The Effect of SCIGN Domes on the Vertical Antenna Phase Centre Position in Routine Processing of GPS Data
Bibliographic record
Abstract
The question of phase centre shifts for GPS antennas introduced by the addition of domes is receiving more attention as the number of continuous GPS sites multiply and the precision of solutions continue to improve. Our earliest experiences with clear acrylic domes used in the Western Canada Deformation Array (WCDA) had shown that changes in the vertical position of the phase centre exceeding 1.5 cm could be caused by the introduction of a dome. More recently, our deployments of SCIGN domes at WCDA sites showed no discernable shifts in the horizontal components but apparent shifts of over 2 cm in the estimates of height. Such large shifts have also been observed in practice by others but contradict calibration tests carried out by SCIGN and by NGS which indicate maximum vertical shifts of only a few millimetres due to the introduction of domes. Tests with the SCIGN short dome carried out at our GPS site at the Pacific Geoscience Centre (PGC5) demonstrate clearly that domes can introduce an elevation-dependent (1/cosZ) delay and consequently, the nominal mounting of SCIGN domes biases the tropospheric zenith delay resulting in an apparent shift in the L3 estimate of station height. Since estimates of the tropospheric delay are strongly dependent on the elevation cutoff used in the analysis as well as local site horizons, it is not possible to provide an absolute calibration correction for this effect. However, mounting the SCIGN dome so that its centre of curvature coincides with the mean position of the L1/L2 phase centres of the Dorne Margolin element significantly reduces this bias and effectively eliminates the large spurious change in height. This “dome effect” can be explained in terms of “lensing” of incident plane waves inside the dome.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.007 | 0.034 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".