- Email: [email protected]
A review of currently available IGS network summaries
Phys. Chem.Earth (A),Vol.26, No. 6-8, pp. 591-594, 2001 0 2001 ElsevierScience Ltd.
Pergamon
All rightsreserved 1464-1895/01/$ - see front matter
PII: S1464-1895(01)00106-5
A Review of
Currently
Available IGS Network Summaries
A. W. Moore
International GPS Service Central Bureau, Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 238-540, 4800 Oak Grove Dr., Pasadena CA 91109 USA Received 30 July 2000; accepted 18 Januav
2001
Abstract.
All components of the International GPS Serbite (IGS) community have cause to seek metrics, reports, or summaries of the IGS network. Station personnel may wish to monitor the performance of their own stations, users need to select subnetworks of stations appropriate to a particular study, and analysts must understand station configurations to assure high quality results. With its role in day-to-day management and coordination of the IGS, the Central Bureau devises and maintains information appropriate to these needs on its information system, and also refers users to useful summaries maintained at IGS Data Centers and Analysis Centers. This paper reviews the content and possible usage of several network summaries that are located at or useful to the Central Bureau, with the intent of ensuring that the community has ready access to information that enables both assessment and improvement of network performance. Q 2001 ElsevierScience Ltd. All rights reserved 1
Summaries based on site logs
The site logs on file at the IGS Central Bureau (CB) comprise the definitive source for IGS site information. As such, several network summaries are generated from the site logs. The locations for Internet access to the site logs and all other files referred to in this article are given in Table 1. 1.1
The SINEX template igs.snx
A file known as the SINEX (Solution INdependent Exchange format) template was developed by IGS Analysis Centers and the Central Bureau in 1997 with the purpose of standardizing the station metadata across Analysis Centers. The SINEX template is generated daily from the latest site logs at the CB. The SINEX format, which is also used for IGS station and coordinate velocity results, is fully documented at the Correspondence
to: Angelyn W. Moore
location detailed in Table 1; here a brief summary of the features of the SINEX template is presented. The template consists of several sections; in Fig.1, excerpts from the receiver and antenna sections are shown. The block beginning with “SITE/RECEIVER” shows receiver characteristics, starting alphabetically with station ALBH. Each line denotes the range of time by start and ending year, day and time of day that a particular receiver was installed at the site, identifying it by model, serial number, and firmware version. Similarly, the block beginning “SITE/ANTENNA” details the time history of of antenna and radome installations for the ALBH site, including number 95 174, which is active up to the current time as designated by convention with epoch oo:ooo:ooooo. It should be noted that the equipment naming conventions in the SIh%X template follow the accepted IGS codes as laid out in a naming table (see Table 1). Incoming site logs are checked for format compliance and are not accepted if the naming conventions are not followed; however, the SINEX template software continues to perform integrity checks and would post any error found to the SMEX template error file (igs.snx.err; see Table 1). Metadata inconsistencies between the SJ.NEXtemplate and RINEX (Receiver INdependent EXchange format) tracking data headers are also reported in this location, and station operators are automatically notified by email if any errors related to their sites are found. 1.2
loghist.txt
This file is quite similar to the SINEX template in that it is generated from current site logs and indicates a hardware history of IGS sites. The loghist.txt file, however, groups the metadata by site, rather than sorting the information into separate sections. It also has header keys for the columns and is somewhat more human-readable to the new user. As shown in Fig.2, the beginnings of the first few lines demonstrate the similarity to the first few lines of the receiver block of the SINEX template. The loghist.txt file continues horizontally to present similar periods of validity for antenna and
A. W. Moore: A Review of Currently Available KS Network Summaries
592
IGSSite Logs SINEX template SINEX format definition Equipment naming table SINEX template errors loghisttxt logsum.txt igsnet archive WWW Tracking Network site list Global Data Center check_import files
Data Center Status files teqc software KS Analysis Report archive Links to IGS Analysis Centers
ftp://igscb.jpl.nasa.gov/pub/station/log/ ftp://igscb.jpl.nasa.gov/pub/station/general/igs.snx ftp:lligscb.jpl.nasa.gov/pub/data/format/sinex.txt t?p:lligscb.jpl.nasa.gov/pub/station/general/rcvr_ant.tab ftp://igscb.jpl.nasa.gov/pub/station/general/igs.snx.err ftp:l/igscb.jpl.nasa.gov/puWstation/general/loghist.txt ftp://igscb.jpl.nasa.gov/pub/station/general/logsum.txt ftp://igscb.jpl.nasa.govAnail/igsnet/ http://igscb.jpl.nasa.gov/network/list.html ftp://cddisa.gsfc.nasa.gov/pub/reports/gpsdata/check_import.cddisa ftp://igs.ensg ign.frlpuWigsldata/check_import.ign ftp:/Aox.ucsd.edu/pub/rinex/check_import.sio ftp:llcddisa.gsfc.nasa.gov/pub/reports/gpsstatus/ http://www.unavco ucar.edu/software/teqc/ http://igscb.jpl.nasa.gov/mail/igsreport/igsreport.html http://igscb.jpl.nasa.gov/organization/centers.html
Table 1. Locations of all referenced files on the Internet.
