Site offsets and data exclusions are given a code to represent a known or suspected origin. In the case of multiple configuration changes on the same date more than one code (up to 4) can be used, the offset may be explained by any of the codes.
IGS format site logs contain records that indicate either a change in receiver configuration or a change in antenna configuration. A new record in the log might indicate a change to a new receiver/antenna of the same type or a different type, either could cause an offset.
Since there is no seperate record in IGS format site logs for radome or antenna height changes they are recorded using a new antenna record. In the case of a new antenna record, if the antenna or radome name is not changed from the previous record (i.e. same make of equipment but new and hence a change) there is no way to know if a new antenna record relates to changes in antenna or radome configuration. Because of this ambiguity D and A often appear together.
Receiver, Antenna and Radome character codes follow the IGS conventions. Uncertainty in the origin of the offset may be expressed by appending a question mark to the string.
Current codes are:
-
A = Antenna change
C = Co-seismic - Nearby earthquake
D = Dome - Change of Radome
E = Error - Recording error in site log or email
F = Flange - Flange, Radio Frequency screening, Radio Frequency filtering or other Antenna modifications
H = Height change - Recorded change in Antenna height
M = Monument move - Offset used to connect adjacent sites
O = Oscillator - Change in external/internal receiver clock configuration
M = Monument move - Offset used to connect adjacent sites
P = Physical damage - Physical damage to site equipment, eg. lightning, vandalism etc.
R = Receiver change
S = Splitter - Antenna splitter used to connect more than one receiver to an antenna
U = Unknown
? = Uncertainty in assigned codes
Fields in the offset file
| Field | Chars | Format | Related Codes | Explanation |
| 0 | 1 | * or space | All | Commenting out field |
| 1 | 2-5 | 4-char site name | All | Name of site |
| 2 | 7-10 | 4-char site name | M | Name of additional site connected by estimating offset |
| 3 | 12-20 | Decimal year | All | Date of offset |
| 4 | 22-32 | yy:dayofyear:sec | All | Date of offset |
| 5 | 35-38 | 4 char GPS week | All | GPS week of offset |
| 6 | 40-43 | Up to 4-char code string | - | Explanatory offset code string |
| 7 | 45-47 | 3 char U or N or E | All | Visible appearance of offset in time series |
| 8 | 49-68 | 20 char Receiver code | R | Receiver operating before offset |
| 9 | 70-89 | 20 char Antenna code | A | Antenna in use before offset |
| 10 | 91-94 | 4 char Radome code | D | Radome in use before offset |
| 11 | 96-115 | 20 char Receiver code | R | Receiver operating after offset |
| 12 | 117-136 | 20 char Antenna code | A | Antenna in use after offset |
| 13 | 138-141 | 4 char Radome code | D | Radome in use after offset |
| 14 | 143-149 | 7 char height change | H | Difference in before and after antenna hgts |
| 15 | 151-153 | Char center code | ADEFHMOPRS |
Center used for related site information, analysis emails and site logs, e.g. igs |
| 16 | 155-158 | 4 char integer email number | ADEFHMOPRS | Analysis email number |
| 17 | 160-163 | 4 char log number yymm | ADEFHMOPRS |
Analysis site log name extension, e.g. igs0109.log. NOTE aus logs are mmyy |
| 18 | 165-167 | 3 char integer distance | C | Horizontal surface distance to earthquake epicenter in km |
| 19 | 169-171 | 3 char magnitude | C | Earthquake magnitude |
| 20 | 173- | Multi-char comment string | Any | Comments and additional info |
Fields in the exclusion file
| Field | Chars | Format | Related Codes | Explanation |
| 0 | 1 | * or space | All | Commenting out field |
| 1 | 2-5 | 4-char site name | All | Name of site |
| 2 | 7-15 | Decimal year | All | Start date of exclusion |
| 3 | 17-28 | yy:dayofyear:sec | All | Start date of exclusion |
| 4 | 30-33 | 4 char GPS week | All | Start GPS week of exclusion |
| 5 | 35-43 | Decimal year | All | End date of exclusion |
| 6 | 45-56 | yy:dayofyear:sec | All | End date of exclusion |
| 7 | 58-61 | 4 char GPS week | All | End GPS week of exclusion |
| 8 | 63-66 | Up to 4 char code string | - | Explanatory code string |
| 9 | 68-71 | 3 char U or N or E | All | Visible appearance in time series |
| 10 | 73-91 | 20 char Receiver code | R | Receiver operating during exclusiong period |
| 11 | 93-112 | 20 char Antenna code | A | Antenna in use during exclusion period |
| 12 | 114-117 | 4 char Radome code | D | Radome in use during exclusion period |
| 13 | 119-121 | 3 char center code | ADEFHMOPRS | Center for related site information, analysis emails |
| 14 | 123-126 | 4 char integer email number | ADEFHMOPRS | Analysis email number |
| 15 | 128-131 | 4 char log number yymm | ADEFHMOPRS |
Analysis site log name extension, e.g. igs0109.log. NOTE aus logs are mmyy. |
| 16 | 133 | Multi-char string | Any | Comments and additional info |
Web information
Site logs and site information can be accessed via the Internet. <stat> is the 4-char lowercase site id and <email#> is the 4 char integer email number.
IGS:
- IGS Central Bureau homepage
- IGS site logs (log names are <stat>YYMM.log, YYMM = date)
- IGS site info: http://igscb.jpl.nasa.gov/igscb/network/site/<stat>.html
- IGS emails
AUS:
- AUS homepage
- AUS site logs (log names are <stat>MMYY.log, MMYY = date)
- AUS site info: http://www.auslig.gov.au/geodesy/argn/<stat>.htm
- AUS emails: http://www.auslig.gov.au/geodesy/hypermail/argn-l/<email#>.html
EUR:
- Euref homepage
- Euref site logs (log names are <stat>YYMM.log, YYMM = date)
- Euref site info: http://www.epncb.oma.be/info/<stat>.html
- Euref emails: ftp://ftp.epncb.oma.be/pub/mail/eurefmail.<email#>
SIR:
Comments or questions about this page? Send mail to Lou Estey.
(lou
unavco.org)
Last modified Friday, 28-Jan-2011 21:10:25 UTC