RF Compatibility tests of DORIS Simulator with VLBI Broadband Antenna at GGAO
Bibliographic record
Abstract
Radio Frequency Interference (RFI) characterization and mitigation at the Goddard Geophysical and Astronomical Observatory (GGAO) in Greenbelt Maryland USA is necessary to successfully co-locate the four geodetic techniques associated with the Space Geodesy Project. An issue of compatibility arises between the DORIS beacon and the VLBI Global Observing System (VGOS) radio telescope because both techniques possess mutual frequency coverage at 2036 MHz. At GGAO, the operational DORIS beacon is over 200 meters away from the VGOS system and behind buildings without a clear field of view. Because of its operational status, it is not possible to carry-out controlled experiments with this beacon. To circumvent this logistical problem, a DORIS test beacon and antenna was loaned to NASA for 2 months to test blocking schemes at a variety of distances to the VGOS radio telescope without disrupting DORIS operations. For the 2014 DORIS Workshop, an emphasis will be put on the testing conducted with a DORIS simulator at GGAO. An initial baseline test was run with an unblocked test beacon that was placed only 136 meters away. This beacon was only turned on with the VGOS radio telescope frontend protected by a cover plate. The power measured by a standard gain horn (SGH) placed near the intersection of rotational axes (IOA) measured power equal to -29.4 dBm at the test frequency of 2036245.78 KHz. We are investigating the implications of such a power level (-29.4 dBm) on the performance of the VGOS receiver. Mesh materials have been identified which are expected to be robust in all-weather conditions and effective in mitigating the reception of the DORIS signal by the VGOS technique (by ~15 dB). We will report on experiments conducted whereby both the DORIS Test beacon and the VGOS receiver are operated in a continuous mode to look at the effectiveness of the blocker. Because the blocking scheme is expected to introduce multi-path reflections, we will also report on these perturbations as detected by satellite-borne IDS receivers. Diagram of the configuration at GGAO
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".