+SITE/RECEIVER albh A ---- P albh A ---- P albh A ---- P albh A ---- P albh A ---- P albh A ---- P
92:125:00000 92:128:85800 92:351:72300 93:113:57600 93:131:69180 93:298:79200
92:128:85800 92:351:72300 93:113:57600 93:131:69180 93:298:79200 93:327:70260
ROGUE ROGUE RCGUE ROGUE ROGUE ROGUE
+SITE/ANTENNA albh A ---albh A ---albh A ---albh A ----
92:125:00000 94:104:74100 95:011:80100 95:158:75120
94:104:74100 95:011:80100 95:158:75120 OO:OOO:OOOOO
AOAD/M_B AOAD/N_T AOAD/KT AOAD/M_T
P P P P
SNR-EC SNR-EC SNR-EC SNR-EC SNR-EC SNR-8100
312 312 312 312 312 119
Meenix Meenix Upgr Meenix 7.3 Meenix 7.3 Meenix 7.3 SFG2 0.0 L
91119 EmA 92172 EZRA 94368 EMRA 95174 EMRA
Fig. 1. Excerpts from the receiver and antenna sections of the SINEX template detail the time histories of equipment installed at IGS tracking stations.
Logfile Site Name Code DOMES # Latitude Longitude Elev Receiver Type Receiver Number --__---- __------__---_-_-_---- -_-- _---_---_ --_-_-__- __----_-- _-_- ---_-__------_-_--__ -_---_-_---~---~__-albh0003 Albert Head
ALBH 401291003 ALBH 401291003
48.3898 48.3898
236.5126 32.0 ROGUE SNR-EC 236.5126 32.0 ROGUE SNR-EC
312 312
Fii.2. Excerpt from the loghisttxt summary file showing an altemate presentation of receiver installation history.
Receiver Version _--__--__--__--__-__ Meenix Meenix Upgrade Ant Installed --~_---_------~_04-NAY-1992 25-MAY-1992
Ret Installed -__--___-__--__-04-MAY-1992 07-NAY-1992 23:50
Ant Removed _--___--_---_--_25-MAY-1992 14-APR-1994 20:35
Antenna Number Ret Removed Anthgt Antenna Type _--__--__--_--__- -_-_-_ _-___-_--__--__-___- __--__--__--_---_--_ 07-NAY-1992 23:50 0.129 AOAD/M_B ENRA 91119 16-DEC-1992 20:05 0.126 AOAD/KB ENRA 91119
Frequency Standard _-_---__-___--__-__CESIUN RUBIDIUM
Freq. Inst. ____-_____04-NAY-1992 ll-JUN-1993
Fig. 3. Examples of antenna and frequency standard information in the loghisttxt file.
Radome -------7-EMRA EMRA
593
A. W. Moore: A Review of Currently Available IGS Network .%mmaries
Receiver Type Antenna Type Latitude Longitude Anthgt Ref Code DOMES C Logfile Site Name -___---- _________________ -__- --__----- _------_- -_------- __-___ __--_ --_---~---~--~---~-- ______________T--_-albh0003 Albert Head algo Algonquin
ALBH 40129a003 ALGO 401041002
48.3898 45.9588
236.5126 -78.0714
0.100 ARP 0.100 BPA
AOA BENCHMARK ACT AOA SNR-12 ACT
AOAD/M_T AOAD/M_T
.
