50˚
60˚
70˚
−119˚00' −118˚30' −118˚00' −117˚30' −117˚00' −116˚30' −116˚00' −115˚30' −115˚00' −114˚30' −114˚00'
32˚30'
33˚00'
33˚30'
34˚00'
34˚30'
GLRS
P472
P482
P483
P484
P486
P494
P505
P506
SLMS
USGC
P797
A map of Southern California showing ten sites with recently installed Micro-Electro-Mechanical Systems (MEMS) based accelerometers.
Plot of the number of users requesting access to UNAVCO's real time data streams. Non-pro�t consortia include entities such as NOAA or UCAR.
Controlled outdoor kinematic and static experiments provide a useful method for evaluating and comparing real-time systems. At UNAVCO, we have developed a portable antenna actuator to characterize kinematic performance of receiver- and server-based real-time positioning algorithms and identify system limitations. We have performed initial tests using controlled 1-d antenna motions and present recent test results in this poster.
GNSS instruments are being used to record large displacements and accelerations from earthquakes that exceed M7. A few researchers have conducted tests to independently characterize GNSS instrument response over seismic frequencies [e.g. Ebinuma and Kato, 2012; Elosegui et al., 2006; Wang et al., 2012; Langbein et al., 2012]. Previous work has shown that receiver response is not frequency independent for signals greater than 1 Hz, and receiver response varies with receiver make and model. In addition, user selectable tracking parameters may a�ect a receiver’s response. In this paper, we show the response of Trimble’s receiver-based RTX real-time positioning service to frequencies from 0.2-6.0 Hz. UNAVCO will continue evaluations of new commercial and open-source real-time positioning services as they become available.
In addition to kinematic testing, long-term static testing of Trimble’s RTX service is ongoing at UNAVCO and will be used to characterize the stability of the position time-series produced by RTX.
Outdoor Kinematic Testing
Above: UNAVCO’s low-cost antenna actuator. The antenna carriage rides on plastic linear bearings. We employ a 500 mm double-action pneumatic cylinder with position feedback to drive the system. A servo pneumatic proportional control valve provides position control using a 0-10 V command signal. The carriage position is logged at 200 Hz using a Kinemetrics Basalt data recorder. Compressed air is provided by a portable consumer-grade air compressor.
Left: The magnitude of the di�erence between the RTX measured position and true stage po-sition peaks near 3 Hz. Right: The displacement spectrum of the stage (blue) and RTX (red).
10−1 100 101
−60
−40
−20
0
20
40
60
log(
mm
2 /Hz)
Freq, Hz
StageRTX
19:41:25 19:41:30 19:41:35 19:41:40 19:41:45 19:41:50−100
−50
0
50
100
Stage Position [200sps]
[mm
]
19:41:25 19:41:30 19:41:35 19:41:40 19:41:45 19:41:50−100
−50
0
50
100
RTX Position [50sps]
[mm
]
19:41:25 19:41:30 19:41:35 19:41:40 19:41:45 19:41:50−100
−50
0
50
100
Difference RTX and Stage Position
[mm
]
3.0 Hz Sinusoidal shaking (RTX)
2.0 Hz Sinusoidal shaking (RTX)
19:37:00 19:37:15−200
−100
0
100
200Stage Position [200sps]
[mm
]
19:37:00 19:37:15−200
−100
0
100
200RTX Position [50sps]
[mm
]
19:36:50 19:36:55 19:37:00 19:37:05 19:37:10 19:37:15 19:37:20−200
−100
0
100
200Difference RTX and Stage Position
[mm
]
Left: Increasing di�erence between the RTX measured position and true stage position at 2 Hz. Right: The displacement spectrum of the stage (blue) and RTX (red).
