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Site survey and co-location

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1 Site survey and co-location
Sten Bergstrand July 2017 SAFETY AND TRANSPORT MEASUREMENT SCIENCE AND TECHNOLOGY

2 Introduction Local ties are geometric vectors measured between reference points of different stations, including the full covariance information in both temporal and spatial domain Definitions are important to convey information Following Paris workshop Resolution between services available at IERS URL: rvey/Bergstrand_etal_REFAG2014_TieResolution.pdf (not REFAG proceedings…) Rotation of surveying results into ITRF via GNSS currently destroys any survey…

3 Every station has one geometric reference point
Stations have DOMES numbers Reference points are geometrically determined points on the stations The definitions of these points are determined by the services The term ”reference point” needs to be used exclusively for this geometrically determined point

4 One geometric reference point
Example of internet search result for ”gnss antenna reference point” – not recommended for clarity… Other relations, e.g. - PCO - PCV - pointing - internal geometries - time delays - systematic errors - deformation - etc… are part of the service obligation (with aid from surveyors, where applicable)

5 Every site should be represented by a physical marker.
Invariant to station changes Permanent Preferably attached to bedrock

6 Exemplified by DORIS antenna
Courtesy: Saunier et al.

7 VLBI Automatic schedule-generated terrestrial monitoring system developed, applied e.g. at CONT14 (Lösler et al.) GNSS antennas mounted on telescopes

8 How to incorporate local ties and uncertainties in next ITRF?
Plans, gateways, commitments, timings? Recommendations are already available since many years. Surveying techniques should generally perform better than current discrepancies between analytic site solutions Quality or quantity? Focus on any separate technique? More surveys? If so: who and how?

9 General Ishikawa diagram?
Reference point Ref. point to rec. unit Local network Geometry Deformation n points GNSS Temperature Geometry Accessibility Arcs Constraints Size Cables Rec.unit Definition Ground stability n measurements Elevation dependence Orientation of vertical Points Variation Frequency Observations Cut-offs Operator Play Repeatability Solar radiation Traceability Interval Temperature Pressure Temperature Length Longevity Stability Met.sensor height Monument Temporal evolution Instrument calibration

10 Thankyou – Please provide input!
Sten Bergstrand SAFETY AND TRANSPORT MEASUREMENT SCIENCE AND TECHNOLOGY


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