@HR.A
Fig. 4.logsum.txt swnman‘zes the current coniigurations of IGS sites.
frequency standard installations at the same site, as excerpted in Fig.3. 1.3
logsum.txt
This file provides the same information as loghist.txt, but only for the currently installed hardware rather than complete site histories, as shown in Fig.4. This summary file can be useful for quickly ascertaining which IGS sites currently have a certain equipment model installed.
2
Site performance
The igsnet report, originally developed by J. Zumberge at JPL, is emailed weekly to a large distribution and archived at the CB (see Table 1 for availability). This report attempts to summarize each site’s behavior rather than the station configuration as in the summaries of the previous section. The opening lines of this report for 2000-06-18, shown in Fig. 5, report on performance of a few International Terrestrial Reference Frame (ITRF) sites over the one-week period following this date. The Latency score is determined by the number of hours that a daily RINEX file took to reach the first Global Data Center, Quantity is determined by the average number of valid clock solutions, and the Quality score is formulated by whether a number of criteria are met (with equal weighting): valid clocks at least 250
The igsnet report condenses site performance into a simple, easy-to-read report. There have been occasions, however, where site changes which produced problematic raw data did not result in any decrease in the igsnet Quality scores. The CB is currently examining possible augmentations to the igsnet scoring algorithm with the intention of reliably diagnosing stations needing attention.
3
WWW CBIS station list
The Tracking Network station list, located on the CB Information System Web as given in Table 1, may be thought of as a sort of network summary. The excerpt shown in Fig.6 shows that it presents a complete list of the locations of currently installed sites, and indicates which stations are Global (analyzed by at least 3 IGS Analysis Centers, one of which is not on the same continent) based on recent IGS Analysis reports. Further, the clickable 4-character site id’s lead to the current site log, plots of the historic igsnet scores, and IGSMail messages relating to that site. Sites newer than 6 months in the IGS are also indicated for the benefit of users seeking the most recent additions to the network. 4
Non-CB summaries
IGS network summaries are also available outside the CB from Data Centers and Analysis Centers. This is not intended to be an exhaustive list but to highlight a representative few which have been particularly useful to the CB.
fewer than 100 phase bias resets 4.1
checkimport files
3D formal location error less than 1 cm rms pseudorange residuals less than 86 cm number of pseudorange measurements at least 0.9 x the number of phase measurements rms phase residuals less than 13 nm The criteria for these figures (except for Latency) are obtained from engineering data kindly provided by the JPL Analysis Center.
One summary file which is maintained at all 3 IGS Global Data Centers is the checkimport file. An excerpt of this report from one of the IGS’ Global Data Centers, the Crustal Dynamics Data Information System (CDDIS) at NASA’s Goddard Space Flight Center, is shown in Fig.7. This shows latency scores in days for the past days 186-188 of the year 2000 for the IGS sites listed across the top of the report, and illustrates how the check-import files give at-a-glance information on data holdings and typical latenaies for each site at each Global Data Center.