10−1 100 101
−60
−40
−20
0
20
40
60
log(
mm
2 /Hz)
Freq, Hz
StageRTX
1.0 Hz Sinusoidal shaking (RTX)
19:35:00 19:35:10 19:35:20−200
−100
0
100
200Stage Position [200sps]
[mm
]
19:35:00 19:35:10 19:35:20−200
−100
0
100
200RTX Position [50sps]
[mm
]
19:35:00 19:35:10 19:35:20−200
−100
0
100
200Difference RTX and Stage Position
[mm
]
Left: Small di�erences between RTX measured position and true stage position at 1 Hz. Right: The displacement spectrum of the stage (blue) and RTX (red).
10−1 100 101
−60
−40
−20
0
20
40
60
log(
mm
2 /Hz)
Freq, Hz
StageRTX
−60
−50
−40
−30
−20
−10
0
10
Phas
e, d
eg.
0.1 1.0 10Frequency, Hz
We also observe a frequency-dependent re-sponse in the phase of the estimated displace-ment of the antenna while undergoing sinusoi-dal shaking.
0.1 1.0 100
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Frequency, Hz
Gai
n
Similar to the post-processed results of Ebinuma and Kato (2012) and Langbien et al. (2012) we observe that RTX has a frequency-dependent response when the antenna undergoes sinusoi-dal motion.
RTX Testing Results:
Frequency [Hz]
Stage Amplitude [mm]
RTX Amplitude [mm]
Phase Difference [deg]
0.2 156.7 155.14 0.770.2 157.46 156.6 0.8970.5 157.51 158.81 1.2110.5 157.82 159.6 1.2661 159.41 162.24 2.852 104.37 119.6 11.3953 50.183 82.809 5.854 31.46 51.933 -7.555 41.631 64.086 -21.4236 39.22 58.455 -29.8
Test Con�guration:
Receiver Type: NetR9
Antenna Type: Trimble Zephyr
Position Solution: RTX receiver based PPP service
Receiver Motion: Kinematic (not �ltered)
RTK Engine Motion: Kinematic
Constellations: GPS + GLONASS
Sinusoidal Test Duration: 30 seconds
An example of carriage displacement error while reproducing a 1 Hz sinusoid. We will be adding an accumulation tank to the system to increase positioning accuracy.
19:35:00 19:35:05 19:35:10−200
−100
0
100
200
[mm
]
19:35:00 19:35:05 19:35:10−20
−10
0
10
20
[mm
]
Error
StageSine
Test Apparatus
UNAVCO Real-Time GNSS Positioning: High-Precision Static and Kinematic Testing of the Next Generation GNSS Network
AGU FALL MEETING 2014
Henry Berglund ([email protected]), Kathleen Hodgkinson, Frederick Blume, Dave Mencin, David Phillips, Chris Walls, Doerte Mann, Christine Puskas, Otina Fox, Chuck Meertens and Glen Mattioli
UNAVCO, Boulder, CO 80301-5553
Left: A schematic showing UNAVCO’s real-time data �ow. BINEX streams from telemetered stations are col-lected by primary and sec-ondary servers in the PIVOT system. At this point the BINEX is sent to the archive for permanent storage and to the primary and second-ary castors for streaming to the public. The NTRIP castors distribute RTCM, BINEX, and position streams to regis-tered users. RINEX is also generated and available for download from the archive via FTP.
Right: P484 in Southern California. A MEMS accelerometer is clamped to the vertical leg of the monument. The instrument is connected to the Geodetic Module (below) which is mounted inside the GPS enclosure. The Geodetic Module combines GPS and seismic data on location.
References:
Ebinuma, T. and T. Kato, Characteristics of Very-High-Rate GPS for Seismology, Earth Planets and Space, 64, 2012.
Elósegui, P., J. L. Davis, D. Oberlander, R. Baena, and G. Ekström. "Accuracy of high‐rate GPS for seismology." Geophysi-cal research letters 33, no. 11 (2006).
Langbein, J. O., J. R. Evans, F. Blume, and I. A. Johanson. "Tests of GNSS receivers for dynamic, high sample rate response using controlled sources of displacement, velocity, and acceleration." In AGU Fall Meeting Abstracts, vol. 1, p. 1122. 2012.