A. W. Moore: A Review of Currently Available IGS Network Summaries
594
IGS Stations 237 stations as of 31 Aug 2000. m Designates a Global Station. = Designates an site newer than 6 months to the IGS. View a list of inactive sites. Click on any I-character id for further information. id ' albh
City
Location
Victoria
Canada
. alp0 Algonquin Park alit Alice Springs mc2 Colorado Springs . [email protected] Ankara
Vlestlakc Key Biscayne. Miami Arewipa Arti Ascension Island Peninsula
Whangaparaoa AZlJSi3 lh*MM
Cibinong 8ridgetcv-n B*r Harbor Bilibino
1on
lat
(E)
(N)
ht
(m)
Agency
-123.4874 48.3898 32.0000 NRCanlGSC -78.0714 45.9588 202.0000 NRCan,GSD 133.8855 -23.6701 603.3580 AUSLIG -104.5246 38.8031 1911.0870 USNO/NOAA 35.8800 32.0300 1055.8300 RJGC 32.7586 39.8875 974.7680 IfAG -118.8303 34.1574 246.5566 NASA/JPL -80.1622 25.7347 0.0870 NOAA -71.4928 -16.4655 2488.9294 NASAlJPL 58.5605 56.4298 247.5110 RDAAC-IRIS -14.4120 -7.9512 105.1508 NASA/JPL 174.8344 -36.6028 132.0000 IGNS-JPL -117.9000 34.1300 144.7800 USGS 50.6081 26.2091 -17.0300 DMA 106.8489 -6.4911 158.1365 BAKO -59.6088 13.0878 -86.2782 NOAA -68.2217 44.3950 7.3680 NOAA 166.4380 68.0761 456.2380 RDAAC-IRIS
Canada
Australia U.S.A. Jordan Turkey USA USA Peru
Russian Federation Ascension Island New Zealand USA Bahrain Indonesia Barbados ".S.A Russian Federation
Fig. 6. The IGS station list available at the IGS CB web page. ***** CDDIS l *.**
AAAAAAAAAAAAABBBBBBBBBBBCCCCCCCCCCC LLLMMMNOORRSUAAAAIIJORRRAAEHIiHHIOOR BGICMUKAMETCCHKRRLSFRAMUSSDAUUWCCRO HOC2NNR1LQU1KROBIiIHSlZUSlAUTMRKlODl **t**t*t**t*t****** Last update : 7-JUL-00 21:00 (Day 189) **************** 00-188 1 1 1 1 . 111111111111.. 11.1111111111111 00-18711112 221112 .ll ..l..ll. 1'111111111111 00-18611113 2 .1111111111..11.1111111111111
Fig. 7. check-import Dly No. Site (Ii) Exp. ____ __- _____ albh 1 20948 algo 2 20910 alit 3 23013 amc2 1 10722
files at Data Centers provide availability and latency information for daily RINEX data files by site No. Obs.
___-_ 20774 20441 22957 10687
Pts. Avg. Avg. Pos. No. Del. % MPl MP2 Diff Slps V Receiver Type __-__ --_ _--- ____ __-- -__- - _-__-____-~_----~--0 99 0.27 0.21 0.03 3 1 AOA BENCHMARK ACT 0 97 0.24 0.25 0.03 2 1 AOA SNR-12 ACT 3 99 0.30 0.31 0.04 38 1 AOA ICS-40002 ACT 0 99 0.24 0.25 0.03 26 1 AOA SNR-12 ACT
Antenna Type ~_----~_---------_-AOAD/M_T EMRA AOAD/M_T AOAD/M_T
DOME
AOAD/M_T
Fig. 8. The “yyddd.status” files available from Data Centers provide simple quality checks on daily RINEX data files.
4.2
CDDIS yydddstatus files
Daily summary files at the CDDIS Data Center, named by the two-digit year (“yy”) and day of year (“ddd”), contain simple quality checks as provided by the teqc software (available and documented as shown in Table 1). A small portion of this file is provided in Fig.8. The quantities recorded in this file, such as multipath (“MP”) and cycle slips (“Sips”), have been useful in identifying some site problems, but like the igsnet Quality scores, they have not consistently been accurate predictors of problem data. 4.3
Analysis Reports
The complete set of IGS Analysis Reports is archived at the CB as shown in Table 1. These have a very readable summary included and will not be described in detail here. Many of the IGS Analysis Centers maintain network information based on their own analyses, available directly from the Centers (see Table 1 for links to Analysis Centers).
5
Conclusions
Many different IGS network summaries are available to meet various needs. The CB is always interested in improving or combining them to best serve the community without having a confusing assortment of summaries which largely duplicate one another. Input from analysts and the user community is valuable in identifying which summaries are most useful and where improvements can be made. The roles of me Data Centers and Analysis Centers in the summaries mentioned here are, as always, well appreciated by the Central Bureau.
Acknowledgements.
The research described in tbe paper was carried out at the Jet Propulsion Laboratory, California Jnstitute of Teclmology, under a contract with the National Aeronautics and Space Administration.
Pergamon
All rightsreserved 1464-1895/01/$ - see front matter
PII: S1464-1895(01)00106-5
A Review of
Currently
Available IGS Network Summaries
A. W. Moore
International GPS Service Central Bureau, Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 238-540, 4800 Oak Grove Dr., Pasadena CA 91109 USA Received 30 July 2000; accepted 18 Januav
2001
Abstract.
All components of the International GPS Serbite (IGS) community have cause to seek metrics, reports, or summaries of the IGS network. Station personnel may wish to monitor the performance of their own stations, users need to select subnetworks of stations appropriate to a particular study, and analysts must understand station configurations to assure high quality results. With its role in day-to-day management and coordination of the IGS, the Central Bureau devises and maintains information appropriate to these needs on its information system, and also refers users to useful summaries maintained at IGS Data Centers and Analysis Centers. This paper reviews the content and possible usage of several network summaries that are located at or useful to the Central Bureau, with the intent of ensuring that the community has ready access to information that enables both assessment and improvement of network performance. Q 2001 ElsevierScience Ltd. All rights reserved 1
Summaries based on site logs
The site logs on file at the IGS Central Bureau (CB) comprise the definitive source for IGS site information. As such, several network summaries are generated from the site logs. The locations for Internet access to the site logs and all other files referred to in this article are given in Table 1. 1.1
The SINEX template igs.snx
A file known as the SINEX (Solution INdependent Exchange format) template was developed by IGS Analysis Centers and the Central Bureau in 1997 with the purpose of standardizing the station metadata across Analysis Centers. The SINEX template is generated daily from the latest site logs at the CB. The SINEX format, which is also used for IGS station and coordinate velocity results, is fully documented at the Correspondence
to: Angelyn W. Moore
location detailed in Table 1; here a brief summary of the features of the SINEX template is presented. The template consists of several sections; in Fig.1, excerpts from the receiver and antenna sections are shown. The block beginning with “SITE/RECEIVER” shows receiver characteristics, starting alphabetically with station ALBH. Each line denotes the range of time by start and ending year, day and time of day that a particular receiver was installed at the site, identifying it by model, serial number, and firmware version. Similarly, the block beginning “SITE/ANTENNA” details the time history of of antenna and radome installations for the ALBH site, including number 95 174, which is active up to the current time as designated by convention with epoch oo:ooo:ooooo. It should be noted that the equipment naming conventions in the SIh%X template follow the accepted IGS codes as laid out in a naming table (see Table 1). Incoming site logs are checked for format compliance and are not accepted if the naming conventions are not followed; however, the SINEX template software continues to perform integrity checks and would post any error found to the SMEX template error file (igs.snx.err; see Table 1). Metadata inconsistencies between the SJ.NEXtemplate and RINEX (Receiver INdependent EXchange format) tracking data headers are also reported in this location, and station operators are automatically notified by email if any errors related to their sites are found. 1.2
loghist.txt
This file is quite similar to the SINEX template in that it is generated from current site logs and indicates a hardware history of IGS sites. The loghist.txt file, however, groups the metadata by site, rather than sorting the information into separate sections. It also has header keys for the columns and is somewhat more human-readable to the new user. As shown in Fig.2, the beginnings of the first few lines demonstrate the similarity to the first few lines of the receiver block of the SINEX template. The loghist.txt file continues horizontally to present similar periods of validity for antenna and
A. W. Moore: A Review of Currently Available KS Network Summaries
592
IGSSite Logs SINEX template SINEX format definition Equipment naming table SINEX template errors loghisttxt logsum.txt igsnet archive WWW Tracking Network site list Global Data Center check_import files
Data Center Status files teqc software KS Analysis Report archive Links to IGS Analysis Centers
ftp://igscb.jpl.nasa.gov/pub/station/log/ ftp://igscb.jpl.nasa.gov/pub/station/general/igs.snx ftp:lligscb.jpl.nasa.gov/pub/data/format/sinex.txt t?p:lligscb.jpl.nasa.gov/pub/station/general/rcvr_ant.tab ftp://igscb.jpl.nasa.gov/pub/station/general/igs.snx.err ftp:l/igscb.jpl.nasa.gov/puWstation/general/loghist.txt ftp://igscb.jpl.nasa.gov/pub/station/general/logsum.txt ftp://igscb.jpl.nasa.govAnail/igsnet/ http://igscb.jpl.nasa.gov/network/list.html ftp://cddisa.gsfc.nasa.gov/pub/reports/gpsdata/check_import.cddisa ftp://igs.ensg ign.frlpuWigsldata/check_import.ign ftp:/Aox.ucsd.edu/pub/rinex/check_import.sio ftp:llcddisa.gsfc.nasa.gov/pub/reports/gpsstatus/ http://www.unavco ucar.edu/software/teqc/ http://igscb.jpl.nasa.gov/mail/igsreport/igsreport.html http://igscb.jpl.nasa.gov/organization/centers.html
Table 1. Locations of all referenced files on the Internet.