Wang, G., F. Blume, C. Meertens, P. Ibanez, and M. Schulze. "Performance of high-rate kinematic GPS during strong shaking: observations from shake table tests and the 2010 Chile earthquake." Journal of Geodetic Science 2, no. 1 (2012): 15-30.
Summary:Our preliminary testing indicates that the re-sponse of RTX is not frequency independent and care must be taken with interpreting ob-servations that contain frequencies greater than 1Hz. Our future testing will compare RTX performance with and without GLONASS. As new commercial and open-source real-time positioning services become available, they will be included in our testing. In addtion we will evaluate the response of receivers to shak-ing, as all testing to date has been conducted with only the antenna undergoing motion.
Latency and completeness of the MEMS sites in Anza. The �gure shows the latency at 1 hour interval for the 1-sps RTGPS data. The table below the plot summarizes thecompleteness of the data at 1 hour intervals and the latencies using both the median and the mean.
Summary of the latencies across the network. 1-hour latencies were extracted for all PBO MEMs sites between 11/1/2014 and 11/24/2014 from the RTGPS database. The sites were sorted by telemetry type. O�ine sites were excluded. There are two side peaks on the CDMA trace, one at ~75 ms and another at 500 ms. This may indicate a regional network issue.
Power spectral density plots for the MEMs sites. This analysis was done with data col-lected from Nov. 1-2. The vertical component is much noisier, as expected. All the site have similar noise characteristics. However, P494 and P505 are quieter in the 0.1 to 0.01 Hz band. The calculations were made using a 1 hour, 50% overlapping window, with a Welch estimator.
0
100
200
300
A J O J A J O J A J O J A J O J A J O2010 2011 2012 2013 2014
Num
ber O
f Reg
iste
red
Use
rs
Government and Non-Profit ConsortiaCommercial
TotalAcademia
Number of Users Registered for UNAVCO RTGPS Data Streams
UNAVCO Real-Time GNSS Network Real-Time Meteorological Data
Real-Time Sites With MEMSWho’s Using The Data?
Examples Of Network Performance
Real time-EnabledGPS + Met Network
PIVOT SYSTEM
HIGH-RATE DATA STREAM
HIGH-RATE DATA FILE
DataInput
DataOutput
BINEX
Primary CasterMars
Secondary CasterTheia
Primary StreamControl + Data
Processing
Secondary StreamControl + Data
Processing
BINEX
Load BalancerPermanent
GPSArchive
RINEX
SurveyUsers
ResearchUsers
RTCMBINEX,
Position
0
5000
10000
15000
0 200 400 600 800 1000
CDMA 243 173
DIRECT CONNECTION 29 107
DSL WISP 4 66
RADIO 122 239
VSAT 9 866
Communications Sites Median (ms)
Num
ber O
f Obs
erva
tions
Latency versus Communications
Latency (milliseconds)
0
10
20
30
0 200 400 600 800 1000Latency (milliseconds)
Perc
enta
ge
B) Latency Normalized by number of Observations
A) Number of Observations versus Latency
1
10
100
1000
0.001 0.01 0. 1
East
P484P494P505P506P797
Frequency (Hz)
1
10
100
1000
0.001 0.01 0. 1
North
P484P494P505P506P797
Frequency (Hz)
1
10
100
1000
10000
0.001 0.01 0. 1
Up
P484P494P505P506P797
mm
2 /Hz
Frequency (Hz)
mm
2 /Hz
mm
2 /Hz
P484 100 99.9 118 176.0
P494 100 99.2 5 20.4
P505 100 95.3 46 264.7
P506 100 98.4 1 49.4
P797 100 99.8 70 81.4
50
100
150
200
20 27 03 10 17
Completeness and Latency of RTGPS + MEMs Sites
Completeness(%) Latency (ms)GPS Median Mean Median Mean
Com
plet
enes
s %
0
October 2014 November 2014
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