+SITE/RECEIVER albh A ---- P albh A ---- P albh A ---- P albh A ---- P albh A ---- P albh A ---- P
92:125:00000 92:128:85800 92:351:72300 93:113:57600 93:131:69180 93:298:79200
92:128:85800 92:351:72300 93:113:57600 93:131:69180 93:298:79200 93:327:70260
ROGUE ROGUE RCGUE ROGUE ROGUE ROGUE
+SITE/ANTENNA albh A ---albh A ---albh A ---albh A ----
92:125:00000 94:104:74100 95:011:80100 95:158:75120
94:104:74100 95:011:80100 95:158:75120 OO:OOO:OOOOO
AOAD/M_B AOAD/N_T AOAD/KT AOAD/M_T
P P P P
SNR-EC SNR-EC SNR-EC SNR-EC SNR-EC SNR-8100
312 312 312 312 312 119
Meenix Meenix Upgr Meenix 7.3 Meenix 7.3 Meenix 7.3 SFG2 0.0 L
91119 EmA 92172 EZRA 94368 EMRA 95174 EMRA
Fig. 1. Excerpts from the receiver and antenna sections of the SINEX template detail the time histories of equipment installed at IGS tracking stations.
Logfile Site Name Code DOMES # Latitude Longitude Elev Receiver Type Receiver Number --__---- __------__---_-_-_---- -_-- _---_---_ --_-_-__- __----_-- _-_- ---_-__------_-_--__ -_---_-_---~---~__-albh0003 Albert Head
ALBH 401291003 ALBH 401291003
48.3898 48.3898
236.5126 32.0 ROGUE SNR-EC 236.5126 32.0 ROGUE SNR-EC
312 312
Fii.2. Excerpt from the loghisttxt summary file showing an altemate presentation of receiver installation history.
Receiver Version _--__--__--__--__-__ Meenix Meenix Upgrade Ant Installed --~_---_------~_04-NAY-1992 25-MAY-1992
Ret Installed -__--___-__--__-04-MAY-1992 07-NAY-1992 23:50
Ant Removed _--___--_---_--_25-MAY-1992 14-APR-1994 20:35
Antenna Number Ret Removed Anthgt Antenna Type _--__--__--_--__- -_-_-_ _-___-_--__--__-___- __--__--__--_---_--_ 07-NAY-1992 23:50 0.129 AOAD/M_B ENRA 91119 16-DEC-1992 20:05 0.126 AOAD/KB ENRA 91119
Frequency Standard _-_---__-___--__-__CESIUN RUBIDIUM
Freq. Inst. ____-_____04-NAY-1992 ll-JUN-1993
Fig. 3. Examples of antenna and frequency standard information in the loghisttxt file.
Radome -------7-EMRA EMRA
593
A. W. Moore: A Review of Currently Available IGS Network .%mmaries
Receiver Type Antenna Type Latitude Longitude Anthgt Ref Code DOMES C Logfile Site Name -___---- _________________ -__- --__----- _------_- -_------- __-___ __--_ --_---~---~--~---~-- ______________T--_-albh0003 Albert Head algo Algonquin
ALBH 40129a003 ALGO 401041002
48.3898 45.9588
236.5126 -78.0714
0.100 ARP 0.100 BPA
AOA BENCHMARK ACT AOA SNR-12 ACT
AOAD/M_T AOAD/M_T
.
@HR.A
Fig. 4.logsum.txt swnman‘zes the current coniigurations of IGS sites.
frequency standard installations at the same site, as excerpted in Fig.3. 1.3
logsum.txt
This file provides the same information as loghist.txt, but only for the currently installed hardware rather than complete site histories, as shown in Fig.4. This summary file can be useful for quickly ascertaining which IGS sites currently have a certain equipment model installed.
2
Site performance
The igsnet report, originally developed by J. Zumberge at JPL, is emailed weekly to a large distribution and archived at the CB (see Table 1 for availability). This report attempts to summarize each site’s behavior rather than the station configuration as in the summaries of the previous section. The opening lines of this report for 2000-06-18, shown in Fig. 5, report on performance of a few International Terrestrial Reference Frame (ITRF) sites over the one-week period following this date. The Latency score is determined by the number of hours that a daily RINEX file took to reach the first Global Data Center, Quantity is determined by the average number of valid clock solutions, and the Quality score is formulated by whether a number of criteria are met (with equal weighting): valid clocks at least 250
The igsnet report condenses site performance into a simple, easy-to-read report. There have been occasions, however, where site changes which produced problematic raw data did not result in any decrease in the igsnet Quality scores. The CB is currently examining possible augmentations to the igsnet scoring algorithm with the intention of reliably diagnosing stations needing attention.
3
WWW CBIS station list
The Tracking Network station list, located on the CB Information System Web as given in Table 1, may be thought of as a sort of network summary. The excerpt shown in Fig.6 shows that it presents a complete list of the locations of currently installed sites, and indicates which stations are Global (analyzed by at least 3 IGS Analysis Centers, one of which is not on the same continent) based on recent IGS Analysis reports. Further, the clickable 4-character site id’s lead to the current site log, plots of the historic igsnet scores, and IGSMail messages relating to that site. Sites newer than 6 months in the IGS are also indicated for the benefit of users seeking the most recent additions to the network. 4
Non-CB summaries
IGS network summaries are also available outside the CB from Data Centers and Analysis Centers. This is not intended to be an exhaustive list but to highlight a representative few which have been particularly useful to the CB.
fewer than 100 phase bias resets 4.1
checkimport files
3D formal location error less than 1 cm rms pseudorange residuals less than 86 cm number of pseudorange measurements at least 0.9 x the number of phase measurements rms phase residuals less than 13 nm The criteria for these figures (except for Latency) are obtained from engineering data kindly provided by the JPL Analysis Center.
One summary file which is maintained at all 3 IGS Global Data Centers is the checkimport file. An excerpt of this report from one of the IGS’ Global Data Centers, the Crustal Dynamics Data Information System (CDDIS) at NASA’s Goddard Space Flight Center, is shown in Fig.7. This shows latency scores in days for the past days 186-188 of the year 2000 for the IGS sites listed across the top of the report, and illustrates how the check-import files give at-a-glance information on data holdings and typical latenaies for each site at each Global Data Center.
A. W. Moore: A Review of Currently Available IGS Network Summaries
594
IGS Stations 237 stations as of 31 Aug 2000. m Designates a Global Station. = Designates an site newer than 6 months to the IGS. View a list of inactive sites. Click on any I-character id for further information. id ' albh
City
Location
Victoria
Canada
. alp0 Algonquin Park alit Alice Springs mc2 Colorado Springs . [email protected] Ankara
Vlestlakc Key Biscayne. Miami Arewipa Arti Ascension Island Peninsula
Whangaparaoa AZlJSi3 lh*MM
Cibinong 8ridgetcv-n B*r Harbor Bilibino
1on
lat
(E)
(N)
ht
(m)
Agency
-123.4874 48.3898 32.0000 NRCanlGSC -78.0714 45.9588 202.0000 NRCan,GSD 133.8855 -23.6701 603.3580 AUSLIG -104.5246 38.8031 1911.0870 USNO/NOAA 35.8800 32.0300 1055.8300 RJGC 32.7586 39.8875 974.7680 IfAG -118.8303 34.1574 246.5566 NASA/JPL -80.1622 25.7347 0.0870 NOAA -71.4928 -16.4655 2488.9294 NASAlJPL 58.5605 56.4298 247.5110 RDAAC-IRIS -14.4120 -7.9512 105.1508 NASA/JPL 174.8344 -36.6028 132.0000 IGNS-JPL -117.9000 34.1300 144.7800 USGS 50.6081 26.2091 -17.0300 DMA 106.8489 -6.4911 158.1365 BAKO -59.6088 13.0878 -86.2782 NOAA -68.2217 44.3950 7.3680 NOAA 166.4380 68.0761 456.2380 RDAAC-IRIS
Canada
Australia U.S.A. Jordan Turkey USA USA Peru
Russian Federation Ascension Island New Zealand USA Bahrain Indonesia Barbados ".S.A Russian Federation
Fig. 6. The IGS station list available at the IGS CB web page. ***** CDDIS l *.**
AAAAAAAAAAAAABBBBBBBBBBBCCCCCCCCCCC LLLMMMNOORRSUAAAAIIJORRRAAEHIiHHIOOR BGICMUKAMETCCHKRRLSFRAMUSSDAUUWCCRO HOC2NNR1LQU1KROBIiIHSlZUSlAUTMRKlODl **t**t*t**t*t****** Last update : 7-JUL-00 21:00 (Day 189) **************** 00-188 1 1 1 1 . 111111111111.. 11.1111111111111 00-18711112 221112 .ll ..l..ll. 1'111111111111 00-18611113 2 .1111111111..11.1111111111111
Fig. 7. check-import Dly No. Site (Ii) Exp. ____ __- _____ albh 1 20948 algo 2 20910 alit 3 23013 amc2 1 10722
files at Data Centers provide availability and latency information for daily RINEX data files by site No. Obs.
___-_ 20774 20441 22957 10687
Pts. Avg. Avg. Pos. No. Del. % MPl MP2 Diff Slps V Receiver Type __-__ --_ _--- ____ __-- -__- - _-__-____-~_----~--0 99 0.27 0.21 0.03 3 1 AOA BENCHMARK ACT 0 97 0.24 0.25 0.03 2 1 AOA SNR-12 ACT 3 99 0.30 0.31 0.04 38 1 AOA ICS-40002 ACT 0 99 0.24 0.25 0.03 26 1 AOA SNR-12 ACT
Antenna Type ~_----~_---------_-AOAD/M_T EMRA AOAD/M_T AOAD/M_T
DOME
AOAD/M_T
Fig. 8. The “yyddd.status” files available from Data Centers provide simple quality checks on daily RINEX data files.
4.2
CDDIS yydddstatus files
Daily summary files at the CDDIS Data Center, named by the two-digit year (“yy”) and day of year (“ddd”), contain simple quality checks as provided by the teqc software (available and documented as shown in Table 1). A small portion of this file is provided in Fig.8. The quantities recorded in this file, such as multipath (“MP”) and cycle slips (“Sips”), have been useful in identifying some site problems, but like the igsnet Quality scores, they have not consistently been accurate predictors of problem data. 4.3
Analysis Reports
The complete set of IGS Analysis Reports is archived at the CB as shown in Table 1. These have a very readable summary included and will not be described in detail here. Many of the IGS Analysis Centers maintain network information based on their own analyses, available directly from the Centers (see Table 1 for links to Analysis Centers).
5
Conclusions
Many different IGS network summaries are available to meet various needs. The CB is always interested in improving or combining them to best serve the community without having a confusing assortment of summaries which largely duplicate one another. Input from analysts and the user community is valuable in identifying which summaries are most useful and where improvements can be made. The roles of me Data Centers and Analysis Centers in the summaries mentioned here are, as always, well appreciated by the Central Bureau.
Acknowledgements.
The research described in tbe paper was carried out at the Jet Propulsion Laboratory, California Jnstitute of Teclmology, under a contract with the National Aeronautics and Space Administration.